Reception issue Frenchtown, MT
 

The signal analysis for my house

I have the following set up:
HD Stacker Antenna
Winegard LNA-200 Boost XT Preamplifier
5' Mast on Eave Mount
~30' RG 6 Solid Copper Cable
Channel Vision 6 way splitter Split 3 ways with 75 ohm terminators
I have the antenna ground directly to a 8' grounding rod, I also ground my coax to the same ground (through a grounding block) before entering the house .

Problem:
I want to pick up station 23 KTMF; however I do not get it.

I do pick up stations 8.1, 11.1, 13.1 (and I believe 14 which lists itself as 13.1). Depending on orientation generally 60-80% strength for stations received.

I have tried orientating the antenna at magnetic 75°, done the search and picked up nothing. I have also used the Channel Strength indicator in the TV while having it set on 23.1, while manipulating both the rotation and height of the antenna. I have also tried searching for the channel both with and without the splitter in play. In all cases channel 23 is not found on an automatic search, and displays a 0% strength on the channel strength indicator despite orientation/height. Please note the height adjustment is based upon raising it another 2-3 ft from the antenna's current position.

From my understanding of where the broadcast tower is I do not believe I have any visual obstructions. I will try to update with photos from the antenna level either later this week or weekend (when home with daylight).

I have been trying to communicate with the Antenna supplier (Denny's Antenna) to ensure there isn't something off there (or with my assembly).

At this point my questions are:
Do I have the right antenna?
-If so is orientation/height an issue?
-Do I need a different pre-amp?
If antenna is not correct
-What would be a good fit for my needs?

Appreciate any help.
FC

Welcome to the forum, FC:

You do seem to have tried the right things, so a little more experimentation is needed. If you are willing to put a little time, effort, and money into tests to try for ABC and Fox with no guarantee of success, I can suggest some things to do.
Based on your tvfool report, that looks like a suitable antenna because you have VHF-High and UHF signals.
You have tried adjusting aim and height, but sometimes it is necessary to move the antenna location left or right if it is in a bad spot for the KTMF signal. I realize that it isn't convenient to move the antenna location, but there might be terrain obstructions in the present signal path that interfere with the signal.

At my location I was having trouble picking up CH42 because my antenna was facing the wrong direction. It didn't show after a scan, so I didn't know how much stronger it needed to be for reception. I made a temporary setup across the street with a 2-bay UHF antenna, my signal level 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.

http://forum.tvfool.com/attachment.p...9&d=1442620525

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.

Based on those tests, I developed a technique that makes it possible to find and measure the strength of channels that don't show up after a scan, but it requires a signal level meter which most users don't have.

http://www.avsforum.com/forum/25-hdt...l#post22105317

Maybe. Have you tried to scan for KTMF without the preamp? There is such a thing as too much signal if it causes partial overload that wouldn't affect the strongest signals but might harm the weakest signals. It is my understanding that the LNA200 was redesigned to meet the price point of the big box stores, and the specs aren't quite as good as the original LNA200.

The Stacker seems to be working. If there was a problem with the UHF section, you probably wouldn't be able to receive K14IU, but KTMF is weaker and has a 1Edge path because of terrain interference.

http://forum.tvfool.com/attachment.p...7&d=1444864417

Notice that only about 30% of the max power is aimed in your direction because of the directional pattern of the transmitting antenna.

Using other profile software:

http://forum.tvfool.com/attachment.p...8&d=1444865151

You can see how the terrain might interfere with the signal on its way to your antenna. The tvfool report simulation doesn't take into consideration ground clutter like trees or buildings. UHF signals can't diffract over terrain obstructions as easily as VHF signals.

Rabbit73 thank you for the help.

In regards to moving the antenna, I don't have the pieces to do a portable set-up like you demonstrated on the AVS Forum (shown in photo above). However I do have spare cable, and can try a manual re-position on the house.

I have a couple of questions for when searching for a signal in either a different position and/or without a pre-amp.
1) I do not have a portable Sadelco or similar device (it appears Sadelco is no longer producing new products). Is it possible to manually tune a TV tuner to a channel (23.1 in my case) and use the channel strength indicator to get a rough guess on signal strength? Or does one need to go through the tv's "scan" feature for each re-position?
2) If manually re-positioning the antenna on the roof, do I need to prop/secure the antenna or can a person hold it?
3) Approximately how long should it be held at a particular height/rotation to allow for the capture (if using the channel signal strength listed in #1)? Growing up I have a rough idea on how long the old rabbit ears took, but am not sure how things may have changed.

Between work and an earlier sunset, I don't think I will be able to get on the roof to try things out until this weekend. Weather is looking good for then, so I will head up and test things out and try to grab some photos from the mast location.

Please let me know if you think of anything else I should try.

Thanks!

FC

It sounds like you are willing to try a few more tests. You have been so thorough so far that I'm kind of running out of ideas, but I'll stay with you as long as you are willing. Maybe ADTech can think of something that I missed. It might not be possible to do any better with KTMF, but I'm not ready to give up yet.
I understand; I was just trying to demonstrate that moving the antenna might find a location where the signal is better.
Yeah, that makes me sad because they are my favorite. There are refurbished meters available from the repair facility that did repairs for them. I have a 719E which measures down to -35 dBmV, equal to -84 dBm, where most tuners drop out. My newer DisplayMax 800 and 5000 don't measure below -20 dBmV (-69 dBm), so I need to add a preamp before them when hunting for channels that were missing from a scan.

http://i496.photobucket.com/albums/r...G_0144_1_1.jpg

The 719E is on the left, the 800 on the right. The 719E was designed to measure analog signals, but is useful to make comparative measurements of digital signals. There aren't many good meters like the 719E left on ebay. The other tool that can be used to hunt for and measure missing channels is a spectrum analyzer, but they are expensive.
Most TVs require a scan, but some will pick up a missing channel if you enter the virtual channel number or the real RF channel number. You can test your TV by trying each way.

You can also do a scan without the antenna connected to erase all channels and then reconnect the antenna and enter a virtual channel number or a real channel number of a channel that you know you can get to see if it picks it up.
Try to keep it from moving during a scan; secure it or have a person hold it still with a prop.
It depends upon how long it takes your TV to lock on to the signal. Unfortunately, the channel will not show unless the tuner locks on to it. With my signal level meter I can hold the antenna in my hand and watch the signal reading as I move the antenna because the meter can measure a signal even if the tuner scan isn't able to find it.

In post #2 I asked if you had tried a scan for KTMF without a preamp, because of the possibility of partial overload, which affects the weak signals before it affects the strong signals.

Your strongest signal is KUFM with a Noise Margin of 52.7 dB, and a signal power of -38.1 dBm. If you add the antenna gain of say 12 dB, you are at NM 64.7 dB and signal power of -26.1 dB, which might be too much for the LNA200 or the tuner.

http://forum.tvfool.com/attachment.p...2&d=1441462888

Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html

ADTech hasn't yet done any overload tests for the LNA200, but he did do a test of the LNA100 using an Eclipse antenna and a spectrum analyzer in a strong signal area.

Eclipse antenna, no preamp:

http://forum.tvfool.com/attachment.p...7&d=1441052886


With LNA100 preamp. Notice how the weaker signals are damaged first because of the rising noise floor from IMD (Intermodulation Distortion) products that reduce the SNR of the weak signals:

http://forum.tvfool.com/attachment.p...0&d=1441054170

This is what the signals look like with a high quality preamp that is resistant to overload:

http://forum.tvfool.com/attachment.p...3&d=1444229120

The things you might consider trying:

1. Move the antenna to a location that has a better signal for KTMF
2. Use a preamp that tolerates overload and has a low noise figure to improve the system noise figure as much as possible
3. Elevate the front of the antenna because the signals are coming over a hill
4. Use a separate UHF antenna like a DB8e or 91XG (which has a tilt feature) to replace the UHF section of the Stacker and combine it with the Stacker with a UVSJ.
5. Add an FM trap because you have some strong local FM signals that might interfere with TV reception. See attachment for FM Fool report for you estimated location.
http://www.mcmelectronics.com/produc...-FM-88-/33-341

http://www.radioshack.com/radioshack...p/1500024.html

I have no idea if any of these ideas will actually improve the reception of KTMF, but the are all I can think of now.

Sorry, I have no technical data on that antenna. I'd recommend contacting the seller directly for assistance with it.

For what it's worth, I have some fairly strong signals, and I am using a Kitztech KT-200-Coax preamp, and it doesn't overload with an HDB91x antenna (91xg clone, and frequently on sale for $34.99 at SolidSignal. Sign up for their daily deals). My CM-7777 new model version preamp DID overload with the same setup, and stopped me from receiving any UHF channels, with the exception of the very strongest one.

Here's what I would do in your location:

I'd buy this antenna for VHF: http://www.mcmelectronics.com/produc...ductid=30-2475
I'd buy this antenna for UHF: http://www.solidsignal.com/pview.asp?p=HDB91X
I'd then buy this preamp if you need one: KT-200-COAX (right-hand bottom of this page: http://www.kitztech.com/

You then need to buy a UVSJ to connect the two antennas that is power-pass on the UHF side, such as the Radio Shack model. I use this one: http://www.ebay.com/itm/RADIOSHACK-V...UAAOSwYHxWGE1o

FM Trap: http://www.mcmelectronics.com/produc...-FM-88-/33-341

You aim the Stellar Labs VHF antenna at 75 degrees magnetic for your strong VHF channels. KUFM is the only one that's off that bearing, BUT, it's strong enough that aiming away from it is a good thing, and probably will still work to get all. If not, you can try splitting the difference and aim in-between 75 and 125 degrees.

You then aim the HDB91x directly at KTMF at 75 degrees, and put the preamp between the UHF antenna and UVSJ. So, the preamp will only be on the UHF side. If you install and FM trap on this side, the FM Trap needs to be installed between the preamp and the antenna. So, antenna ---> FM Trap ----> preamp ---> UVSJ

The VHF antenna goes into another FM trap, and then the UVSJ on the VHF side, and won't be amplified at all.

The antennas need to be mounted about 3ft apart on the mast, so you may need a slightly longer mast.

I basically have this exact same setup (just a different VHF antenna) and it works perfectly for me. Mine is just reversed in the fact that I only have a single VHF channel, and all the rest are UHF.

I like Mike's idea of a preamp for UHF, but not for the stronger VHF signals, using separate antennas.

You can make a preliminary test with what you have now to see what it will do with KTMF if you limit the Stacker to receive UHF only.

Using Mike's idea:

http://www.radioshack.com/vhf-uhf-go...r/1502586.html

but that will not keep the strong VHF signals that come in on the UHF antenna out of the preamp, so I prefer this which uses the UVSJ to keep VHF and FM out of the preamp:

There is the possibility that if Test No. 1 gives you KTMF, you might be able to modify the Stacker to use the UHF and VHF sections as separate antennas.

Your #3 way wouldn't keep VHF out of the preamp. On the contrary, it would amplify the VHF directly from the VHF antenna side. It would also amplify the UHF side, which is the only side that needs amplifying

Ok, so he does this instead, it would stop any VHF from being amplified, even from the VHF antenna:

So, he'd have TWO UVSJ's, the 1st one on the UHF side only, would be the cheap smaller Pico or Holland type that's power-pass on the VHF side, (which we don't care about since that's not used in this case) That would strip out any VHF signals from the UHF antenna. The 2nd UVSJ (that combines both UHF and VHF antennas) would be the RS one that's power-pass on the UHF side, and combines both UHF and VHF antennas.

Rabbit73 and MikeBear, thank you both for the help.

I tested the TV tuner tonight (clearing the channels as Rabbit suggested) and found that it will display an actual channel's strength even if the channel is not located in the scan (i.e. I can set it to 23 without running through a scan, and it should show strength).

Sorry to rehash your comments, but want to try and make sure I got things straight in my head before I play with things this weekend.

For this weekend, I most likely will not be able to get access to any parts currently not in my possession (our Radioshack closed down earlier this year, and I'm not sure if Bestbuy would have this stuff).

First option would be to disconnect the pre-amp, and see what I get, with the antenna turned to magnetic 75. (I take it the magnetic listed on TV Fool takes into account the declination for my area). If I show some signal here, then it is likely the pre-amp is the biggest problem. If I still get goose eggs, then it could be that we need more power, there is obstruction, etc....

Second option would be to play around with the location of the antenna. This could indicate that there is an obstruction or other problem. Angling the antenna on the mast could also help.

Third option would be to disconnect the VHF antenna from the UHF on the existing antenna and see if it picks up anything.

After exhausting these options we go into the 2 antennas whose signals are merged. If I end up going this route, you both suggest filtering out the FM signal on both sides (bummer since we've been using that signal to listen to radio on the mixer), only using a higher quality pre-amp on the UHF side. The setup would involve the cheaper UVSJ to filter out errant VHF signal from the UHF antenna, and then would use another UVSJ to combine the signals. I'm not quite sure what to look for in that second UVSJ that has the UHF pass - if someone could post or message me with what I should be looking for there it would be appreciated.

If I decide to go the two antenna route is there any reason I cannot use the EZHD antenna (I had it up the past year, and only upgraded to try and grab the KTMF signal) to grab my VHF signal? I've used it the past year to get KUFM, KPAX and KECI.


Again, I appreciate all of the help from folks.

Thanks

FC

PS I'm hoping I just need to upgrade the Pre-Amp ;)

I posted a hyperlink to the exact Radio Shack UVSJ that has power pass on the UHF side. You'll have to order it from an Ebay seller (that's where I got mine, as my local RS store wanted TWICE the price for it!), or find a Radio Shack that still has one. Or, you can order one from an Amazon seller, or buy the model that Rabbit posted a link to.

As for disconnecting the preamp you presently have to try that option, you must take it out of the circuit completely. Just disconnecting power to it doesn't bypass it.

Personally, IF you want to try just replacing the preamp and leaving everything else the same, the Kitztech KT-200-Coax model may be your best bet. I originally ran both my UHF and VHF antennas through that method (up until this last weekend) like Rabbit's "Test 3", and it seemed to work just fine with the Kitztech with NO overloading that I could tell.

Here's a link to the cheaper Pico UVSJ to put right after the UHF antenna. http://www.solidsignal.com/pview.asp...UVSJ%29&q=uvsj

The EZHD antenna may work ok for you for VHF only, IF you run it through the VHF side of a UVSJ to filter out UHF signals.

Appreciate the help MikeBear.

I understand the pre-amp disconnect, and that shouldn't be an issue since I can use a single line splice at the mast, and connect directly to the tv in the house.

For the second UVSJ I will look for Radioshack Model #15-2586.

If I go with the KT-200-Coax, I believe I need to provide protection from the elements. In your case, did you use an OTC product or modify a telephone or other junction box?

Thanks again.

FC

You are correct, Mike. The VHF should be added after the preamp.

I blew it.:o:)

I bought and used one of these. http://www.homedepot.com/p/Commercia...4-CE/205727789 I screwed a flat plate on the back/bottom, and used a couple hose clamps to clamp it to my mast under my antennas. It has enough room for the Kitztech, FM Traps, and even the UVSJ if you choose to put them all in the box.

I drilled a couple holes on the cover as needed to pass through the coax, and sealed it with 'Coax Seal' where the coax's pass through. You can buy that from Solid Signal also. It's a moldable plastic material, that resembles black tar. It seals connections tight and waterproof, YET, it can be peeled back off when you need to. One of the greatest products that was ever invented!

I blew it originally also, because I forgot to mention the Pico UVSJ to strip VHF from the UHF antenna. You caught that, and you were right to mention it. I'm sure you would have caught the mistake this morning and fixed it, it's just that I stay up the entire night and saw it first.

The OP was still posting, so I figured I'd mention it quick to help eliminate more confusion.

Yeah, I did stay up late too, which made my thinking fuzzy.

Early this morning in bed my thinking got to the point of saying to me: "Hey, that VHF antenna has gain, so you need to attenuate the VHF signals." But, I hadn't quite arrived at the point you did.

Thanks for being so gracious.

You are getting good at signal analysis.

Hi Folks,

I got up on the roof this morning and played around for a couple hours with things.

Disconnected Pre-Amp
- No change at current mast location (0 strength)
- Found a portion of the house above the garage where it did receive signal (~40% strength) enough to pick up football with no issues.
Re-connected Pre-Amp in this new location
- Increased strength by ~10% (to 50+%)

I then moved incrementally around the roof varying the antenna height/orientation. This exercise demonstrated:
- A band (10-20') wide on the roof where I picked up signal. This band tended to be weaker the higher I raised the antenna from the roof, with a sweet spot being ~3' above the roofline. As I got to the fringe of the area the dropoff was quick from ~30% to 0%.

Since the Pre-amp increased my strength previously I left it connected and disconnected the VHF antenna. I then incrementally moved around the roof with the antenna. Strength levels were similar to what they were when both were connected; however there may have been a slight gain.

Upon completion of the testing I re-installed the antenna on the existing mast and took photos from two vantage points that are attached.
Existing Mast Location (Current Mast Location.jpg)
Where I picked up KTMF (Pickup Location.jpg)

Based upon my experiments I'm thinking my set up has some combination of the following:
1) Poor mast location for KTMF
2) Inadequate UHF antenna
3) Potentially inadequate gain/pre-amp

Moving forward it would appear I could
A) Install a mast where I can pick up signal (This option would require a lot of work on my part, require mounting/runs on a roof that may need to be replaced soon, and could upset neighbors)
B) Experiment with a different Pre-Amp to increase gains at current location
C) Experiment with merging 2 different antenna signals at current location

Options B & C have the definitive risk of doing nothing if current mast location is in a blind spot.

In performing the tests I found it very strange how there was such a limited window (with the existing antenna) where I could reliably get signal, and that raising the antenna much above the roof-line seemed to generally hurt reception.

I guess my questions are:
1) Is there a good explanation on why raising the antenna would hurt reception? (I thought KTMF was LOS, for which higher is better)
2) What is the likely hood I can pickup signal at my existing mast location by playing with antenna/pre-amp choices?
3) Is there any additional tests that I can do with my existing equipment to help provide clarity?

Again, I appreciate all the time and help that folks have put in to this point.

FC

Thanks for the test results and the interesting wide-view photos.

Did you insert a UVSJ for Test No. 1 in post #8?

If you use the UVSJ for that test, you don't need to disconnect the VHF section of the Stacker because the UVSJ attenuates VHF and FM.
The signal wavefront is non-uniform and has layers of weak and strong areas. One possibility is roof reflections of the signal that add to the direct signal that enhance it if they arrive at the antenna in phase.
Another location sounds better; sometimes the best location for the signal isn't the most convenient. But don't give up on the present location until you have completed all the options suggested by Mike.

Your existing antenna location has the roof in the foreground below the antenna. The new location has bare ground. The signal is reflecting off the ground and reinforcing incoming the signal.

To understand why, read this: http://www.hdtvprimer.com/antennas/siting.html

Especially this section:

"The ground reflection can be very helpful. Assume the power in the incident wave is P. If the reflection is 100% efficient, you might expect the power in the overlapped area to be 2P. But instead it will vary from 0P to 4P. (Power is the square of voltage. Where the voltage doubles, the available power goes up by 4.)

If you can put the antenna in the most intense spot, it will collect 4 times as much signal as with no ground reflection (assuming a 100% efficient ground reflection)."

Thanks for the input.

Rabbit73, I do not have a UVSJ thus the disconnect.

Tower Guy, thanks for the info & link. Its been a long time since I had a physics class looking at waves and their resonance/dissonance effects from reflections ;). However, the diagrams make a great explanation on why I had a vertical band. The reflection off of the pavement would also explain the lateral distance that I was able to get feed.

So what this seems to be telling me is that there could be KTMF signal at my mast location, but without the added strength from the reflection the antenna doesn't pick it up.

My current pre-amp (Wineguard LNA-200) specs say it has an 18 db gain. The Kitztech that Mikebear uses has a gain of 24db. It would appear that switching pre-amps could provide up to 30% boost in signals at my current location; however that may or may not be enough with the current set up to "get" a signal. From Tower's post it would appear that the band that I got signal could have been up to 400% of the signal that is hitting other areas of the house.

Question:
1) Would I be correct in thinking that just changing the pre-amp will not be enough to get signal at my current mast location?
2) What numbers do I need to get from the Stacker manufacturer on its UHF gain to be able to compare with other UHF on the market? (i.e. if they tell me that its UHF gain is ~10 db then I would think I need something 20-30db gain to pick up a signal at my current location).
3) Is there any way to estimate what the strength level was when I picked up the signal (and thus allow me to reverse engineer what I may have at the mast)?

Appreciate all the help.

FC