Reception Help in NH

[jrgagne99]

Please help!

I am trying to pull in the 5 major stations (NBC, CBS, ABC, PBS, FOX) all transmitting from a distance of 70 miles, 342-deg, 2-edge. The stations are WPTZ, WCAX, WVNY, WETK, and WFFF. Here is my report:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3de2cb9bbcbb2eeb

Eventually, I would like to feed 3 TVs. Over the last 8 months or so, I have been experimenting with four antennas, all with fairly similar results in one key aspect, specifically, the inability to reliably receive WCAX. The antennas are (Denny's HD Stacker, CM-5020, HDB91X, and a homemade 8-foot K7MEM yagi designed for UHF ch-22).

In general, in 5-foot AGL tests with the TV very close to the antenna (4-feet of RG-6, no pre-amp) and the antenna pointed to 342-deg, I can get WPTZ fairly reliably, with spotty pick-up of WCAX. By "spotty", I mean if I move the antenna 5-feet to the right or left it can make the difference between 40% signal for WCAX and nothing. Oddly enough, in some locations I can receive WCAX at 5ft-AGL, but when I raise the antenna tripod up to 8ft-AGL, reception dies, until I move to the right or left about 6 feet. I have confirmed that this is a spatial anomaly somewhat repeatable from day to day, not a temporal one. Very strange behavior, but I figured it would go away when I permanently mounted the antenna on the roof at 30ft.

Not so. I moved the antenna to a gable-end mount at 30-ft AGL, with a CM-7778 pre-amp and 35-feet of RG-6 and an earth-ground-block for the coax-shield now part of the setup. I figured that WCAX should come in reliably, and I would have a decent shot at the rest of the channels on my list. Well, I am able to get WPTZ, WVNY (Hi-VHF, so only receives via HD Stacker and CM-5020), and WETK reliably, and even occasionally WFFF (especially with the HDB91X). But regardless of antenna, I cannot seem to get WCAX reliably, even though it has a relatively easy NM=8.2 dB, compared to the other UHF stations that I am receiving that are lower down on the list WETK (NM=-2.2) and WFFF (NM=-5.8).

WCAX is a priority for me since it is CBS affiliate and it carries the local NFL team. Why am I not receiving WCAX? I have a few ideas, such as (1) my down-lead comes in right underneath my electrical meter, and (2) a transformer is about 100-feet away from the antenna at about 325 degrees. Could either of these be causing interference? Any offending trees are at least 300 feet away, and about 50-feet tall. If this is a multi-path "null", would an antenna with a wider capture area (e.g. DB8e) improve reception of WCAX? I suppose I could try mounting the antenna somewhere else on the roof (either on the garage gable ends, or on the middle of the roof ridgeline using a tripod) but the wife thinks it is least-offensive on the gable end of the house, since it is "balanced" by the chimney on the other end of the house. I prefer not to mount it to the garage roof, since doing so would impede reception of some other lower-priority channels to the southeast.


Thanks in advance for any help you can offer!

[Nascarken]

Good day J99 I SEE that you have a high and low VHF TV ANTENNA and a ROTOR does the ROTOR STILL work if so I would keep the VHF ANTENNA THAT you have and add a ANTENNAS DETECT 91XG at the bottom of the VHF ANTENNA 3Ft apart from eachother with a channel master 7777amp and how long has the VHF ANTENNA Ben on the HOUSE

[jrgagne99]

Yes, the rotor still works. All four antennas I've been experimenting with are relatively new (<1 yr). As is the CM-7778. I have also tried a CM-7777 but that did not seem to make any difference.

For what it's worth, the signals of interest are located to the left in the whole-house photograph, so the trees at the right edge of that picture are not in my way. The intent of that picture was simply to show the current gable-end antenna location, the available roof-lines, and the telephone pole with the transformer at the top which is about 100-ft away. I have tried all four antennas at that roof-top location shown in that picture, with no real success on WCAX, yet decent signal on WETK and even WFFF, which have a noise margin over 8 dB down from WCAX.

[Nascarken]

So how high are you putting the antenna I suggest 10Ft off of the roofs line the higher the antennas the better they work and put the antennas A G L at 10 and see what happens

[rabbit73]

Welcome to the forum, JR:

Why am I not receiving WCAX?Interesting question. You should be receiving it, but you are not. I don't have an immediate solution, but I will give you my thoughts, for what they are worth.:)

WCAX IS listed on the tvfool report, but there is a shortage of people on the tvfool site to keep the data base current. It is listed as on the air at rabbitears.info:
http://www.rabbitears.info/market.php?request=station_search&callsign=wcax

but when I do a zip code search it isn't listed on rabbitears.info. However, the translator for WCAX, W20CS, IS listed, but it is too weak for your area:
http://www.rabbitears.info/search.php?request=zip_search&zipcode=03741&miles=60&address=&lat=&lon=&dbtype=dBm&height=

Wiki makes me think it is still on the air:
https://en.wikipedia.org/wiki/WCAX-TV

Why don't you call the station engineer; they might be having transmitter trouble.

more later when I have time

[jrgagne99]

Thanks for your reply Rabbit!

I'm pretty sure WCAX is still broadcasting, as I am able to receive "spotty" reception at ground level. I have even occasionally received it on my roof-top mount, but only marginal reception, and under the absolute best conditions, such as when early-morning fog fills in all the valleys between me and the tower located 70-miles away. In such cases, even WFFF (-6 dB NM) is coming in nice and strong. It is curious that it is one of the only signals on my TVfool report that does not have a birds-eye-view signal strength plot available for it.

I'm afraid that I am going to need to haul a TV up on the roof and check for hot spots in situ.

[rabbit73]

Is it possible you are receiving the WCAX translator, W20CS? It has the same virtual channel number. Do any of your TVs give the real channel number or frequency of a received channel in the menu?

http://forum.tvfool.com/attachment.php?attachmentid=2339&stc=1&d=1474412225

[rabbit73]

It is curious that it is one of the only signals on my TVfool report that does not have a birds-eye-view signal strength plot available for it.Yeah, I noticed that the coverage map was not available from the tvfool Interactive Map Browser. That made me wonder if it was really on the air. I did find a Longley-Rice coverage map on the FCC contour map:
http://www.rabbitears.info/contour.php?appid=2001335&map=Y&contour=Y&int=N&pop=N&incpop=&excpop=&z1=N&lprw=N&head=Y&asrn=&extras=&cir=&circen=44.525555555556%2C-72.816111111111

Red is weak, no color is weaker. You can see the coverage in your area is very spotty because of the rough terrain. A small change in location can make big difference in signal strength.

http://forum.tvfool.com/attachment.php?attachmentid=2340&stc=1&d=1474412942

[rabbit73]

I mean if I move the antenna 5-feet to the right or left it can make the difference between 40% signal for WCAX and nothing. Oddly enough, in some locations I can receive WCAX at 5ft-AGL, but when I raise the antenna tripod up to 8ft-AGL, reception dies, until I move to the right or left about 6 feet. I have confirmed that this is a spatial anomaly somewhat repeatable from day to day, not a temporal one. Very strange behavior, but I figured it would go away when I permanently mounted the antenna on the roof at 30ft.I have noticed the same thing at my location. The wave front presented to the antenna has a non-uniform field.

I was having trouble receiving CH 42 because my antenna was facing the wrong direction. I went across the street and setup a 2-bay UHF antenna, my meter, and a preamp. I was able to get a nice scan and a stronger signal with the antenna aimed at the transmitter for CH42.

Interestingly, when I moved the antenna a few feet left or right, without changing the height or azimuth, there was a big difference in the signal strength and scan quality. This is most likely because of the tree line in front of the antenna about 200 ft away which created the non-uniform field.

http://forum.tvfool.com/attachment.php?attachmentid=1599&d=1442620525

I understand the need to mount the antenna in a location that "looks nice," but the antenna must be mounted where the signal is strongest, which is often not where you want it. Antenna installers call it walking-the-roof, signal level meter and test antenna in hand, to find a hot spot.

There are several possible things going on with the height. When the antenna is close to the ground, it can receive a reflection of the signal from the ground which is added to the direct signal in phase; called "ground bounce." When you raised the antenna, you lost the reinforcement from the reflection and your antenna was then behind the electrostatic field that surrounds the power line from the pole to the house.

If this is a multi-path "null", would an antenna with a wider capture area (e.g. DB8e) improve reception of WCAX?Maybe not.
http://www.hdtvprimer.com/antennas/siting.html

scroll down to Non-uniform fields

[Nascarken]

Now that's cool LOL

[jrgagne99]

Is it possible you are receiving the WCAX translator, W20CS? It has the same virtual channel number. Do any of your TVs give the real channel number or frequency of a received channel in the menu?



I'm pretty sure it is not W20CS. With my TV in "manual" mode, when I type in "22" it automagically goes to 3.1. If I type in "20", it stays put and says "no signal". Unfortunately, the other TV is the same type, only smaller, and all the menus are exactly the same. They are circa-2008 Sylvanias.

[jrgagne99]

I understand the need to mount the antenna in a location that "looks nice," but the antenna must be mounted where the signal is strongest, which is often not where you want it. Antenna installers call it walking-the-roof, signal level meter and test antenna in hand, to find a hot spot.

I ordered a 7" handheld TV for fun, and will use it to try to "walk the roof" to find a hot spot when it arrives.



When you raised the antenna, you lost the reinforcement from the reflection and your antenna was then behind the electrostatic field that surrounds the power line from the pole to the house.

Tomorrow, I will try to post a picture of what the antenna "sees", to see if the you think the power line occlusion/obfuscation may be at play.

[jrgagne99]

Maybe not.
http://www.hdtvprimer.com/antennas/siting.html

scroll down to Non-uniform fields


Very Interesting! In all of my research, I had not seen that particular webpage. I will study this.

If I do "walk the roof" and happen to find a hot spot for WCAX, do you think the hot spot will stay in the same place from day-to-day, and over the seasons and years?

[Nascarken]

Good question will it rabbit 73

[rabbit73]

This is the terrain profile for WCAX from tvfool:
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3de2cb9bbcbb2eeb%26t%3dALLTV%26n%3d7

This is the profile using different software:

http://forum.tvfool.com/attachment.php?attachmentid=2341&stc=1&d=1474416565

http://forum.tvfool.com/attachment.php?attachmentid=2342&stc=1&d=1474416999

The WCAX signal passes over two ridges, which causes scattering, resulting a non-uniform field as you saw on the hdtvprimer page. Point A is further out; point B is just before your antenna. I can see the ridge at point C behind your house. Using "what if" height changes on the interactive map browser:
At 115 ft 1Edge NM 17.6 dB; the signal clears point B
At 485 ft LOS NM 41.0 dB; the signal clears point A

What bothers me is, if the terrain affects WCAX, then why doesn't it affect WPTZ?

I suggest you hunt for a good location for WCAX (somewhere on you property even if it means a mast behind the house) using the HDB91X with the front of the antenna tilted up (15 deg ?) to catch the signal coming down from the ridge. You need to get the antenna as high as you can because there is a lot of ground clutter on the hill just in front of the antenna.

[Nascarken]

Yes that's where the higth and A G L comes into play is that right

[jrgagne99]

Red is weak, no color is weaker. You can see the coverage in your area is very spotty because of the rough terrain. A small change in location can make big difference in signal strength.



My house is actually situated right on the boundary between Orange and No Color. But the my ground tests were typically in the yard or driveway, which are in "Orange". That, coupled with the ground bounce, probably explains my spotty ground reception, yet poor roof-top reception.

[rabbit73]

If I do "walk the roof" and happen to find a hot spot for WCAX, do you think the hot spot will stay in the same place from day-to-day, and over the seasons and years?The hot spot stayed stable for me. My wife wanted a battery operated TV for use during a power failure. The only place it would work indoors with analog TV was by a window.

http://i496.photobucket.com/albums/rr328/rabbit73_photos/BatteryTV_zpshazyfqkd.jpg (http://s496.photobucket.com/user/rabbit73_photos/media/BatteryTV_zpshazyfqkd.jpg.html)

When digital TV came along, an indoor antenna would not work because there was an aluminum foil vapor barrier on the insulation in the outer walls; we were living in a Faraday Cage.

The landlord said I could mount an antenna outside if it did not show from the street. I selected a hot spot inside the decorator blocks on the porch. The landlady said she wanted me to move it to the left where it wasn't as obvious. I explained to her that the antenna needed to be where the signals were the strongest, and I would build an attractive enclosure for the antenna. She said OK.

http://forum.tvfool.com/attachment.php?attachmentid=2343&stc=1&d=1474419910

http://forum.tvfool.com/attachment.php?attachmentid=2344&stc=1&d=1474419910

The 4-bay UHF antenna is about 5 ft off the ground. I added a folded dipole for VHF channel 13. The signals come through the holes in the blocks without much attenuation. The VHF signals are attenuated a little more because the size of the holes is frequency related. In other words, the holes act like a high pass filter.:)

http://forum.tvfool.com/attachment.php?attachmentid=2345&stc=1&d=1474421218

[Tigerbangs]

All of the Burlington-Plattsburgh stations broadcast from almost exactly the same spot on Mt. Mansfield, so the issues that you are having with WCAX are most likely an issue of signal bounce because of the specific frequency of WCAX and the mountains between the transmitters and you.

Rabbit beat me to the punch when he suggested changing the tilt of the HDX-91. I have experienced going from a no-signal to a solid signal just by tilting the front of the antenna up, sometimes by more than 15 degrees. So, before you undo all of your handiwork on the roof, try the tilt first.

By the way, WFFF (FOX) has a pretty tight transmitting pattern that puts little signal out your way, so, if you see WFFF with the tilt, you ought to see WCAX without too much of an issue.

Another thought might be to horizontally stack 2 HBX-91s, which would increase the likelihood of finding additional stray signal from WCAX. HBX-91s are cheap enough to be worth giving it a try. Mount them on a fiberglass horizontal pole approx. 39"apart. Be sure that your coax cable leadin is exactly the same length from each antenna, and combine them using a high-quality coax splitter-joiner. The front end elevation tilt recommendation is still valid.

[Nascarken]

Ha tiger what is a H D X ?

[jrgagne99]

The WCAX signal passes over two ridges, which causes scattering, resulting a non-uniform field as you saw on the hdtvprimer page. Point A is further out; point B is just before your antenna.

http://forum.tvfool.com/attachment.php?attachmentid=2341&stc=1&d=1474416565


Actually, it looks like the signal might be diffracted by three ridges (3-edge diffraction?) on its way to my house. The first one is at 37 miles from the transmitter, then #2 at 55 miles, then #3 at 68 miles. I think my house is actually at point "B" in your zoomed in plot. So the last diffraction ridge is located about 2.5 miles away. This is consistent with my observations of the surrounding terrain. In an case, I will try to aim the antenna upward for a few days before (or maybe in parallel with) hunting around for other hot spots.

[rabbit73]

Actually, it looks like the signal might be diffracted by three ridges (3-edge diffraction?) on its way to my house.TVFOOL uses the term 2Edge for 2 or more.

I think my house is actually at point "B" in your zoomed in plot.I don't agree:

http://forum.tvfool.com/attachment.php?attachmentid=2346&stc=1&d=1474464195

I will not post the coordinates for your antenna without your permission.

Try it for yourself here:
http://www.heywhatsthat.com/profiler.html

enter transmitter coordinates and click on Find:
http://forum.tvfool.com/attachment.php?attachmentid=2347&stc=1&d=1474467002

click on 3983 ft and add transmitter antenna height AGL of +151 feet in pop up window and click OK. Height AGL is found here:
http://www.rabbitears.info/tvq.php?request=items&facid=46728

http://forum.tvfool.com/attachment.php?attachmentid=2348&stc=1&d=1474467653

enter your coordinates, click Find, and add your antenna height

http://forum.tvfool.com/attachment.php?attachmentid=2349&stc=1&d=1474469959

[jrgagne99]

Most respectfully, I think the topographic data in this case is flawed or there is at least a difference of interpretation. Having walked through those woods to the north-west of my house, the ground is all very flat, with maybe a five-to-ten foot change in elevation at most through there. The tree-tops however are about 50-feet tall, and I think that is what the google-earth data are showing at point "B".

In fact, the Google 3D-view shows evidence of this. There is a small clearing in the middle of the woods 1/4 mile away along the signal-path that shows as a depression in Google-3D. That is definitely not the case.

See the attached picture:

[rabbit73]

What you say is certainly possible. Elevation used to be measured on the ground using bench marks. It is now often done by aerial survey which probably includes tree height. In any event, the ground clutter is messing with the signal.

[jrgagne99]

In any event, the ground clutter is messing with the signal.

Agreed.

I will try aiming the antenna up a bit, walking the roof, and then possibly stacking antennas.

[jrgagne99]

The Longley-Rice plots from www.rabbitears.info indicate about a 100-foot shift in the reception morphology for WCAX, relative to WPTZ. The shift puts my house right on the edge of a WCAX deadzone. I'm guessing this is a frequency effect, (473 MHz vs. 521 MHz) since the general reception pattern in the vicinity of my house is quite similar between each signal.

[ADTech]

The Longley-Rice plots from www.rabbitears.info indicate about a 100-foot shift in the reception morphology for WCAX, relative to WPTZ. The shift puts my house right on the edge of a WCAX deadzone.

You're assuming precision in the underlying input data that does not exist. The rabbitears.info calculations uses a much coarser elevation data set than does TVFool's input data, consequently, comparing the two results is not a heads-up comparison. It's somewhat akin to making a comparison in the video quality between a 1280P input source vs a VGA-resolution source on a UHD display and expecting 4K results.


I'm guessing this is a frequency effect, (473 MHz vs. 521 MHz) since the general reception pattern in the vicinity of my house is quite similar between each signal.Absolutely.

[rabbit73]

You're assuming precision in the underlying input data that does not exist.Correct

The computer simulations for the tvfool report, the Longley-Rice coverage map, and the terrain profile, give the impression of accuracy that exceeds reality. Look how I was fooled by the elevation profile.

I don't expect anything better than a location specified to an accuracy of a football field length or two.
The Longley-Rice plots from www.rabbitears.info indicate about a 100-foot shift in the reception morphology for WCAX, relative to WPTZ. The shift puts my house right on the edge of a WCAX deadzone.Nicely done comparison, but the tuner makes the final decision.

Your tuner will take all factors into consideration that affect signal strength and signal quality (as defined by SNR and uncorrected errors), and tell you if the signal is good enough.

When I aim an antenna, I go for max signal strength, then readjust for max signal quality. They are not always at the same azimuth because of multipath reflections.

[jrgagne99]

Your tuner will take all factors into consideration that affect signal strength and signal quality (as defined by SNR and uncorrected errors), and tell you if the signal is good enough.


I agree completely- the TV receiver is the ultimate arbiter.

That being said, can you guys recommend a TV brand or maybe even a particular model that has additional signal quality measurements other than just signal-strength? Both of my current TV's only have a signal strength meter. Since I'd like to get a third TV for the basement anyway, I might as well get one that has additional signal diagnostics (SNR, uncorrected errors, etc.) to assist in my current effort. Generally, those kind of capabilities seem hard to find on TV spec-sheets; and blue-shirts generally don't know much about the OTA capabilities of the TVs they sell.

Also, is there a particular brand or model that is thought to have higher-quality OTA receivers than competitors?

[rabbit73]

I have been very happy with my Sony KDL22L5000 and KDL32R400A.

KDL22L5000
Bad signal with picture freeze, SNR below 15 dB, and uncorrected errors:

http://forum.tvfool.com/attachment.php?attachmentid=1386&d=1438807158

Good Signal

http://forum.tvfool.com/attachment.php?attachmentid=1387&d=1438807179

KDL22L5000 calibration chart

http://i496.photobucket.com/albums/rr328/rabbit73_photos/SONYSSVSdBmVchart2_zpsmz94qqxv.jpg (http://s496.photobucket.com/user/rabbit73_photos/media/SONYSSVSdBmVchart2_zpsmz94qqxv.jpg.html)

My KDL32R400A has an even greater range of readings; the screen is similar. Here is its calibration chart:

http://i496.photobucket.com/albums/rr328/rabbit73_photos/SSCHART%20KDL32R400A_1_zpstasl68zu.jpg (http://s496.photobucket.com/user/rabbit73_photos/media/SSCHART%20KDL32R400A_1_zpstasl68zu.jpg.html)

So, when I bought the 32R400A, I was getting a TV and a signal level meter for the price of a TV.

KDL32R400A screen with TV connected to cable; readings are similar to OTA readings:

http://i496.photobucket.com/albums/rr328/rabbit73_photos/KDL32R400ADS_1_zpsqjqurwtl.jpg (http://s496.photobucket.com/user/rabbit73_photos/media/KDL32R400ADS_1_zpsqjqurwtl.jpg.html)

One of thee days I'll connect an antenna to the 32R400A and do another screen shot.

You will want to make sure the model you choose has a Diagnostics Screen. For my 32R400A:
Menu > Settings > Setup > Product Support > Signal Diagnostics

I think the smallest model now is 40". They do make a few 32", but most are Multi-System which doesn't have a tuner for ATSC.

[jrgagne99]

HBX-91s are cheap enough to be worth giving it a try.... combine them using a high-quality coax splitter-joiner.

HDB91X are now on sale for $39.99, so I think I'll give this a try.

Which splitter/joiner should I select? I only seem to find ones with 3.5 dB insertion loss. Wouldn't that result in a net loss?

[Nascarken]

Don't FOR GET THE amp channel master 78/7777,or the newest one by channel master

[ADTech]

Which splitter/joiner should I select? I only seem to find ones with 3.5 dB insertion loss. Wouldn't that result in a net loss? That's as good as it gets for using a splitter as a combiner.

However, when used as a combiner and everything is phased properly, that combiner loss disappears as if by magic (it's actually math**) leaving only the loss caused by power dissipation and inefficiency, typically somewhere from 0.4 up to a dB or so. Using a 1/2 dB as a planning factor is usually good enough.

** See http://www.hdtvprimer.com/ANTENNAS/ganging.html for a tutorial.

[jrgagne99]

Does anybody have experience with ballasted antenna mounts? I found an old Dish Network ballasted roofmount for free on the side of the road. I'm wondering I could use it to mount my 2x HDB91X's + a VHF, as opposed to buying a tripod that screws into the roof. The roof is about a 3/12 pitch and the ballast mount has room for 8 cinder blocks. Obviously, the wind loads are my main concern. My house is situated in a relatively windy area, especially in winter.

[ADTech]

I've used non-penetrating mounts several times. Usually a couple of cinder blocks or sand bags is all it takes but it's going to depend a lot on the footprint of your "found" mount, the mast length involved, the relative wind load of the antenna, and your roof's particulars (slope, composition, etc).

[jrgagne99]

Antennas: two HDB91X's + Stellar Labs 30-2476 VHF
Mast height is 6-feet
3/12 pitch,
Asphault shingles
Mount base area= 36"x36" (Holds 8 cinder blocks 33 lbs each = 264 lbs)


My gut check says that 264 lbs is a lot, so that this ought to work...

[WIRELESS ENGINEER]

You may need more capture area on UHF and no yagi design will give you that and their gain tends to be on higher channels which you don't need
An 8 bay bowtie design may give you what you seek
And the channel master hd4228 is the best UHF antenna on the market as a direct result of massive capture area
If the 4228 won't pick it up then nothing will

[jrgagne99]

The 4228 is probably the next thing I'll try if the 2x HDB91X's don't work, plus with walking the roof to hopefully find a better spot.

[jrgagne99]

I tried combining two HDB91Xs together, and the performance did not really improve, infact, it gets a little worse. Questions on this:

1) How close to "exactly the same length" do the feed lines need to be. I'm using two 3-foot lenghts, and they vary by about 1/4". Is this too much?

2) Will it be worth fiddling with the separation? I tried 39" as a first cut, per Tigerbangs suggestion.

3) I'm guessing the antennas also need to be "perfectly parallel". Its kind of hard to ensure this exactly unless I add another cross-piece. Seems like this might be worthwhile. Thoughts?

Thanks guys!

[jrgagne99]

Bump .

[jrgagne99]

Lately I've been trying to pull in WFFF (Fox affiliate), which has a NM=-5.8 dB on my Tvfool report (borderline "extreme measures required"). I'm well aware of the difficulties of pulling in a 2+ edge signal 70.5 miles away. Well, this past Saturday in preparation for the Super Bowl, I vertically stacked two SolidSignal HDB8x's, walked the roof to find a "hot-spot", and finally had success!, sort of... I was able to receive WFFF all night Saturday, into the afternoon on Sunday, and then by 2pm, the signal was gone. Bummer, no Superbowl from the comfort of my own living room...

Anyway, I have two questions about this situation:

1) Given that reception lasted for 20+ hours could this have been a "tropospheric" reception phenomenon? I haven't re-established reception since it went out, but it's because the wind blew the antenna out of position on Sunday night and then it snowed later, so I haven't been able to climb up on the roof to re-aim it and secure things better. I am sure that it was not a change in aim that caused LOS on Sunday afternoon.

2) The combined capture area of my two stacked HDB8x's 1728 sq-in. This is exactly the same area as a single DB8e. Do you guys think a single DB8e will perform as well (or maybe even better) than my stacked HDB8X setup?

Thanks in advance, as always.

[rabbit73]

The signal path for WFFF is very similar to the WCAX signal path, but WFFF is running much less power and its antenna is a little lower on a separate tower.

http://forum.tvfool.com/attachment.php?attachmentid=2554&stc=1&d=1486689565

http://forum.tvfool.com/attachment.php?attachmentid=2553&stc=1&d=1486689565

You are on the extreme fringe of coverage for WFFF

http://forum.tvfool.com/attachment.php?attachmentid=2555&stc=1&d=1486692691

A closeup of WFFF coverage; purple is very weak, no color is dead zone

http://forum.tvfool.com/attachment.php?attachmentid=2556&stc=1&d=1486692691

1) Given that reception lasted for 20+ hours could this have been a "tropospheric" reception phenomenon?Yes, very possible. You can track changes in tropospheric events here:
http://www.dxinfocentre.com/tropo.html

Other local changes in atmospheric conditions can also affect reception of WFFF.

I vertically stacked two SolidSignal HDB8x's,An 8-bay antenna has a horizontal beamwidth that is more narrow than a 4-bay, but its vertical beamwidth is the same as the 4-bay.

When you have a vertical stack of two 8-bays, the vertical beamwidth is even more narrow than one 8-bay. This means the azimuth aim AND the elevation aim are very critical. It might be necessary to tilt the top of the antenna back to aim slightly above horizontal for peak signal.

One of my antenna test locations has a clear path across water, but I found it necessary to tilt my 4-bay for max signal.

http://forum.tvfool.com/attachment.php?attachmentid=2413&d=1477409166

[jrgagne99]

Thanks very much Rabbit for the dxinfo URL.

How about 2xHDB8x vs. 1xDB8e? Thinking in terms of the capture area. I ordered a DB8e on sale, with VHF dipole (maybe it'll pick up WVNY) for $160, free shipping.

[rabbit73]

Two 8-bay antennas will have a larger capture area, but that doesn't guarantee signal increase, as I mentioned in post #9. The larger capture area theory assumes that the wave front is uniform across the whole antenna; that is rarely true especially with weak 2Edge signals that have been scattered by terrain interference.

The DB8e has been optimized for the latest 14-51 band. I have no idea about the actual gain of the HDB8X based on range tests.

http://forum.tvfool.com/attachment.php?attachmentid=2045&d=1466633825

http://forum.tvfool.com/attachment.php?attachmentid=1746&d=1446858514

In this case, a smaller capture gives a stronger signal:

http://forum.tvfool.com/attachment.php?attachmentid=2370&stc=1&d=1475692853

[jrgagne99]

In my latest experiment, I combined a Stellar Labs 30-2476 VHF yagi with a DB8e 8-bay using a UVSJ combiner (Stellar labs 33-2230 UVSJ). Real channel 25 (WNNE) is strong enough that it is separately received by both antennas, even though I point them 90-degrees off from the Real-25 tower to pick up Burlington stations. I confirmed this by separately removing UHF and VHF feeds to the UVSJ, and I receive Real-25 in both cases. Strangely, when both feeds to the UVSJ are populated, the UVSJ does not allow Real-25 to pass through to the output.

Any thoughts on what might be going on here? Is this some form of destructive interference where some very low amplitude CH-25 signal passes through the VHF-pass filter and destructively interferes with the CH-25 coming through the UHF-pass section?

Is this an example of UVSJ's "not always doing what they're supposed to" and why I've seen several people on this forum recommend using separate coax runs and an A/B switch for UHF and VHF instead of using a UVSJ combiner?

[ADTech]

The UVSJ you used is an unknown quantity. I've not made nor have I ever seen a detailed analysis of its performance.

[jrgagne99]

Which UVSJ one would you recommend ADTech?

[JoeAZ]

In my latest experiment, I combined a Stellar Labs 30-2476 VHF yagi with a DB8e 8-bay using a UVSJ combiner (Stellar labs 33-2230 UVSJ). Real channel 25 (WNNE) is strong enough that it is separately received by both antennas, even though I point them 90-degrees off from the Real-25 tower to pick up Burlington stations. I confirmed this by separately removing UHF and VHF feeds to the UVSJ, and I receive Real-25 in both cases. Strangely, when both feeds to the UVSJ are populated, the UVSJ does not allow Real-25 to pass through to the output.

Any thoughts on what might be going on here? Is this some form of destructive interference where some very low amplitude CH-25 signal passes through the VHF-pass filter and destructively interferes with the CH-25 coming through the UHF-pass section?

Is this an example of UVSJ's "not always doing what they're supposed to" and why I've seen several people on this forum recommend using separate coax runs and an A/B switch for UHF and VHF instead of using a UVSJ combiner?

Thank You for so eloquently describing what I have experienced in
the field so many, many times.... In theory, a good UVSJ should
work under all conditions but in practice, that is not so. That is why
I always recommend keeping separate coax runs and using an A/B
switch.....

[ADTech]

Which UVSJ one would you recommend ADTech?Given the limited availability since so many ones from the past are NLA, ours is the only one currently on the market that I have current performance data on. I tested a number of them 5-6 years ago but haven't revisited them since most of them have been discontinued.

Thank You for so eloquently describing what I have experienced in
the field so many, many times.... In theory, a good UVSJ should
work under all conditions but in practice, that is not so. That is why
I always recommend keeping separate coax runs and using an A/B
switch.....

Remember to old TV commercial that said "If it doesn't say Sunkist, you don't know what you're getting""? (https://www.youtube.com/watch?v=5jP09HFiRD0) When importers like MCM bring is stuff from China without any performance data provided, there's no telling what you're buying.

:shrug:

Strangely, when both feeds to the UVSJ are populated, the UVSJ does not allow Real-25 to pass through to the output. Sounds more like there's simply excessive insertion loss in the UHF high pass filter and the signal was simply lost due to an inefficient device.
Is this some form of destructive interference where some very low amplitude CH-25 signal passes through the VHF-pass filter and destructively interferes with the CH-25 coming through the UHF-pass section?Unlikely, see previous.

I don't recall, but are you using a preamp with this arrangement. Have you tried amplifying only the UHF signals? IIRC, your combiner has a switch that allows pass-through on the UHF-only port and, if implemented, that would overcome insertion loss of the combiner's UHF port.

[rabbit73]

In my latest experiment, I combined a Stellar Labs 30-2476 VHF yagi with a DB8e 8-bay using a UVSJ combiner (Stellar labs 33-2230 UVSJ). Real channel 25 (WNNE) is strong enough that it is separately received by both antennas, even though I point them 90-degrees off from the Real-25 tower to pick up Burlington stations. I confirmed this by separately removing UHF and VHF feeds to the UVSJ, and I receive Real-25 in both cases. Strangely, when both feeds to the UVSJ are populated, the UVSJ does not allow Real-25 to pass through to the output.You are expecting too much and not giving even the best UVSJ a chance. When you aim your DB8e at Burlington, you are placing WNNE perfectly in the antenna null, making it much weaker. That is what you would do if you wanted to reject WNNE, not receive it.

http://forum.tvfool.com/attachment.php?attachmentid=2727&stc=1&d=1497985402

As ADTech said, their UVSJ is the only one currently available with known performance.

http://forum.tvfool.com/attachment.php?attachmentid=2728&stc=1&d=1497986210

http://forum.tvfool.com/attachment.php?attachmentid=2735&stc=1&d=1497990764

There are a few Radio Shack 15-2586 UVSJs still left; the last one I measured did well.

http://forum.tvfool.com/attachment.php?attachmentid=2730&stc=1&d=1497987107

http://forum.tvfool.com/attachment.php?attachmentid=2731&stc=1&d=1497987107

I opened up the MCM 33-2230 and wasn't impressed, but haven't measured it yet. They are using an all purpose board modified for use as a UVSJ, with a lot of empty pads for components.

http://forum.tvfool.com/attachment.php?attachmentid=2732&stc=1&d=1497987508

http://forum.tvfool.com/attachment.php?attachmentid=2733&stc=1&d=1497987508

http://forum.tvfool.com/attachment.php?attachmentid=2734&stc=1&d=1497987508

[rabbit73]

Any thoughts on what might be going on here? Is this some form of destructive interference where some very low amplitude CH-25 signal passes through the VHF-pass filter and destructively interferes with the CH-25 coming through the UHF-pass section?I think it is possible. You have a very weak CH-25 signal coming from BOTH antennas.
Is this an example of UVSJ's "not always doing what they're supposed to" ?It's an example of trying to make a UVSJ do what it was never designed to do.
and why I've seen several people on this forum recommend using separate coax runs and an A/B switch for UHF and VHF instead of using a UVSJ combiner?That can work well if the antennas are aimed at the transmitters.

If you want reliable reception of WNNE, the antenna must be aimed at WNNE.

[JoeAZ]

Ad Tech and Rabbit,

The current ambient outdoor temperature at 5,600 feet
is almost 100f. In the lower deserts, the ambient temperature
is over 120f. Now, take a small, enclosed case, filled with
rather delicate electronics...... See how long they hold up.....
I've seen melted circuit boards, melted plastics, and melted
and burned electronic components. Know matter how good
the quality, heat is the enemy of electronics. That is why
auto manufacturers have moved the most expensive and most
delicate electronics inside the car, usually under a seat, where
the heat impact is lessened......

[rabbit73]

A car alternator is designed to run with a case temperature of 200°F, according to a GM tech in Detroit that I consulted. He had done many measurements on car and truck alternators using thermocouples attached with thermal epoxy. I measured car alternators with a Fluke thermocouple probe when I was installing transmitters in cars to find out how much extra current could be drawn by the transmitter without damaging the alternator. For every 10 degrees C rise in temperature above 212°F (100°C), the life of the alternator is cut in half. The insulation on the wires starts to soften at about 120°C, depending upon the insulation Class. The diodes get pretty hot, too.

And your point is, for the current topic?

[JoeAZ]

A car alternator is designed to run with a case temperature of 200°F, according to a GM tech in Detroit that I consulted. He had done many measurements on car and truck alternators using thermocouples attached with thermal epoxy. I measured car alternators with a Fluke thermocouple probe when I was installing transmitters in cars to find out how much extra current could be drawn by the transmitter without damaging the alternator. For every 10 degrees C rise in temperature above 212°F (100°C), the life of the alternator is cut in half. The insulation on the wires starts to soften at about 120°C, depending upon the insulation Class. The diodes get pretty hot, too.

And your point is, for the current topic?

"Now, take a small, enclosed case, filled with
rather delicate electronics...... See how long they hold up.....
I've seen melted circuit boards, melted plastics, and melted
and burned electronic components. Know matter how good
the quality, heat is the enemy of electronics."

My point is that electrical components like USVJ's, are the
most likely to fail and the most problematic......

And when would you possibly see a 200f under hood temperature
in a modern car???? None I know of.... and certainly not when
the ambient temperature is above 120f.... That is why we
see so many car fires these days...........

[rabbit73]

200f under hood temperatureRead it again, Joe; I said alternator case (the metal housing of the alternator) temperature, not ambient temperature under the hood.
My point is that electrical components like USVJ's, are the
most likely to fail and the most problematic......Your point that electrical components will fail above a certain temperature is valid, but UVSJs can tolerate higher temperatures than a preamp out in the sun because they do not have any active components, just wire inductors and ceramic capacitors.

I consider the UVSJ one of the most reliable components in an antenna system.

It is so rare for a UVSJ to fail that I have never heard of it, but many preamps do fail.

I can imagine any antenna system component can fail from a lightning strike, but they are not expected to survive a strike.

Even coax will fail outside when it gets old or corroded from water entry.

Just exactly how, in detail, do you think the OP should set up his system using an A/B switch; which antennas aimed where, to get what he wants?

What happens when the viewer at TV #1 wants the switch set to "A", but the viewer at TV #2 wants the switch set to "B"?

A system with an A/B switch IS very reliable (until the switch fails), but if the TV tuners are not able to add a channel after scan, then it is necessary to rescan after switching to the other antenna. User convenience is just as important as reliability.

[jrgagne99]

I did some more tests this evening, (all in the last 30 minutes before sunset, for what it's worth). It seems that the 33-2230 UVSJ is greatly attenuating my UHF signals. I was using my Solid Signal HDB91X UHF yagi mounted at 30 feet AGL, with a CM-7778 pre-amp at the mast. In Configuration#1, I sent the HDB91X signal directly to the pre-amp (no UVSJ). In Configuration #2, I combined the HDB91X with the StellarLabs 30-2476 VHF yagi using the UVSJ, and then fed that to the pre-amp. Here are the SNRs as reported by my Sony Bravia (typically need SNR>14 to receive channel):

Real Ch____Config#1 (no UVSJ)___Config#2 (with UVSJ + VHF yagi)
13___________0 (no VHF ant)________18
14___________20__________________15
22___________19__________________6
24___________24__________________9
25___________21__________________8
32___________18__________________10
50___________29__________________17


I repeated configuration #1 a second time and confirmed this wasn't a temporal effect. I also did configuration #2 again, but left the VHF input to the UVSJ empty. The results were the same as with the 30-2476 VHF yagi feeding the UVSJ (except of course no Real 13 reception). Leaving the UVSJ out of the picture (HDB91X and pre-amp only) and signal strengths seem to be unchanged as i write this, even though it is now over 1 hour after sunset. One thing I didn't try was to see how Real13 is affected by the UVSJ. It comes in with the UVSJ (SNR=18), but I didn't measure the signal strength if I use the VHF yagi directly, with no UVSJ. Maybe it would be a fair bit higher. Also, FWIW, there is about 100 feet of RG-6 between my mast mounted pre-amp and the power inserter.

It would seem that I should try a different brand of UVSJ. I would rather like to avoid two lines and an A/B switch.

[rabbit73]

Thanks for the test results.
It seems that the 33-2230 UVSJ is greatly attenuating my UHF signals.It looks that way to me, too.

has weatherproof housing

https://www.antennasdirect.com/store/UHF-VHF-Antenna-Combiners.html

no housing

https://www.radioshack.com/products/radioshack-vhf-uhf-gold-plated-splitter-combiner

maybe try both?

[jrgagne99]

What about the RCA TVPRAMP1Z Preamp, instead of a new UVSJ?

www.amazon.com/RCA-TVPRAMP1Z-Preamplifier-... (www.amazon.com/RCA-TVPRAMP1Z-Preamplifier-Outdoor-Antenna/dp/B003P92D9Y/ref=pd_sbs_23_1?_encoding=UTF8&pd_rd_i=B003P92D9Y&pd_rd_r=EVN005QQMWYMXS4107KF&pd_rd_w=o5R5s&pd_rd_wg=b56th&psc=1&refRID=EVN005QQMWYMXS4107KF)

This preamp serves dual purpose, replacing the UVSJ and my CM-7778 pre-amp.

Generally speaking, are folks having good experiences with these?

[rabbit73]

The RCA TVPRAMP1R does have dual inputs and is inexpensive. It seems to do well; I'm using one with a GE 34792 Attic Indoor antenna.

There are reports about QC problems, in particular about the combined/separate switch not making good contact with the VHF antenna with the switch in the separate position. The fix is to set the switch to combined and use a UVSJ, which brings you back to where you started.

There is also a review by an installer (Robert Hughes) on Amazon who likes the RCA preamp, and has bought many of them as Amazon Warehouse Deals. The power inserters have a high DOA rate, probably because they were returns that were never tested.

I'm seeing a similar pattern with Duracell batteries on Amazon. Amazon is shipping them in plain packaging instead of the original packaging; many batteries are old, DOA, or leaking.

I suggest you try the RCA preamp, but order from Walmart instead of Amazon.

I'm still confident about the AD and RS UVSJs, but not the MCM. Maybe I'll make some tests of the MCM to see how it compares with your results.

[ADTech]

If you buy the RCA preamp, buy two of them and keep your receipts.... Just saying.

[jrgagne99]

Thanks for the feedback. I just bought both the RCA combiner/preamp from Walmart and the Antennas Direct UVSJ from Amazon. I will test both setups and keep you posted on my results.

[jrgagne99]

What's the consensus on a dedicated deep fringe VHF-Hi antenna?

My Stellar Labs 30-2476 yagi works for WVNY, but DW thinks it is too big. What are the odds a Clearstream 5 VHF rig would work? $139 each is kind of steep to gamble on....

[ADTech]

The simulation's math suggests it will work. However, my practical experience with the predicted vs actual signal levels suggests that the calculations for 2-edge paths is often highly variable. I've had instances where Fool indicated a +10 dB margin and no signals were in the air above the noise floor and others where Fool predicted -20 dB margin and reception was 24/7 reliable. At 70 miles away and with less than 10 kW ERP, I'm surprised their signal is even making the trip to your location.

If you try it out, but it from someplace that offers an easy return policy and then watch your return dates. Amazon, for example, only offers 30 days and, if you're a Prime member, quick shipping and pre-paid returns (usually). If you order directly from us, we offer 90 days to return, slow-boat "free" shipping, and you pay the postage if it gets sent back. Other retailers will have something somewhere in the middle.

[rabbit73]

It seems that the 33-2230 UVSJ is greatly attenuating my UHF signals.

It would seem that I should try a different brand of UVSJ. I would rather like to avoid two lines and an A/B switch.That got me curious, so I made some measurements to compare four UVSJs:

MCM 33-2230
Radio Shack 15-2586
Antennas Direct EU385CF-1S
Macom (Old)

For the first measurements, I used a Blonder Tongue HAVM-1UA Frequency Agile Modulator as a stable signal source, and a Sadelco DisplayMax 800 Signal Level Meter. The modulator puts out an analog signal; I used the video carrier for each channel. The Sadelco meter has 0.1 dB resolution.

http://forum.tvfool.com/attachment.php?attachmentid=2759&d=1498349912

I was having a problem getting consistent measurements. The Sadelco meter has a built-in calibration reference and at certain intervals will correct its readings. This was difficult for me to deal with when making 0.1 dB resolution measurements, so I switched to my Sadelco 719E meter that has a panel meter with wide 1 dB divisions in the center of the scale that allows me to interpolate to the nearest 0.1 dB.

The Sadelco 719E is on the left; the DisplayMax 800 on the right:

http://forum.tvfool.com/attachment.php?attachmentid=1481&d=1440873529

I used the red divisions and the second scale -10 to +20 dBmV.

http://forum.tvfool.com/attachment.php?attachmentid=2757&d=1498343132

I would read that as +2.8 dBmV.

To make a measurement, I first connected the modulator to the meter with an F-81 adapter and took a reading. I then substituted the UVSJ, UHF and common ports, for the adapter for the second reading.

There was an attenuator at the output of the modulator and at the input of the meter to try to keep the line "flat" (low SWR).

UHF Insertion Loss of Four UVSJs

CH MCM 33-2230 RS 15-2586 AD EU385CF-1S Macom (Old)

F-81 UVSJ Loss F-81 UVSJ Loss F-81 UVSJ Loss F-81 UVSJ Loss
---dBmV-- -dB- ---dBmV-- -dB- ---dBmV-- -dB- ---dBmV-- -dB-

15 7.1 5.8 1.3 7.1 6.5 0.6 7.1 6.8 0.3 7.1 7.0 0.1

28 6.1 5.4 0.7 6.1 5.5 0.6 6.2 5.8 0.4 6.2 6.1 0.1

45 5.3 4.3 1.0 5.3 5.0 0.3 5.3 4.9 0.4 5.3 5.2 0.1


The MCM 33-2230 does have a higher insertion loss that might make a difference if your marginal signals are at the "Digital Cliff."

The Macom UVSJ has very low loss because it has fewer components.

http://forum.tvfool.com/attachment.php?attachmentid=2762&stc=1&d=1498430206

http://forum.tvfool.com/attachment.php?attachmentid=2763&stc=1&d=1498430206

L1, C1, and L2 are the lowpass VHF filter; C2, L4, C3, and L3 are the UHF highpass filter.

This UVSJ will pass power to a preamp for the VHF antenna through L1 and L2.

[jrgagne99]

Thanks for the UVSJ test-info Rabbit.

While I was waiting for the RCA TVPRAMP1Z and Antennas Direct mast-mount UVSJ to arrive, I tried another UVSJ that I remembered I had purchased a while back on Amazon- a Blonder-Tongue ZHLSJ. It showed the same wacky UHF attenuation that the MCM 33-2230 did. I was now suspicious that something else in my setup was at play. However, when I plugged in the Antennas Direct UVSJ, it worked swimmingly. No UHF or VHF attenuation! Additionally, the RCA TVPRAMP1Z, with its separate UHF and VHF inputs, worked great as well! Maybe MCM is using Blonder-Tongue components in their parts (or vice-versa) I don't know, but in any case, they both appeared to be defective.

Anyway, for two days now, I've been pulling in WCAX, WPTZ, and WVNY at SNRs all greater than 20 dB, with only very rare pixellations, and no drop-outs. I'm even getting WETK, which is way down at NM=-2.2dB on my report. I'm using the HDB91X for UHF and the MCM 30-2476 for VHF-Hi.

My stretch-goal now is to pull in WFFF (Real Ch 43, NM=-5.8 dB). I have occasionally achieved this before using two vertically stacked HDB8X's positioned in a certain spot on my roof. But that configuration is a real wind-sail, and we live in a especially windy spot. So I'm thinking of stacking two HDB91Xs instead.

Question: What separation distance should I try (to start with) for vertical or horizontal stacking of two HDB91X antennas?

[rickbb]

If you buy the RCA preamp, buy two of them and keep your receipts.... Just saying.

Ditto that. I've had 4 of them, 3 actually worked.

[rabbit73]

While I was waiting for the RCA TVPRAMP1Z and Antennas Direct mast-mount UVSJ to arrive, I tried another UVSJ that I remembered I had purchased a while back on Amazon- a Blonder-Tongue ZHLSJ. It showed the same wacky UHF attenuation that the MCM 33-2230 did. I was now suspicious that something else in my setup was at play. However, when I plugged in the Antennas Direct UVSJ, it worked swimmingly. No UHF or VHF attenuation! Additionally, the RCA TVPRAMP1Z, with its separate UHF and VHF inputs, worked great as well! Maybe MCM is using Blonder-Tongue components in their parts (or vice-versa) I don't know, but in any case, they both appeared to be defective.A HLSJ is not the same as a UVSJ. A UVSJ passes UHF and blocks VHF-High and VHF-Low on the high port; it passes VHF-High and VHF-Low on the low port. A HLSJ passes VHF-Low and blocks VHF-High and UHF on the low port; it passes VHF-High and UHF on the high port.

http://forum.tvfool.com/attachment.php?attachmentid=2642&stc=1&d=1494006989

http://forum.tvfool.com/attachment.php?attachmentid=2297&d=1473349481

http://forum.tvfool.com/attachment.php?attachmentid=2769&stc=1&d=1498678126

IOW, the crossover for a UVSJ is between VHF-High and UHF; the crossover for a HLSJ is between VHF-Low and VHF-High.

Glad to hear that the AD UVSJ is working well for you.
Question: What separation distance should I try (to start with) for vertical or horizontal stacking of two HDB91X antennas?

http://forum.tvfool.com/attachment.php?attachmentid=2770&stc=1&d=1498682526

[ADTech]

Even though an HLSJ is a different device than what was needed, it should have no ill effect on UHF pass-through provided the ports were not reversed. Only high-VHF should have been affected (assuming correct connection and no other defects).

[jrgagne99]

Thanks for the info on spacing Rabbit. The chart is slightly confusing, but if I'm reading it right, it looks like the optimum vertical spacing is 0.67*lambda, and the optimum horizontal spacing is 1*lambda, where lambda is the wavelength of the "lower-channel antenna". Since my UHF antennas are obviously both the same, I guess I'll take that to mean the the lowest frequency in the UHF band (Ch14 = 473 MHz), so my lambda is 25-inches. The spacing to optimize reception of WFFF (Real Ch43 = 647 MHz) should be based on lambda=18".

At least those are some ball-park numbers to start with. I'll try vertical stacking first because it is easier to implement. I notice that 0.67*lambda for Ch14 is 16.5". That seems pretty close, but we'll see if it works. The recommended vertical spacing is even closer for Ch43 (0.67*lambda = 12.25").

[rabbit73]

That seems pretty close,It seems too close to me also.

This is how seeyabarney stacked his antennas:

http://forum.tvfool.com/attachment.php?attachmentid=2773&d=1498789361

his thread:

http://forum.tvfool.com/showthread.php?t=16301

[jrgagne99]

Due to the height of the corner reflectors on the HDB91X, the closest I could space them was about 25". It made maybe a 1 dB improvement in SNR on some channels. Others were unchanged. WFFF might have gone up by 1 dB. Without more sophisticated measurement equipment it is difficult to quantify, especially because in deep-fringe, the SNRs bounce around by 1-2 dB constantly. Even looking at the high-water mark over 30-second intervals, that measurement itself can change by 2-3 dB over a 10-minute period. So it can be difficult to tease out whether the effect is mechanical or temporal.
Multiple repeat measurements at different times of the day are needed to have a better chance at understanding the true impact.

To join the signals, I'm using coax cables of the same length (within 1/4 inch or so), and a combiner scavenged from my HDB8X 8-bay. I'm worried that the combiner losses might be swamping any stacking gains. Can anyone recommend a ultra-low loss combiner I should try?

[rabbit73]

I'm worried that the combiner losses might be swamping any stacking gains. Can anyone recommend a ultra-low loss combiner I should try?Most combiners are a splitter used in reverse as a combiner. The insertion loss is very low, average about 0.5 dB. So, the most you can gain by stacking is about 2.5 dB.

However, if the field is non-uniform and one antenna receives a weaker signal, then the gain from stacking can be much less. It's a difficult concept to grasp, but it is possible to end up with less gain from two stacked antennas than what you had with one, even if both antennas are identical, are aimed at the same azimuth, and have feedlines that are the same length.
http://www.hdtvprimer.com/ANTENNAS/merging.html

WFFF will be moving to channel 16, so you will want your antenna to have the highest gain at the low end of UHF, like the DB8E.
http://www.rabbitears.info/market.php?request=station_search&callsign=wfff

Can anyone recommend a ultra-low loss combiner I should try?The only way I know of to combine with a lower loss is to connect both lines together in parallel, giving an impedance of 37.5 ohms, and add a 1/4 wave matching section of 50 ohm coax which transforms the 37.5 ohms to 75 ohms. It would be a custom job. This is what Calaveras did with his two 91XG antennas.
http://www.aa6g.org/DTV/index.html

http://www.aa6g.org/DTV/ABD/Antenna_Block_Diagram.html

http://forum.tvfool.com/attachment.php?attachmentid=2778&stc=1&d=1498854750

[jrgagne99]

Thank-you as always for the info Rabbit. I had no idea that broadcasters were switching channels again. This time it is part of the 2016-2017 FCC incentive auction (per Wikipedia). I called the junior station engineer up on the mountain-top and he said there will be some new transmitter equipment installed as part of the switch. He didn't know if it would be more powerful or less powerful, but I'm going to call the senior engineer Monday night who junior told me will surely know. He's been up there since Elvis died in 1977. :) Hopefully, power levels will go up and coverage will increase...

All other things being equal (i.e. transmitter power), does a move down the band (i.e. WFFF going from Ch43 to Ch16) bode well for deep-fringe reception areas like my house?

[rabbit73]

All other things being equal (i.e. transmitter power), does a move down the band (i.e. WFFF going from Ch43 to Ch16) bode well for deep-fringe reception areas like my house?I would say yes, if the antenna for Ch16 has at least as much gain as the antenna used for Ch43. I base this on the fact that VHF signals are more frequently used in mountainous areas because they can make it over terrain obstructions more easily. This would seem to apply to UHF low end vs UHF high end signals as well, to a lesser extent.

To summarize, these are the factors to consider when hunting for weak marginal signals:

1. Select an antenna that has the highest gain available for your most desired channel. In your case, it would probably be the AD DB8E after the move to Ch16:

http://forum.tvfool.com/attachment.php?attachmentid=2590&stc=1&d=1489973660

2. Mount the antenna in the best hot spot you can find on your property. That might not be where you want it for the sake of appearance. Often, a single antenna up higher will out perform a stacked pair and will be easier to mount.
3. Keep the coax between the antenna and the preamp input short; every 16 feet of coax is like a 1 dB loss of antenna gain for UHF.
4. Consider switching to a low Noise Figure preamp like the KT-200. They can make the reception of weak signals easier, but are more sensitive to static damage; that's the trade-off.


http://forum.tvfool.com/attachment.php?attachmentid=1859&d=1453496093

This is the way it works:

The antenna gain must make the signal strong enough to exceed the Noise Figure of the preamp plus the 15 dB minimum required SNR for the signal. Once the signal reaches that point, the preamp will amplify the signal to overcome the distribution losses. The preamp will also amplify the Thermal Noise Floor which will bury the tuner Noise Figure, making it irrelevant.

The metric for the antenna system performance is called the System Noise Figure; the lower the number, the better. It is primarily determined by the preamp at the beginning of the chain. The System Noise Figure can be calculated using the Friis Noise formula.
https://en.wikipedia.org/wiki/Friis_formulas_for_noise
An important consequence of this formula is that the overall noise figure of a radio receiver is primarily established by the noise figure of its first amplifying stage. Subsequent stages have a diminishing effect on signal-to-noise ratio. For this reason, the first stage amplifier in a receiver is often called the low-noise amplifier (LNA).

System Noise Figure calculations for the above Noise Margin diagram:

http://forum.tvfool.com/attachment.php?attachmentid=2552&d=1486498735

reducing the balun loss and the preamp NF:

http://forum.tvfool.com/attachment.php?attachmentid=2591&stc=1&d=1489975414

[jrgagne99]

Thanks Rabbit. I had it in the back of my mind that the pre-amp Noise Figure NF is yet another component for me to optimize. Data on the common ones is sometimes hard to find. Here is an effort to condense NF values from commonly (and less-commonly) available pre-amps all into one spot.

CM-7777/7778:
"typically less than 2 dB"
https://www.channelmaster.com/TV_Antenna_Preamplifier_p/cm-7777.htm

Winegard LNA-200 "Boost XT"
"1 dB typical"
http://www.winegard.com/amplifiers
but probably overstated according to multiple users

Antennas Direct Juice
"1.5dB on VHF, < 3dB on UHF"
AVS forum post:
http://www.avsforum.com/forum/25-hdtv-technical/1913001-antennas-direct-new-clearstream-juice-preamp.html

RCA TVPRAMP1R:
Low VHF - 3.9 dB
High VHF - 3.1 dB NF
UHF - 2.6 dB NF
(from Pete Higgins post, quoting ADTech on this tvfool forum:
https://forum.tvfool.com/showthread.php?t=13530)

KT-200
0.4 dB
http://www.kitztech.com/KT200.html

Research Communications Pre-amps
0.4 dB
configurable for different combinations of VHF-lo, VHF hi, UHF
http://www.researchcomms.com/hdtv.html


It looks to me like the KT-200 might be worth a try for my situation, especially since Research Comms is in the UK. Do you guys have experience with the KT-200s? Is the 0.4 dB NF legit?

[rabbit73]

It looks to me like the KT-200 might be worth a try for my situation, especially since Research Comms is in the UK. Do you guys have experience with the KT-200s? Is the 0.4 dB NF legit?The NF is optimistic, but still quite good. That would be the one I would try. Get the coax powered outdoor enclosure version. I can't guarantee that it will improve your reception, but I think it's worth a try.
http://www.kitztech.com/KT200.html

http://www.kitztech.com/standard_coax.html

The LNA-200 isn't as good as when first released. They made some design changes to meet a price point that reduced the performance. Also the shielding isn't adequate. It uses 5V which isn't so good with long coax runs because of the voltage drop. CM made the same mistake with the CM7777hd Amplify preamp.
http://www.highdefforum.com/local-hdtv-info-reception/148959-channelmaster-7777hd.html

Calaveras on AVS tested a whole bunch. His results in the attachment.

[jrgagne99]

My current setup:

Recently I've been using a single HDB91X at 30 feet agl and a MCM-30-2476 at 28.5 feet agl. Both aimed at 342 degrees, combined with the RCA-TVPRAMP1R preamp/diplexer at the mast, then 100 feet of RG-6 then 50 feet of RG-59. I get good reception of all the 342-degree stations except WFFF which is too far down in the weeds for me i guess.

Observations:

1) My wife didn't like the look of the 4-element planar reflector on the 30-2476, so I modified it down to a single element reflector. After making the change, I lost about 3 dB of SNR on WVNY (real-13), as reported by my Sony Bravia. I was not surprised by this. The SNR is still reliably at 22+, so it is a non-issue (minimum of 14 dB required for reception). So i thought.

2) I installed a generic splitter to try reception on 2 TVs last night. With the secondary TV off, signal strength on the main TV#1 (the Sony) was unchanged across all channels, compared to my original no-splitter setup. But when I turned on TV#2, the signal strength reported by the Sony for WVNY dropped by another 3 dB. The effect was very repeatable, and no other station showed a change in signal strength on TV#1. Last night was no big deal, but on stormy nights, this could cause a reception problem for WVNY, as I will be approaching the 14 dB minimum.

Any thoughts as to what might be causing this? Would a distribution amplifier help in this case?

Thanks!

[JoeAZ]

One red flag would be the excessively long cable runs.
Another red flag would be mixing RG6 and RG59 in
the same system. Cannot help but wonder if there could
be an impedence mismatch?

[ADTech]

...mixing RG6 and RG59 in the same system. Cannot help but wonder if there could be an impedence mismatch? Both are 75 ohm impedance. No mismatch there.

Of greater concern is that the RG59 typically has a thinner diameter center conductor. If you connect it to a female F-connector that has previously had RG6 connected to it, you may find that the connector does not make a secure physical and electrical connection. Such a loose connection behaves like a capacitor and can cause a loss of lower frequency (think VHF frequencies) pass-through.

[rickbb]

2) I installed a generic splitter to try reception on 2 TVs last night. With the secondary TV off, signal strength on the main TV#1 (the Sony) was unchanged across all channels, compared to my original no-splitter setup. But when I turned on TV#2, the signal strength reported by the Sony for WVNY dropped by another 3 dB. The effect was very repeatable, and no other station showed a change in signal strength on TV#1. Last night was no big deal, but on stormy nights, this could cause a reception problem for WVNY, as I will be approaching the 14 dB minimum.

Any thoughts as to what might be causing this? Would a distribution amplifier help in this case?

Thanks!

I'm guessing here, but it sounds like the 2nd TV is not terminating the signal when off, sending the current backup the cable to the splitter, which oddly is sending it to the 1st TV. This is the only thing I can think of to allow this turning of the 3db drop on and off like that.

If you try adding another amp, get an adjustable model so you can dial it up and down to find the sweet spot between good signal and overload.

Wineguard makes a model that I've used just in front of a 2 way splitter for a similar situation. I can't remember the model off hand and I'm out of town for the week or I'd look at it. I added it after a long run to 2 TV's close together. The rest of the house did not need an amp so the adjustable one just served these 2 "remote" TVs.

[rabbit73]

1) My wife didn't like the look of the 4-element planar reflector on the 30-2476, so I modified it down to a single element reflector.

Your wife dictates what the antenna should look like?

I thought the signal should dictate what the antenna looks like.

Yes, the coax between the preamp (near the antenna, I hope) and the power inserter should be one piece (except for the break for the grounding block) of high quality RG6 with a solid copper center conductor. I bought four different 100 FT lengths of coax and tested them for voltage drop:

http://www.highdefforum.com/1410658-post20.html

The 100ft Solid Signal Custom RG6 Quad with solid copper center conductor was the best.
http://www.solidsignal.com/pview.asp?p=sscblq

I then tested the coax for voltage drop and signal strength with increasing length, starting with worst 3 of 4:
http://www.highdefforum.com/1410662-post23.html

and:
http://www.highdefforum.com/1411096-post27.html

I didn't user the best SS Quad because I was trying to simulate a worst case for that OP, but it would have been the best.
The SNR is still reliably at 22+, so it is a non-issue (minimum of 14 dB required for reception).I would consider 15 or 16 dB as a minimum.
2) I installed a generic splitter to try reception on 2 TVs last night. With the secondary TV off, signal strength on the main TV#1 (the Sony) was unchanged across all channels, compared to my original no-splitter setup. But when I turned on TV#2, the signal strength reported by the Sony for WVNY dropped by another 3 dB.Exactly what generic splitter did you use?
Would a distribution amplifier help in this case?Maybe; try improving the coax first. Then try another splitter. Then, replace the passive splitter with a CM 3412 or 3414.

If you connect it to a female F-connector that has previously had RG6 connected to it, you may find that the connector does not make a secure physical and electrical connection. Such a loose connection behaves like a capacitor and can cause a loss of lower frequency (think VHF frequencies) pass-through.I noticed that problem with cable systems. The low channels would be weak, the higher UHF channels would be OK. The center conductor wasn't making good contact. The gap, as ADTech said, formed a capacitor that the UHF signals were better able to jump than the VHF signals (it's called capacative reactance, and is frequency dependent). It can also be caused by poor shield contact.

If you had that problem between the preamp and the power inserter, the preamp wouldn't get proper voltage, but it could happen after the power inserter.

I test F-81 adapters and other female connectors with a short length of bare copper wire to be sure it grabs the center conductor securely. Actually, I use a piece of copper clad steel center conductor from a short length of RG6 because it is more rigid, and file it to a point for easy insertion. I have found that some cheap F-81 adapters are really bad.

http://forum.tvfool.com/attachment.php?attachmentid=2816&stc=1&d=1501113484

http://forum.tvfool.com/attachment.php?attachmentid=2817&stc=1&d=1501113638

http://forum.tvfool.com/attachment.php?attachmentid=2818&stc=1&d=1501114030

http://forum.tvfool.com/attachment.php?attachmentid=2819&stc=1&d=1501114168

http://forum.tvfool.com/attachment.php?attachmentid=2820&stc=1&d=1501114294

[jrgagne99]

So I have the opportunity to borrow a 70-foot boom-style man-lift to do some painting and roofing jobs around the house. While I have it, I figure I might as well put an antenna as high as I can in one of my tall pine trees. My TV fool report indicates about a 2.5 dB improvement in WFFF at 75 feet in the pine tree, vs. 30 feet AGL on my roof. I plan to vertically stack two HDB8Xs to get the most bang for my buck. With that stacked configuration, in the hottest hot spot on my roof, I have never been able to get better than 20% reception reliability for WFFF. I'm hoping I'll do better than that up in that pine tree.

My plan is to mount the two HDB8Xs onto a mast and then use conduit clamps to bolt the assembly to the tree. I will cut limbs as required to get a clear view to my Mt. Mansfield towers.

My question is in regards to pre-amp selection. From the antenna, down the tree, and into the house, this will be about a 300-foot run. I'm concerned about the voltage drop in terms of supplying power to the pre-amp. Is there a certain pre-amp that is well suited to such a long run?

Also, reliability is a major concern. It could be a long time (or never) before I have access to the lift again, so I also want a pre-amp with low odds of failure.

Finally, are there any mods I should make to the HDB8Xs to minimize chance of failure? I'm thinking mainly in terms of the baluns on this, but maybe there are other aspects I should be concerned with.

Thanks you guys.

[rickbb]

Combining 2 antennas is hit or miss, sometimes it works as planned, sometimes it no different than one, sometimes it makes things worse. The sad part is, no way to predict which one you will get, you have to try it and see.

Also a vertical stack makes the vertical aiming very critical, as it makes a very narrow beam width in the vertical direction. You will need a method of adjusting the vertical angle in 1 degree increments to fine tune it.

I would take a small TV attached to a long extension cord up in the lift with you to use to fine tune your aiming. It's critical you get it right since you won't be able to get back up there again.

[ADTech]

Also, reliability is a major concern. It could be a long time (or never) before I have access to the lift again, so I also want a pre-amp with low odds of failureMount the preamp down closer to the base of the tree so you can reach it if needed. The small sacrifice of noise figure is worth it. Same goes for tall towers. That was a lesson learned the hard way.

My TV fool report indicates about a 2.5 dB improvement in WFFF at 75 feet in the pine tree, vs. 30 feet AGL on my roof. Micromanaging the elevation in the TVFool simulator, especially with 2-edge signals, is usually not a productive use of time. It's my hands-on observation that 2-edge signals, when actually measured, can differ from the calculated signal power by as much as 20 dB. The closer one the receiving antenna is located is to the last diffraction zone in the signal path, the wider the variance can be.

Also a vertical stack makes the vertical aiming very critical, as it makes a very narrow beam width in the vertical direction.A vertical stack would be expected to cut the vertical beamwidth approximately in half, frequency dependent. Since a typical 4 or 8-bay antenna would be expected to have a vertical - 3dB BW in the 30-40° range, the vertical stack of two of them can be assumed to be in the 15-20°. Theoretically, that means there won't be a great deal of reception difference if the incoming signal path is within 7.5-10° of horizontal (assuming the mount is truly vertical). YMMV or, better yet, YAMWV (Your Actual Mileage Will vary).

If using a tree mount, stripping as many branches as you can will reduce sway in the wind (which you don't want). Try to balance the health of the tree, unless you want to sacrifice it to be a pole, with the need to reduce that swaying behavior.

[Tower Guy]

I would expect that stacked antennas in a swaying tree would be counterproductive. The extra gain would help only on calm days. If the height helps, you may not need the extra stacking gain. If you want to try mounting the preamp lower on the tree, I'd suggest a run of RG-11 coax between the antenna and the preamp.

[jrgagne99]

Success! I mounted a DB8e and an MCM-30-2476 in the pine tree at 55-feet AGL and am now receiving all major networks from 70.5 miles (2-edge), even WFFF which is listed on my report to have an NM of about -5 dB. I combined the two antennas with an Antennas Direct UVSJ and confirmed signal strength over a few days at the end of the 50-ft RG-6 coax that leads to the base of the tree. Whereas my best roof-top hot spot only senses WFFF with an SNR=8 dB on average, my new tree-top arrangement is clearly receiving WFFF with an SNR of around 22 dB.

My last steps are the relatively simple tasks of amplification at the bottom of the down-lead at the base of the tree, and then running the coax from the base of the tree to the house. Per the requirements of my "domestic beautification committee", the coax must be routed underground.

I'm looking for any advice on trench depth, cable selection, conduit selection, etc. for completing this underground run of about 125 feet.

Thanks in advance!

[rabbit73]

Nice work on finding a hot spot for your signals.

There are two ways of running coax underground. RG6 in conduit, or direct burial coax without conduit.

With coax in conduit, there are two schools of thought. You can use water tight conduit or perforated conduit in a sand bed for drainage. When coax is run in water tight conduit, it will still be in a pool of water from natural condensation, hence the perforated conduit approach.

Keep in mind that you might have to pull a replacement length of coax in the future. Avoid sharp bends and hard pulls that can damage the coax inside.

http://forum.tvfool.com/attachment.php?attachmentid=2820&d=1501114379

I haven't done it myself, so I suggest a Google research focusing on ham antennas on towers.

If you have a preamp at the base of the tree, then the preamp voltage will come from the power inserter inside. It will be necessary to take into consideration the voltage drop for the preamp. RG6 with a solid copper center conductor will have a lower voltage drop than coax with a copper clad steel center conductor. Since the DC current for the preamp also flows through the shield, quad shield coax has a lower resistance than dual shield coax.

Before digging a trench, lay the coax on the ground for a test to see the results.

[jrgagne99]

A few updates...

I switched the downlead from RG-6 to RG-11 and gained about 1 dB on my worst channel (WFFF). I was surprised at how substantial that RG-11 coax is. I had to bore out the passthrough on the UVSJ enclosure to accommodate. I also switched to a continuous 150-ft length of RG-6 between the bottom of the tree and the house (instead of 100-ft of RG-6 coupled to a 50-ft of RG-59). I was pleasantly surprised to see that gain me about 2 more dB. Finally, I put in the very low noise pre-amp (KT-200, supposedly has only a 0.4 dB noise factor). I believe that gave me about 2dB more over my previous Channel Master CM-7778 pre-amp. So now I’m seeing an SNR of about 23-24 dB at the TV on WFFF. Threshold for reception is about 15 dB, so now I have some good margin. Atmospheric conditions can regularly steal 3-5 dB.

Next steps are to rent the ditch-witch and lay the coax and conduit, complete the grounding, and tidy-up the house-side distribution.

http://C:\Creare_Data\ZMisc\Pictures\2017 Antenna Pictures\DSCF6977.JPG

[rabbit73]

Thanks for the update telling us about the changes that improved the SNR of a weak marginal signal.

The link to your DSCF6977 image doesn't work.

[jrgagne99]

Here are a few pictures. In the second photo, the branches look closer than they actually are. They are a good 15 or 20 feet away. I may do a bit more trimming before returning the man-lift, but it seems pretty clear when I'm actually up there.

http://forum.tvfool.com/attachment.php?attachmentid=2928&stc=1&d=1507303476

http://forum.tvfool.com/attachment.php?attachmentid=2929&stc=1&d=1507303487

2928

2929

[rabbit73]

Thanks for the photos. That lift looks ideal for the job.

Where is that building as related to the house, or is it part of the house?

http://forum.tvfool.com/attachment.php?attachmentid=2930&stc=1&d=1507315892

http://forum.tvfool.com/attachment.php?attachmentid=2931&stc=1&d=1507315892

[jrgagne99]

Where is that building as related to the house, or is it part of the house?

That is my maple sugarhouse, which is part of my barn. The house is located about 100 feet off the left edge of the photo (130 feet between house and tree).

I buried the coax about 18" deep in a 1" black water-pipe and grounded the mast and coax this weekend. I was only able to get about 4-feet deep with the grounding rod, hopefully that is enough.

Question: Does it matter where the grounding block is located, with respect to my Kitz-tech KT-200 pre-amp (upstream or downstream from it). I currently have the grounding block downstream from the pre-amp, since that would be the prototypical configuration if the pre-amp were mast-mounted. But since my pre-amp is at the base of the tree, I appear to have a choice...

[jrgagne99]

I did a bit of research on the mast and coax grounding.

Mast grounding: As I understand it, the main purpose is to prevent static charge build-up at the antenna, thereby reducing the likelihood of a lightning strike. Connection to any decent ground-stake should suffice for this.

Coax shield-grounding: This should be tied to the same ground that the house and its appliances (e.g. my TV) use. Anything else could result in a floating ground or a ground loop.

Therefore, I think I should move my grounding block to the house-side so that I can utilize the house ground-stake, rather than my ground-stake at the tree. Since the entry point of my coax into the house is on the opposite side of the house from my house ground-stake, would it be ok to just connect the grounding-block to the ground-wire (bare wire) of a convenient 110V outlet, such as the outlet that I'm using to power the preamp's power-inserter?

[rabbit73]

That is my maple sugarhouse, which is part of my barn. The house is located about 100 feet off the left edge of the photo (130 feet between house and tree).Thank you. I couldn't figure out where the antenna was located when looking at the satellite view.
Question: Does it matter where the grounding block is located, with respect to my Kitz-tech KT-200 pre-amp (upstream or downstream from it). I currently have the grounding block downstream from the pre-amp, since that would be the prototypical configuration if the pre-amp were mast-mounted. But since my pre-amp is at the base of the tree, I appear to have a choice... You are in a gray area as far as the NEC is concerned. I would treat it like a ham antenna on a tower.
Antenna System Grounding Requirements
http://www.reeve.com/Documents/Articles%20Papers/AntennaSystemGroundingRequirements_Reeve.pdf

A strict interpretation requires a 6 gauge copper conductor between the ground rod at the base of the tree and the house electrical system ground. That would be inconvenient and expensive.

Most hams ground the antenna and the coax at the base of the tower, and ground the coax again at the house to the house electrical system ground. The coax shield then acts as a bond between the two grounds instead of the 6 gauge copper wire.

This is also the method used by many satellite installers. The dish and coax are grounded at the base of a ground mounted dish, and the coax shield is again grounded at the house to the house electrical system ground. The coax used is quad shield that has a lower resistance for a more effective grounding bond. Other dish installers use coax with a 17 gauge copper coated steel messenger wire for grounding the dish, but it is not grounded at the dish.
http://www.dbsinstall.com/diy/Grounding-2.asp

see other parts at that site

Todd Humphrey doesn't speak for the NFPA that publishes the NEC code, but he has some ideas that are helpful. The local electrical inspector (AHJ, authority having jurisdiction) has the final say if you are willing to get him involved. Some inspectors are more friendly than others; a local electrician could tell you.

You get to decide what method to use.

[jrgagne99]

I couldn't figure out where the antenna was located when looking at the satellite view.

The google satellite view is about 4 years old. I built the barn/sugarhouse 3 years ago.


You are in a gray area as far as the NEC is concerned. I would treat it like a ham antenna on a tower.... You get to decide what method to use.

Thanks for the suggestions. I think I will ground the coax shield in both places (tree and house).

[jrgagne99]

Mount the preamp down closer to the base of the tree so you can reach it if needed. The small sacrifice of noise figure is worth it. Same goes for tall towers. That was a lesson learned the hard way.

Thinking about ADTech's recommendation some more, I think I'm going to move my UVSJ from the top of the tree to the bottom of the tree, and use separate down-leads for UHF and VHF. I already have two downleads installed anyway: the original RG-6 downlead and my current RG-11. Extending this line of thought, I think my VHF signal is strong enough that I can get away without amplifying it, and only amplify my UHF feedline. Moving the UVSJ downstream of the amplifier could save me the insertion loss on the UHF side. Does that make sense?

Does the Antennas Direct UVSJ pass power on the UHF side? If not, is there a make/model that does?

[ADTech]

Does the Antennas Direct UVSJ pass power on the UHF side?Yes, it does. ;)

[jrgagne99]

Since it's been pretty quite on the forum lately, I guess I'll report on the two amplification configurations I have tried recently.

Configuration #1: Amplify UHF-only upstream of UVSJ, by utilizing the UHF-power-pass capability of the Antennas Direct UVSJ (VHF stays unamplified)
Configuration #2: Amplify UHF+VHF downstream of Antennas Direct UVSJ

Configuration #1 gave me about a 1 dB stronger signal on WFFF (my weakest UHF station). But it came at the cost of about 7 dB on the VHF channel WVNY, which I had to leave unamplified for that configuration. Even though WVNY shows an SNR of 21 dB at the TV for configuration #1 (15 dB required for reception), I decided to use configuration #2 for now. Either one seems equivalent in terms of reception, and both provide about 6 dB more than the minimum needed for reliable reception of the weakest channel...

Current overall setup:
Antennas: DB8e and MCM-30-2476 at about 55-ft AGL in a pine tree. The DB8e uses 50-ft of RG-11 to base of tree, the MCM-30-2476 uses 50-ft of RG-6. Signals combined at base of tree using Antennas Direct UVSJ, then Kitztech KT-200 preamp, then 150-feet of direct-burial-grade RG-6 to house (in underground conduit, belt+suspenders), then KT power inserter, then 30-ft of RG-6 to TV.

My current actual reception report:
WVNY, Real 13, (TVFool NM=6.6 dB): SNR at TV= 29 dB
WPTZ, Real 14, (TVFool NM=9.2 dB): SNR at TV= 29 dB
WCAX, Real 22, (TVFool NM=8.2 dB): SNR at TV= 29 dB
WETK, Real 32, (TVFool NM=-2.2 dB): SNR at TV= 26 dB
WFFF, Real 43, (TVFool NM=-5.8 dB): SNR at TV= 22 dB


Just out of curiosity, does anyone know if there is a UVSJ that passes power on both ports? If so, does anyone know of a pre-amp system that can power two pre-amps using just one power inserter?

[ADTech]

Just out of curiosity, does anyone know if there is a UVSJ that passes power on both ports?No, but it wouldn't be hard to modify ours so it would do so. It would involve opening it up and soldering a coil between the VHF in and the common port terminals, just like the internal UHF filter is bypassed.

You can also use two SAT/TV diplexers in a back-to-back configuration to bypass a non-power-passing component.

If so, does anyone know of a pre-amp system that can power two pre-amps using just one power inserter? I have both a distribution amp in my attic and a preamp out on the mast running from a single power inserter in my living room. I'd have to go up in the attic and review how I did it, I just threw it together out of what I had in the "junk box" and it probably wouldn't be the "optimized" solution.

[jrgagne99]

I have noticed that after the re-pack, WNNE real-25 from Mount Ascutney (which I believe is a local translator for WPTZ on real-14 from Mount Mansfield) will be entering a channel sharing agreement with WPTZ. On rabbitears.info, this shows as 25 --> Sh. 14 for WNNE.

What exactly does this mean? My guess is that the ch-25 signal from Mount Ascutney will cease, and that the periodically-displayed station-ID overlay for WPTZ will now say WPTZ and WNNE, instead of just WPTZ. Is that right? It doesn't mean that the tower that was broadcasting 25 on Mount Ascutney will switch to 14, which would be big co-channel interference problem, right?

What is the short summary of the reasons behind these so-called channel sharing agreements?

[ADTech]

It means that the station currently transmitting on 25 will go off the air and they will become a "guest" on the "host's" post-repack channel and will be treated like a sub-channel as far as your tuner is concerned.

"Channel sharing" is exactly what it says. There will be two stations on one signal, sharing the bandwidth under the terms of their contractual agreement. The guest will pay the host for the right to use an allocated portion of the channel's bandwidth.

[jrgagne99]

It's weird, because WNNE is already broadcasting the exact same content as as WPTZ 5.1 (NBC). In fact, I think WNNE is a translator for WPTZ. Also, WPTZ already has three channels on its signal: NBC (1080i), CW (720p), and MeTV (480i). Could they squeeze one more sub-channel channel into the signal? Even if they could, it wouldn't make any sense to have two subchannels with exactly the same content.

Clarification: (from Wikipedia)
WNNE serves as a full-time satellite of WPTZ (channel 5), the NBC affiliate for Plattsburgh, New York and Burlington, Vermont. WNNE airs the same broadcast schedule as its parent station, but airs some limited advertising specific to the Upper Valley (Hanover NH area) that is added to WPTZ's programming.

[jrgagne99]

The Channel-sharing arrangement took effect last week. WNNE (real 25, virtual 31.1, NBC) which had the exact same content as WPTZ (real 14, virtual 5.1, NBC) ceased broadcasting from its tower on Mount Ascutney. On WPTZ's bundle, virtual channel 5.2 (CW) is gone- it has moved up to 31.1 on my virtual dial and now shows a WNNE word-mark at the top of each hour. So essentially, WNNE is now a CW affiliate instead of an NBC affiliate. Inspection of the channel 31.1 signal on my Sony Bravia shows it is being broadcast on Real-14 (WPTZ's frequency), which I guess is the essence of channel sharing.

At the end of the day, I personally didn't lose any programming content, since I was receiving both WNNE and WPTZ signals. But anyone who couldn't get WPTZ in my area (the vast majority of folks) essentially lost their NBC affiliate when WNNE stopped broadcasting locally as part of this "Channel Sharing" arrangement. Kind of a bum deal.

[Nascarken]

Yes On the solid signal HDB91 side by side 3ft apart feed line's the same length and
Beside free shipping on the HDB,91 I did and it work's well you will be happy with it
I was!!lol with my 150ft tower receive of channel's was right on the money lol
And yes one feed line for vhf&one for uhf and I suggest you use RG11.for best results.
Lol good luck with your antenna set-up and be safe on the roof and look out for power lines when installing an outdoor tv antenna!!!
PS,or maybe you should just go with the Winegrud,8200U
With a channel master 7777amp..And for get about that
OTHER mess and I am sure you will be happy as a pig,in sht.lol
And up north look out becuse BROADCASTING station for all
Of Boston Mass and so on for Over the aire Broadcasting
That thay say is going too nock your soxs off lol and besides
In this neck of the woods the fcc suggests that you use a combow outdoor tv antenna like the 8200u.I hope this put's
A good spin on things and up north dount for get the channel master 7777amp becuse their is no worries about over load.
With all IT'S Montana and so on lol

[Nascarken]

It means that the station currently transmitting on 25 will go off the air and they will become a "guest" on the "host's" post-repack channel and will be treated like a sub-channel as far as your tuner is concerned.

"Channel sharing" is exactly what it says. There will be two stations on one signal, sharing the bandwidth under the terms of their contractual agreement. The guest will pay the host for the right to use an allocated portion of the channel's bandwidth.
Yes and you should probably start seeing low band vhf as well.
Up north in are neck of the woods in Boston and New York city.And so on
And that is why the Fcc.suggest you buy a combination hi&low band vhf/uh F like the 8200u.
Outdoor tv antennas not just a uhf or hi vhf outdoor tv antenna like the
DB8,the HDB91 and the antennas Direct,91XG,so dount cut your self short
When getting an outdoor tv antenna and I suggest that you use RG,11,for
Best results in installing an outdoor tv antenna,good luck and if you
Dount believe me go to Fcc, .com good luck with your antenna set-up and
What you choose to do.

[jrgagne99]

I'd rather not have this discussion be derailed by antenna and preamp recommendations for a problem that is already solved. My setup is complete and working swimmingly, as described in posts #90 and #98.



Back to Channel Sharing...

Has anyone else experienced a so-called Channel Sharing agreement like what I have described in post #103? One in which, for most people, basically amounts to a station just going off the air? Is this common, and will it be more common as the Repack moves forward?

[Nascarken]

IT'S time too start a new thread ???
All you should probably do is go with Rg11,
Instead of the 6

[OTAFAN]

And that is why the Fcc.suggest you buy a combination hi&low band vhf/uh F like the 8200u.


https://www.fcc.gov/consumers/guides/consumer-faqs-tv-spectrum-auction?from=home

[rabbit73]

I'd rather not have this discussion be derailed by antenna and preamp recommendations for a problem that is already solved. My setup is complete and working swimmingly, as described in posts #90 and #98.



Back to Channel Sharing...

Has anyone else experienced a so-called Channel Sharing agreement like what I have described in post #103? One in which, for most people, basically amounts to a station just going off the air? Is this common, and will it be more common as the Repack moves forward?It is only common for the channels that agreed to that arrangement during the auction. The channel that stays on the air is called the Host (H); the channel that gave up its license is called the Guest (G).

[JoeAZ]

In my hometown of Buffalo, NY, the longtime CBS affiliate, WIVB, turned in their license. They had always broadcast from Colden, NY, which is elevated and about 20 miles south of Buffalo. They are now "channel sharing" with the CW affiliate, WNLO, which broadcasts from Grand Island, about 5 miles
north of Buffalo. Grand Island is just about at sea level. All the folks in the southtowns who received the Colden signal cleanly either receive no signal at all or a very poor signal from Grand Island. In essence, many have lost CBS programming.

[jrgagne99]

I have the opportunity to borrow my neighbor's 60-ft man-lift again this weekend to service my tree-mounted antenna array. This may be the last time I get to do any maintenance up there for several years. I'm planning to re-aim and re-secure my 30-2476 VHF antenna which has been blown off by 45-degrees. I was also planning on replacing some my non-UV-stabilized zip ties with UV-stabilized ones, and putting dielectric grease in the barrel connectors.

My questions are what kind of dielectric grease should I use, and is there anything else I should do while I'm up there, considering I probably wont have access again for several years?

Thanks in advance!

[OTAFAN]

My questions are what kind of dielectric grease should I use, and is there anything else I should do while I'm up there, considering I probably wont have access again for several years?



Hi jrgagne99: I use and would recommend Coax-Seal. It will stay put on your connections as long as you need it and does come off fairly easily when you want to remove it. I've only read a very few posters across the Net not liking it. The link below will give you their information and you can buy it off Amazon as well. (I am in no way affiliated with Coax-Seal. Just a hard core OTA enthusiast offering a tip).

http://coaxseal.com

As far as dielectric grease goes, I use Caig DeoxIT D5 spray to improve conductivity. But that's just been my preference. Although they do have grease too. Someone else may have the "cat's meow" on grease. You can find them at: www.caig.com

Stay safe up there in the trees and please post back your results as I would be interested in seeing how everything came out.

All the best!

[Tower Guy]

Silicone grease is often used on O-rings. That is what Andrew (now Commscope) packaged with their connectors for high powered coax called Heliax. I never bought any silicone grease because I’ve always had some left over. Silicone based O-ring grease is available from Lowe’s.

https://www.lowes.com/pd/aqua-ez-o-ring-lubricant/3152031?cm_mmc=shp-_-c-_-prd-_-lwn-_-google-_-lia-_-241-_-poolproducts-_-3152031-_-0&kpid&store_code=2723&k_clickID=go_1792976560_68785408469_346853782070_pla-416743622626_m_9001946&gclid=EAIaIQobChMIp-P_56S14gIVDuDICh3csQCrEAQYAiABEgK3APD_BwE

[Tim]

I prefer silicone fusing tape to the coax seal. It adheres to itself and fuses together. It leaves no residue when removed. You can simply slit it gently with a razor knife and peel it off easily if you have to remove it. The bond is permanent, waterproof, resists weathering and UV deterioration. It stretches around uneven shapes and forms a really tight seal. I use it for all my TV and ham radio antenna connections. I have opened up connections that are over 10 years old and found them just like the day I installed them. It is really great stuff.

[jrgagne99]

...please post back your results as I would be interested in seeing how everything came out.

I was reluctant to undo the coax connections up in the tree, for fear of messing something up unnecessarily. So rather than take the connections apart and applying grease, I decided to just use the silicone fusing tape that Tim recommended. I wrapped the tape tightly around each coax connection and it seemed like it would be a pretty water-resistant seal. I also replaced some of the zip-ties up there with UV-resistant versions and trimmed a couple of branches while I was there. Hopefully the setup will continue to function well (all five major networks from 72.5 miles away) for many years to come.