DIGIWAVE ANT-7288 Super HDTV Digital 8-Bay Antenna UHF

[be236]

Anyone know about this antenna?

http://www.summitsource.com/digiwave-ant7288-super-hdtv-digital-8bay-antenna-uhf-adjustable-multidirectional-db8-outdoor-high-gain-20-36-db-360-degree-heavy-duty-design-70-mile-8-element-ch-21-69-uhf-hd-tv-aerial-blue-zone-part-ant7288-with-50-ft-coaxial-cable-p-9544.html

Specifications:

DIGIWAVE ANT-7288
Digital UHF Outdoor HDTV Antenna
8 Active Element
Frequency Range: 470 - 862 MHz
Channels: 21 - 69
Antenna Gain: 20 - 36 dB
Beam Width H/V: H 60/ V32
Front-back Ratio: 22 dB
Output Impedance: 75 Ohm
Antenna Length: 820 mm

20-36dB antenna gain! Too good to be true?:confused:

[ADTech]

http://forum.tvfool.com/showthread.php?t=1559

[Dave Loudin]

Dude, you need to focus on the antennas we recommended or consult the antenna chart at digital home. Don't go chasing after clones of dubious quality and dubious claims.

[be236]

Dude, you need to focus on the antennas we recommended or consult the antenna chart at digital home. Don't go chasing after clones of dubious quality and dubious claims.

Yeah, I know... It's just that I'm on the deepest fringe edge of reception here that I find the highest gain UHF as possible and been reading on the various sites and just stumbled on that one. Hence I'm just asking a lot of questions right now..;) The claimed gain was just too good to pass up and ask.

Yes, I need to look at the antenna chart at digital home (if I can find its link again).

[oldjake135]

i have installed one , i think it works well , i live in Beaverton ont canada we are in the boon docks , i get all can stations pluse pbs bufflo and other american stations i also was told they are not any good.:)

[be236]

What channels can you get that show negative NM dB value?

[oldjake135]

ill check it out to morrow and let you no , all canadian cnal. are around 100, percent that i get.

[be236]

Yeah, I'm interested to know... I want to get some channels with NM -8dB to -15dB which are about 130km away...

Also, another question.. the gain listed seems way too high (too good)... so does this antenna come with its own power pre-amplifier? If so, that would make sense for them to claim this "high amp gain," and not "antenna gain."

[No static at all]

With such bloated gain figures, I would personally stay away from this product. They must have been smoking some pretty good stuff to come up with those huge numbers.:eek: Don't see any mention of amplification.

[MisterMe]

i have installed one , i think it works well , i live in Beaverton ont canada we are in the boon docks , i get all can stations pluse pbs bufflo and other american stations i also was told they are not any good.:)The DigiWave ANT-7288 is constructed using two 4-bay antennas mounted side-by-side with each side independently adjustable. To say that it does not work would have been a gross overstatement. I am sure that it is no worse than any other 4-bay antenna, but no better than any other 8-bay antenna. Those who are unfamiliar with TV antennas may be impressed with its performance. By way of comparison, a ChannelMaster CM-4221HD (http://www.channelmasterstore.com/Digital_HDTV_Outdoor_TV_Antenna_p/cm-4221hd.htm) 4-bay has average UHF gain of 10.2 dB. Its larger sibling, the ChannelMaster CM-4228HD (http://www.channelmasterstore.com/Digital_HDTV_Outdoor_TV_Antenna_p/cm-4228hd.htm) 8-bay has average gain of 12.0 dB. The DigiWave (http://www.summitsource.com/digiwave-ant7288-super-hdtv-digital-8bay-antenna-uhf-adjustable-multidirectional-db8-outdoor-high-gain-20-36-db-360-degree-heavy-duty-design-70-mile-8-element-ch-21-69-uhf-hd-tv-aerial-blue-zone-part-ant7288-with-50-ft-coaxial-cable-p-9544.html) claims a gain over Channels 21-69 of 20-36 dB. I can see only two possibilities for such dramatic gain figures for the DigiWave. One is that the laws of physics are different for DigiWave. The other is that they are simply adding the dB levels of the two 4-bay sections. Suffice it to say, you can't do that [correctly].

Even though DigiWave's gain claims are false, it probably still does a decent job of pulling in UHF channels. It is the Ginsu knife phenomenon. For those old enough to remember the Ginsu knife infomercials, the Ginsu miracle knives could cut though tin cans and then cut tissue-thin tomato slices. The secret of the Ginsu knife is that it was stainless steel. Any decent stainless steel kitchen knife could do what the Ginsu knife did.

In a like manner, any decent 8-bay antenna will be as good or better than the DigiWave ANT-7288.

[oldjake135]

mine is a 8 bay antt. i get cblt sinal strengh 45, vall. 100, global :eek:sg. 56 val. 100 percent , tvo sig. 40 , val. 100, 23 buffalo sig .35, val., 100 , ckvr sig., 60 , val 100., chch sig 39., val 100 ctv sig., 60 val.,100 pbs only at night sig., 50,. val 80 percent most come off cn tower wich is about 70 miles away

[claudeM]

I agree that 36 db does not make sense. They must be quoting the front to back gain ratio.
Someone in marketing must have mixed up the engineering data in the translation.

[claudeM]

Back of the envelope antenna-gain calculation for an 8-Bay antenna compared to a single dipole:
Each time we double the number of dipoles we get 3 dB more gain.
Two dipoles = 3 dB more gain
Four dipoles = 3+3 dB more gain
Eight dipoles = 3+3+3dB more gain
Add an other 3dB when we add the reflector then the total 8-bay antenna with reflector = 12 dB better than a single dipole. (this is assuming all dipoles are adding in phase)

[Emu25]

I hav'nt tried the ANT-7288 but here's where you may be able to get it at a cheaper price,
http://www.homevisiontech.com/hdtv/outdoor-antennas/360-degree-adjustable-multidirectional-super-8-bay-hdtv-antenna.html

[Pete Higgins]

Solid Signal had what appears to be this same antenna advertised this weekend as a “Solid Signal Xtreme Signal HDB8X High Definition Blade 8 Bay Xtreme Antenna (HDB8X)” for $59.99 with $0.05 shipping.

I don't believe their dB claims either, but for $60.04 delivered, I ordered one to try. Depending on how well engineered their matching harness is, I expect it to be in the ball park with any other 8-Bay.

I have a 40 year old Channel Master CM-4228 8-Bay Bow Tie up right now on a push-up mast and a 9 month old 91XG up on a 40' tower. Solid Signal expects to ship around the 1st of June (2013?) so when I get it I'll swap out the 4228 & (unscientifically) compare performance.

I can’t tell much difference between the 4228 & the 91XG with two notable exceptions; the 91XG reliably receives channel 43 (2.1 CBS) but has a hard time with channel 36 (4.1 NBC) and the 4228 reliably receives channel 36 (4.1 NBC) but has a hard time with channel 43 (2.1 CBS). The SNR for the rest of my UHF stations is usually within 1-2 dB with slightly over half favoring the 91XG.

[Pete Higgins]

As promised by Solid Signal, my $60.04 delivered HDB8X 8-Bay Bow Tie Antenna arrived this afternoon. It was double boxed in a heavy duty brown corrugated cardboard outer box and a thiner white corrugated cardboard inner box. The two 4-Bay panels were stored back-to-back in the white box with the cross beams loosely assembled and tie wrapped to them. There was also an assembly & installation manual and one rubber boot in a plastic bag.

The assembly & installation manual “What's Included” section lists:
(2) Mast Clamp Braces
(2) Regular Braces
(2) Sections of Antenna
(3) Weather Boots
(I only received one boot but that is all that is needed. Each length of 4-bay panel BALUN to combiner coax came (loosely) attached to their respective panel's BALUM and had a boot installed on each end.)

If you know how the antenna goes together assembly is straight forward, tool-less and easy. As with a lot of assembly manuals, however, the three listed steps (A, B & C) were not intuitively obvious. Fortunately, the manual listed a link to an assembly video: http://www.xtremesignal.com/hdb8x.html that can also be found on YouTube @ http://www.youtube.com/watch?feature=player_embedded&v=BWfW1ncmOr4 (Thank you Mike!). I would strongly suggest that anybody assembling this antenna for the first time watch the video. FYI, to make mine look like the one in the manual & video I had to unscrew the combiner, rotate it 180 deg. and reattach it. Also, to have all the wing nuts on the back side of the antenna I had to reverse a number of the lower brace bolts. Fortunately, both sides of the metal mounting brackets (square tube clamps) have square cutouts to keep the plated carriage bolts from turning.

I am impressed with the way this antenna is designed. First off, the 16 individual 8” elements appear to be stamped from 1.66 mm (~0.065”) sheet aluminum. The matching harness inter-connecting the 16 elements appear to be formed from a relatively heavy 3.88 mm (~.153”) aluminum wire. Each element is held in place and in contact with the matching harness by a Phillips head screw into the plastic stand-off. This means that after a few years service when oxidation forms, unlike my Channel Master 4228 that has the wire elements riveted to plastic brackets, I should be able to remove the screws and clean all the contact areas. The element to harness contact area is a generous 11.12 mm (0.437”) wide. The BALUN is also bolted to the harness making all pressure contact areas accessible for cleaning. The 32 round through boom reflector tubes are 8.18 mm (0.322”) thick X ~19 ½ long. They are capped at the outer ends by a curved plastic extrusion that may mask progressively longer (~1”) rods at the center of each 2-Bay panel. The square supporting tubes measure 18.38 mm (0.723”). There is a lot of hardware provided to build this antenna that appears to result in a relatively robust design.

When fully assembled, the overall antenna is 32 1/2” tall X 47 7/8” wide X ~5 1/4” deep.

Hopefully, this weekend I'll have time to get it mounted and on the air.

[tripelo]

...I am impressed with the way this antenna is designed. First off, the 16 individual 8” elements appear to be stamped from 1.66 mm (~0.065”) sheet aluminum...

Thanks Pete, for your assessment of the 8-bay construction.

The length of the elements seems encouraging. That 8 inch length is comparable to the 'original' CM-4228, so the antenna should have better low UHF response than say the DB-8 (6.5 inches as reported here (http://www.antennahacks.com/Comparisons/CM4228_vs_DB8_vs_HD8800.htm)). Also, the stamped flat element may have slightly better bandwidth (less SWR across the band) than the commonly used wire elements.

...Hopefully, this weekend I'll have time to get it mounted and on the air.

Yes, looking forward to your findings.

[Pete Higgins]

OK, I got the HDB8X together last night & couldn’t resist trying it.

By holding it up @ ~4’ AGL in my downstairs dining room, hooked to my computer’s Hauppauge HVR-1800 tuner I am able to watch two UHF channels from San Diego, channel 19 (69.1 KSWB) and channel 40 (39.1 NBC). These channels are both 88 miles @ ~166 deg. which means the signal is coming through the whole house. Pointed it towards LA (51 miles away) and got channel 36 (4.1 KNBC) with a SNR of 22.1, channel 31 (5.1 KTLA CW) with a SNR of 15.6 and the few others that I tried until my arm got tired. Maybe tonight’s just a fluke, but truthfully from down here, I didn’t expect to get anything other than channel 26 (24.1 KVCR) the PBS station 3.5 miles away.

[Pete Higgins]

I do not claim to “scientifically” test or even fairly compare multiple antennas. I can, however, report my real world results, recognizing the constraints I’m faced with. Make what you will of the information. I can confirm that lugging antennas and climbing ladders was a lot easier 50 years ago. It must be something in the water?

Since I can’t raise or lower my pushup mast by myself, I fixed mounted the new Solid Signal HDB8X on it below the rotor. The bottom of the HDB8X is @ 21’ 7” AGL, 5’ 9” below the bottom of the 40 year old Channel Master CM-4228 (not a new “HD” model). For the last several weeks, the CM-4228 has been connected through a new white 17’ RG-6 cable to the base of the pushup mast, an F-81 F-F barrel, 50’ of new white Magnavox M61210 RG-6 to a coax switch in the garage. My Winegard YA 1713 was similarly connected through a new black 17’ RG-6 cable, an F-81 F-F barrel to a 32 year old piece of RG-6 that also ran to the coax switch in the garage. During amplifier testing I verified there was no SNR variance @ UHF frequencies between using the new white vs using the old black garage coax runs.

I disconnected the black garage RG-6 cable from my YA 1713 and used that piece for testing the new HDB8X. The garage coax switch was used to switch between the CM-4228 & the HDB8X. The single output of the garage coax switch is connected to a new ~75’ thru-wall RG-6, run to my office computer and Hauppauge HVR-1800 tuner card used for this comparison. In other words, everything from the coax switch in the garage to the point of measurement was common for both antennas.

Using the rotor, I “bump” aligned the CM-4228 for maximum SNR on LA channel 36 (4.1 KNBC) and then, by eyeball, “fix” aligned the HDB8X to match. I purposely did not try to introduce the variance of two separate amplifiers although looking at my TV Fool report amplification is certainly called for: http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d1dda169109ca5c

The HVR-1800 was tuned to a channel & the SNR recorded, I then ran to the garage to throw the switch, returnd and record the new reading, tuned to the next channel, record it and repeated the process. Measurements were alternated between antennas so that each antennas value was recorded 20~30 seconds apart.

I also included measurements from my <1 year old Antennas Direct 91XG/Antennacraft Y10-7-13. These antennas are tower mounted @ ~40’ AGL and have individual +15 dB PCT MA2-M drop amplifiers connected via either an F-71 M-M barrel for the 91XG or a 300 ohm to 75 ohm BALUM and short piece of RG-6 for the Y10-7-13. The output of each amplifier connects to a UVSJ feeding ~125’ of new RG-6 that connects in my garage to a PCT MA2-4P +8dB/output per leg distribution amplifier one leg of which feeds a separate new run of RG-6 into my office. A different HVR-1800 tuner card & computer were used to take these readings. This is clearly an apple to oranges comparison, but is in-part justified by the fact that when I swapped the 91XG & CM-4228 last summer there wasn’t a significant difference in amplified performance. If nothing else it should be predictive of what I might achieve by adding a +23 dB amplification chain to the HDB8X and mounting it on the tower.

http://www.digitalhome.ca/forum/picture.php?albumid=1146&pictureid=7002
http://forum.tvfool.com/attachment.php?attachmentid=549&d=1372562936
If it were still made, I would certainly recommend the Channel Master CM-4228 over the HDB8X if for no other reason than its High VHF capabilities. Within its design frequency range the unamplified HDB8X average UHF SNR of 13.975 compares favorably to the 13.7429 of the unamplified CM-4228. .23 difference is well within my margin of reading error since the tenths digit for both antennas was constantly changing. Had I been able to align the HDB8X with a rotor I may have been able to improve its SNR, especially for the San Diego stations. Last summer when I swapped out my brand new tower mounted 91XG with the CM-4228 I was really surprised when it matched the 91XG SNR’s within 1-2 dB on all channels. The 91XG was better on slightly over half of the channels but the CM-4228 definitely held its own. For that test I replaced the 91XG’s F-71 M-M barrel to PCT MA2-M connector with an ~18” piece of coax to the CM-4228’s 75/300 ohm BALUN keeping the amplifier, UVSJ and coax paths to the measurement computer fundamentally the same for both antennas. Extrapolating those results to today’s tests leads me to conclude that at my location there isn’t a significant UHF performance difference between the three antennas.

[Pete Higgins]

A compelling advertised feature of the HDB8X is its ability to align the 4-Bay panels to receive broadcasts originating from different directions. Since I predominately watch UHF stations coming from San Diego @ ~169 deg. (True) and Los Angeles @~292 deg. (292 – 169 = 123 deg.) I thought I would see how well it performed when configured with the panels orientated at a 123 deg. angle.

Similar to what I did yesterday, using the rotor, I “bump” aligned the CM-4228 for maximum SNR on San Diego channel 30 (15.1 KPBS) and then, by eyeball, “fix” aligned the non-movable HDB8X panel to match. I then “bump” aligned the CM-4228 for maximum SNR on LA channel 36 (4.1 KNBC) and then, by eyeball, “fix” aligned the movable HDB8X panel to match.
FYI, I had to tighten the wing nuts on the mast clamps until they were vertical to align the movable panel. To go more than ~130 deg. you’ll probably have to shorten the mast clamp bolts on the moveable panel side.

While I got my normal 3 San Diego UHF stations, I thought I had a bad panel pointing towards LA. Other than my local channel 26 (24.1 PBS TVFool @ -15.6) I couldn’t receive any LA stations. After several trips to the roof to check connections & alignment I decided to disconnect the LA panel from the combiner and use it like a standalone 4-Bay. I connected the combiner end of the HDB8X harness through an F-81 F-F barrel to the black coax used for testing yesterday. Configured standalone, I got channel 38 (30.1 ION) with an SNR in the 15.x range. Usually anything below 16.x isn’t watchable for very long. Clearly to be useable I was going to have to add an amplifier.

I connected the combiner end of the HDB8X harness through an F-81 F-F barrel to a 15’ section of RG-6 coax. I connected this new length of coax through a Channel Plus NF-471 55dB channel 24-29 notch filter to my Winegard AP-2870 amplifier’s UHF input. Configured this way I got 13 of the 19 channels I had yesterday. As expected, I lost the San Diego channels and all but one (PBS) of those in the NF-471 notch.

Pleased with the amplified single panel results, I reconnected the HDB8X harness to its combiner input and connected the 15’ section of RG-6 coax to the combiner output.

http://www.digitalhome.ca/forum/picture.php?albumid=1146&pictureid=7010

Combining the two antennas resulted in the total loss of 9 LA stations and dramatically reduced the others. Based on today’s testing results, for my location, the HDB8X is a competitive 8-Bay Bow Tie when used in its “flat panel” configuration but is nearly useless for leveraging its advertised multi-direction feature.

http://forum.tvfool.com/attachment.php?attachmentid=550&d=1372563023

I suppose one advantage it still has over a conventional 8-Bay like my CM-4228 would be the ability to use it as 2 separate 4-Bays and run separate cables to a coaxial switch?

I also ran a series of tests substituting a PCT MA2-M +15 dB cable drop amp for the Winegard AP-2870. The Channel Plus NF-471 notch filter was not used with the MA2-M.

[tripelo]

A compelling advertised feature of the HDB8X is its ability to align the 4-Bay panels to receive broadcasts originating from different directions.

Combining the two antennas resulted in the total loss of 9 LA stations and dramatically reduced the others. ...nearly useless for leveraging its advertised multi-direction feature.

Thanks Pete, for testing this feature. I’m sure that you know this:

There are at least three fundamentally different ways of combining all channels from two antennas. Each involves two or more significant sources of S/N loss.

In all cases, if the antennas point in different directions there is:

- Loss of the stacking gain (up to ~ 3 dB) that the antennas might have (assuming transmission lines matched).

Additional Loss for Each Case:

Case 1. Separate antennas pointing different directions connected to a hybrid combiner (usual splitter reversed) have:

- Loss through the combiner, typically more than 3.5 dB at UHF

Note: When the signals at the combined (input) ports are non-identical, hybrid combiners have 3 dB additional loss above normal circuit losses. Not-identical signals occur when antennas point toward differing stations.

Case 2. If the signals are combined with transmission line techniques that avoid the 3 dB hybrid combiner additional loss, then there is no isolation between input ports.

Without the isolation; The second antenna loads the first, and re-radiates away ~3dB of signal, vice-versa for the first antenna loading the second one.

Case 3. If both antennas have their separate matching preamplifiers prior to combining, then there is isolation between input ports, so:

* No loss thru re-radiation,
* No S/N loss through combiner (single signal input to output)

This is because both signal and noise have been raised above noise floor by preamplifier, so combiner loss in effect just lowers gain of both signal and noise. Not affecting S/N ratio.

But, now there is:

- Twice the noise, compared to one antenna, one preamp, and no combiner.

This is a result of each preamp adding equal noise power above noise floor. Two independent noise sources adds at combiner output.

Depending on preamp noise figure, this Case 3 could be better, or much worse than the first two cases.

Choose your poison.

Each method has some advantages and disadvantages.

Note: Matching two transmission lines is most important when antennas face same direction. When antennas face different directions, phase control of the two signals is usually lost, therefore matching transmission lines typically does not provide gain.

Note: Further in this thread is attempt to add more detail.

-----------------------------------------------------
Diplexers such as a UVSJ, or a Join-tenna, get around some of the S/N losses mentioned in Cases 1 thru 3 by providing lower-loss frequency dependent isolation.
-----------------------------------------------------

I suppose one advantage it still has over a conventional 8-Bay ... use it as 2 separate 4-Bays and run separate cables to a coaxial switch?

Yes.

[Pete Higgins]

tripelo,

I knew some of what you mentioned in your last post but definitely not all.

When I assembled the antenna, I noticed that the coax was unusually thin and very flexible with rubber boots and molded connectors installed @ each end.

Yesterday, I decided to document the coax harness and test it and the supplied combiner (by substitution). Fortunately, the coax was marked as 3C-2V, which made looking up its specs. relative easy. It is just another form of 75 ohm coax.

http://forum.tvfool.com/attachment.php?attachmentid=537&d=1371494504

I was surprised to find a ¼” difference in length when measured from screw-on edge to screw-on edge. First, I substituted two length matched 36” pieces of RG-6 between each of the HDB-8X’s BALUN's to the combiner. Worst case loss for 34” of 3C-2V@ 700 MHz = ~.268 dB and should be insignificant compared to RG-6 @ .217 dB. Needless to say, this test didn’t yield any noticeable difference. Next, I left the RG-6 connected to the BALUN’s and substituted an ordinary 1 GHz 2-way splitter for the combiner. Again, no noticeable difference in SNR.

Here is a picture showing the installation and comparing antenna sizes.

http://forum.tvfool.com/attachment.php?attachmentid=536&d=1371494301

I want to try some ideas suggested by your post but I’ve got to finish refurbishing a CONDO.

I bought a 5 year old 3 Br./3bath CONDO for my wife’s son just after I retired and he trashed the whole place. Just a few more hours work & we’ll have it ready to rent –to someone else. Maybe tomorrow or Wednesday I can get back to playing.

[329049]

I also recently purchased this antenna (HDB8X). I have used the 4228 for a few years and my situation is more difficult than most, 70 miles from the transmitters and in hilly terrain.

Construction of the antenna was straight forward, but I also found it to be weak in physical strength, the reflector end caps came off easily. I was also surprised that the elements were strickly pressure points between wires with screws and plates (no rivets or welds). Here in the Northwest, exposed to allot of water, these points will oxidize and become resistive over time (have already seen this design and used it, with the oxidation results) I doubt this antenna will with stand a 50mph wind (get them in the fall and spring).

Putting the 4228 against the HDB8X with a 10Db (2.7DB NF) amp (have too), the 4228 out performed the HDB8X by about 6Db (measured, I have a RFM 151)
I substituted the cheap combiner with a transformer type and picked up 3Db, but with the 300 ohm to 75 ohm baluns on each bay (HDB8X), it just couldn't match the performance of the 4228.

If I was closer to the transmitters by even 15 miles, and they were in different directions, this antenna would rock, but for fringe, (extreme fringe) it just wont hold up. As a side note the 4228 stand alone is weak also, for me, I must use the preamp, and to bring in a couple of weak stations I have doubled the 4228's (use two of them) into the preamp, allot of plumbing but it works. I did run a test with 2 HDB8X's (yes I bought 2, I had high hopes) into the same situation, and only received half as many channels. Those supplied combiners really bite. (HDB8X)

My next try will be to modify the HDB8X's with 300 ohm combiners (feedline method) and see what happens.

[329049]

I got curious on the combiner. Wow, super cheap, only a 1/2 turn for each leg, good ones will have a min of 2 turns, up to 4 typically. Measured the loss, 4.9Dbm, ouch (before I took it apart)

[Pete Higgins]

329049,

With your own RFM 151, it sounds like you are a lot better equipped to more rigorously test than I am. Depending on your definition of performance, I suppose my SNR equivalence could be masking relatively large differences in antenna gain. I know it’s less important with digital, but I would dearly love to be able to characterize individual channel signal strengths right at the antenna. I’ve toyed with buying a Spectrum Analyzer to do that and to look through the spectrum for interferer’s, but, just can’t justify the $1,000 – 2,000 cost for my “playing”.

My HDB8X, from Solid Signal, assembled seems to be pretty stout. I’ve carried it by the end caps and they don’t show any signs of coming off (well, I’ll stop that now!). We get higher winds than 50 mph here all the time, in fact, we’ve already had a couple of days with 45 mph gusts and it seems to handle that just fine. Do you recall if all the reflector tube lengths were the same or are the tubes longer where they extend into the wider centers of the end caps?

I have a 40 year old 300 ohm CM-4228 (not the newer –HD) and my wire “whiskers” are riveted through plastic stand-offs to the wires interconnecting the bays. Since it is so old, I wish I could take it apart to clean the “pressure points” although performance wise it was still competitive with my new 91XG.

All of my LA stations are 1 & 2 edge @ ~ 52 miles and San Diego stations are 1 & 2 edge @ ~ 88 miles. Oriented towards LA both antennas showed very similar SNR. Oriented towards San Diego the CM-4228 posted 3-4 dB stronger SNR numbers. I thought at the time this was due to not having the HDB8X alignment optimized.

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d1dda169109ca5c

I hope you will continue to report your results and detail any improvements you develop.

[Pete Higgins]

329049,

I substituted the cheap combiner with a transformer type and picked up 3Db

I write off-line and then post. I didn’t see your combiner post until today. Can you tell us the brand & part number of the lower loss combiner you used for your tests? In my location, 3 dB would make all the difference in the world!

tripelo,

I was able to try your panel isolation suggestion yesterday. I don’t have a pair of matched amplifiers so, since the San Diego stations are much stronger, I started with a PCT MA2-M +15 dB drop amp. on the LA panel and the unamplified San Diego panel signal into the combiner. That combination killed all three San Diego UHF stations. As soon as I disconnected the LA panel from the combiner input all three San Diego channels came back strong.

Then I tried the PCT MA2-M +15 dB amp. on the LA panel and a PCT MA-B1010-1PN + 10 dB single output drop amp on the San Diego panel. That marginally brought back the San Diego stations but killed off or lowered all of the LA channel’s SNR’s. Disconnecting either panel from the combiner caused the other panel’s channels SNR’s to improve, usually by 3-6 dB, but one channel even came up by 10 dB.

These PCT drop amps. work wonderfully in a mixed -13.4/-15.6/-100 or lower environment, consequently, they were my first choice. Your isolation point made perfect sense to me when I read it so I was surprised it didn’t work. After I sat down and thought it through, I realized that these are bi-directional cable TV drop amps. and are designed to pass signals in both directions –duh!

Fortunately, I have two runs of coax going to the push-up. I setup 2 power inserters in the garage and combined their output signals. At the mast I hooked my Winegard HDP-269 to the San Diego panel and my Winegard AP-2870 to the LA panel. I connected the Winegard YA-1713 through an Antennas Direct -20 dB FM trap to the AP-2870 VHF input. Things got a little better but I was still missing channels and sometimes would have to retune several times to get lock on a channel.

My last trip to the roof I installed my Channel Plus NF-471 55dB channel 24-29 notch filter on the UHF input to the AP-2870. For the first time ever this completely eliminated RF channel 26 (24.1 KVCR @ -15.6 dBm). My SNR meter pegs out @ 30 dB and two of the three San Diego UHF stations pegged the meter. The third showed 29.5 dB. That was a dramatic improvement. LA reception also appeared to improve but I’m still missing channels. I was too worn out to keep going so I went in and ate ice-cream and watched TV with what’s-her-name. I don’t know if this will give me a final solution but it definitely improved my situation dramatically. So, until you’re better paid, thanks.

[329049]

The combiner was on the HDB8X, with a 1/2 turn explains why there is more than 3.7Db loss.
I understand why they did it this way, converting to 75 ohms on each bay, so they could maintain the flexibility (azimuth), but the loss's add up, I should have my 300 ohm conversion done in a couple of days, will be interesting to see if I get any difference at that point.

[Pete Higgins]

329049

I’m looking forward to your results. I expect the HDB8X factory combiner is attempting to match 37.5 ohms (two paralleled 75 ohm inputs) to a 75 ohm output.

Do you recall if all the reflector tube lengths were the same or are the tubes longer where they extend into the wider centers of the end caps?

Can you tell us the brand & part number of the lower loss combiner you used for your tests? Not the one that came with the antenna.

[329049]

I made a quick 300 ohm lead in, I did use the 75 ohm adapter that was on the antenna as well. Just using 300 ohm into a Diplexer (VHF/UHF) did not work very well.
Overall it gained about 4Db into the RFM151, I compared the stock HDB8X (including it's combiner) to my modified 300 ohm HDB8X (pictures after I post this, because of the delay). I was a little surprised I didn't have a bigger difference, but 4Db when you are in fringe is huge. I also did not use a preamp.
I am figuring there is a better way than the quick way I did the 300 ohm conversion. I have not compared it to the 4228 yet either, but I suspect they will be close to the same. The flexibility of the variable azimuth would give the HDB8X and advantage for those that are closer to the transmitters.
With the stock HDB8X pulling the left side back about 4 degrees, did increase the signal level by 1.5Db, this did not work with my 300 ohm version.
The test was also don at ground level, same mast and coax, just adjusting the antenna for peak readings.
One other note, I tried different lengths of 300 ohm lead in (from the joining to the adapter) and it appears picking a wave length of a channel for the lead in length, will help that channel

[329049]

here are some pic's of what I did.
I use the Wineguard adapters, CC7870 (75 ohm) and SD3700 (300~75)

[Pete Higgins]

329049,

Based on earlier posts and posts in other forums, I thought the DIGIWAVE ANT-7288 and Solid Signal antennas were the same. After looking at your pictures it appears they are not. What I bought was a “Solid Signal Xtreme Signal HDB8X High Definition Blade 8 Bay Xtreme Antenna (HDB8X)” for $59.99 with $0.05 shipping.”

While very similar at a glance, it appears our two antennas have completely different elements and mounting frames. Your elements appear to be made from wire, similar to my CM-4228 while mine are made from much wider 1.66 mm (~0.065”) thick stamped, or die-cut, 8” lengths of sheet aluminum. Please look at post #22 above for a better comparison. This may explain why our CM-4228 comparisons yielded such different results?

The picture you posted of the combiner you opened got me thinking that it might pass power through both ports. I just got down from the roof, after pulling mine off the cross brace. I show open from the case (ground) to all of the center conductors and continuity between all three center conductors. Not knowing this, I ran separate (different length) powered coax’s to each amplifier and combined their outputs in the garage. Later today, I’ll rewire taking advantage of the power passing this style combiner affords. Thanks for sharing that picture.

My combiner is labeled “FREQUENCY MIXER, 470-862 MHz, INSERTION LOSS less than or equal to 4.8 dB”. If accurate, that seems like an excessive amount of loss to incur for combining two 4-Bay outputs, especially in a flat panel configuration, but might explain why you saw so much improvement when you substituted a different type of transformer combiner?

At least if I can amplify each panels signal pick-up before it reaches the combiner it should help compensate for that 4.8 dB of loss.

[Stereocraig]

Very interesting, Tripelo.

Would the isolation provided by one preamp per antenna, also allow for dissimilar antennae and/ or different feed lengths to the combiner?

[tripelo]

Very interesting, Tripelo.

Would the isolation provided by one preamp per antenna, also allow for dissimilar antennae and/ or different feed lengths to the combiner?

Yes, but :)

There are tradeoffs. Some mentioned earlier, but not every detail.

Depends on objectives.

An example:

If the two antennas (either alike or different) are receiving signals of similar power level from different stations, then probably the preamps should be well matched in gain and noise figure. In general, transmission line length doesn't matter (but in specific cases, see below, it can matter).

After combination, if amplifiers are not gain matched, the noise from amplifier with the high gain will dominate the noise floor for both signals. Then the signal from the amplifier with low gain may suffer a noise floor that is higher that it may have had before combination (thus lowering S/N ratio for that particular signal).

As with most things, this (preamp gain mismatch) can either be an disadvantage or an advantage.

If one had a really strong signal, then that particular preamp gain could be chosen to be lower than the preamp for the weaker signal. This could help the weaker signal after combination because the noise floor would not be quite as high as otherwise. This is at cost of some reduction in S/N for the strong signal.

----------------------
Signals received from more than one antenna

If both the antennas (different or not) are receiving appreciable signal power from a desired station, when combined there can be phase interference, somewhat like short delay multipath. Since this uncontrolled phase relationship between signals is somewhat random, odds are that it may not be severe.

For consistent results, each desired station's signal power should be pretty well eliminated from all but one antenna.

Conceivably, one could adjust transmission line length to help phase align the signal from one station that was being received by both antennas.

[Stereocraig]

Thank you Tripelo, for the in depth response.
I am running A/B right now and will probably just add more runs for C/D if I expand.

[tripelo]

Referring to hybrid combiner in earlier post (http://forum.tvfool.com/showpost.php?p=36774&postcount=21):

A hybrid splitter/combiner schematic may look something like this schematic from Mini-Circuits.

- Ports A & B are splitter outputs or combiner inputs.

- Port S is the combined port.

http://forum.tvfool.com/attachment.php?attachmentid=533&d=1371404556

It seems that most common splitters available are not configured as above. To find a splitter with good isolation between ports, it's probably best to look for a splitter with specified isolation. An isolation value between input ports of 30 dB is good number.

Attempting to add clarification to Case 3 in the previous post. Both the TV signals and the noise, being independent, suffer ~3 dB attenuation from one input port to output, or combined port, of the hybrid combiner. This ~3dB loss results from internal circuitry to provide isolation. There are also additional normal circuit losses that ranges from tenths of a dB to a few dB.

Noise power from two independent sources above the noise floor (kTB) is additive in a hybrid combiner. Equal noise power above noise floor at each input adds at output. So relative to signal power, the noise experiences no loss (3 dB loss through single port, plus 3 dB combined gain). The signal has no combined gain since the other input port does not contain that particular signal.

About Noise floor & kTB:

Because of the preamplifier’s gain, the noise power at combiner inputs is above the noise floor.

KTB, thermal background noise is a major contributor to the noise floor at UHF and above. Man-made and galactic noise can contribute to the overall noise floor but mostly these affect VHF more than UHF.

The overall result is that S/N is reduced 3 dB (hence the twice the noise mentioned in the previous post). Different signal frequencies from the separate antennas pointed in different directions do not coherently add in the combiner. Combiner circuit losses affect both the signal and the noise so this is where the gain of the preamplifier in front of the combiner can help with improved signal to noise ratio.

Assuming all three cases utilize identical preamplifiers, with preamplifiers after combiner in Case 1 & 2, then:

In general compared to single antenna, single preamp, and no combiner, all 3 cases lose S/N at combiner output (by about 3 dB plus).

Case 3 differs:

- Mitigates 2nd antenna loading losses (Case 2) and
- Via gain of preamplifiers, overcomes the additional normal circuit losses in the combiner (Case 1). Although they exist, no transmission line losses are assumed in Case 2.
- The noise figure of two preamps must low enough, so as to be a small contributor to final S/N, else Case 3 could make situation worse.

As the example in the previous post (http://forum.tvfool.com/showpost.php?p=36822&postcount=33), All cases have interesting specific applications in which they may have some advantage.

-------------------
Will make a small edit to Case 3 in earlier post (http://forum.tvfool.com/showpost.php?p=36774&postcount=21) to help with clarification.

[Pete Higgins]

tripelo,

I sent you a PM -I think?

Using two amps ahead of the combiner works better than anything else I’ve tried. Unfortunately, my signals are so weak (all 1-edge & 2-edge) that 4-Bays only works when conditions are moderate to good. I'll keep playing.

Is there a way for me to post graphics that will show & stay? Mine seem to disappear.

[tripelo]

Thanks Pete for your interesting PM.

You may post images that will automatically open for the reader by using the BBcode .

Place the following in the post where you want the image to appear.

[IMG]URL link to the image

'URL link to the image' is the exact link you see in your browser when you click to display your uploaded image.

After uploading your image, in the Control Panel, select 'User Options', then select 'Attachments', then click to display the desired image. When your image displays, the URL for the image then shows in the URL address bar in your browser. Copy the link and paste it in above.

To get the URL link to the image in Firefox without displaying image:

Right-click the image attachment title in the Control Panel and select the "copy link location".

Paste this link between the URL designations as above.

[Pete Higgins]

tripelo & all,

A gentleman on the digital home forum (holl_ands) identified the combiner picture that 329049 posted as a “Magic Tee” and posted several links for me to bone up on Magic Tee theory & design. 329049’s would basically be the T2 portion of the Mini-Circuits diagram that you posted and appears to be missing the port-to-port (2 X R) 150 ohm mis-match dissipation resistor (RINT). According to what I read, the 75 ohms on each input port should transform to 37.5 ohms @ the combiner’s output, necessitating the output impedance matching auto transformer T1 (also missing from 329049’s combiner). The only way I could tell if my model has a resistor across the windings would be to de-solder the metal cover, since a 150 ohm resistor in parallel with a couple of inches of wire is going to appear as a short to an ohm meter. Based on my continuity measurements, I can tell that mine doesn’t have a grounded auto transformer on the output side but maybe if I’m lucky its designed something like this:

http://forum.tvfool.com/attachment.php?attachmentid=540&stc=1&d=1371843139

I wanted to show how I have the HDB8X configured for multi-directional reception. At my location, I really need the extra gain of an 8-Bay vs. a 4-Bay but when the signals aren’t faded this configuration seems to work very well –without a rotor. When the signals are faded, even my CM-4228 & amplified 91XG tend to drop in & out.

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d1dda169109ca5c

As you can see from my TV Fool report, KVCR, RF channel 26 @ -15.6 dBm (and an FM station on 99.9 @ -13.4) would severely overload my pre-amps., but all the rest of my San Diego (~168 deg.) and LA (~292 deg.) stations are 1 & 2 edge @ -85 dBm and below. That’s why I added the 55 dB NF-471 notch filter that rejects off-air UHF TV channels 24 to 29 and the Antennas Direct 20 dB FM Band reject filter to the AP-2870 LA panel amp.

http://www.highdefforum.com/members/pete-higgins-albums-antenna-pictures-picture670-hdp8x-multi-setup-3.jpg
http://forum.tvfool.com/attachment.p...1&d=1371843183 (http://forum.tvfool.com/attachment.php?attachmentid=541&d=1371843183)
A couple of things to note are that:

1. I am powering both amps. through the two panel signal combiner that came with the HDB8X.
2. The NF-471 completely removes RF channel 26 @ -15.6 dBm with the LA panel pointed right at that station and the amplified & unfiltered San Diego panel that’s rotated ~123 deg. is also completely rejecting KVCR. I wasn’t expecting this. This panel does bring in RF channel 30 (KPBS @ -96.3 dBm) from San Diego with an SNR in the mid 20’s.

[Pete Higgins]

329049,

I wanted to let you know that while they still could be electrically equivalent, the HDB8X “Frequency Mixer” and the combiner that came with your antenna are physically housed in different cases. This at the least suggests they are supplied by different manufactures.

http://forum.tvfool.com/attachment.php?attachmentid=544&d=1372114840

http://forum.tvfool.com/attachment.php?attachmentid=545&stc=1&d=1372114857

How is your testing going?

[Pete Higgins]

tripelo & all,

I wanted to update my progress to show how I had the HDB8X configured for multi-directional reception. For some reason, I haven’t been able to connect to the TV Fool or FM Fool sites for the last several days. (“the site TV Fool is not responding”)

At my location, I really needed the extra gain of an 8-Bay vs. a 4-Bay, but when the signals aren’t faded this configuration seemed to work very well –without a rotor. When they are, even my CM-4228 & 91XG tend to drop in & out.

http://forum.tvfool.com/attachment.php?attachmentid=547&stc=1&d=1372554970

A couple of things worth noting are:

1. I am powering both amps. through the two panel signal combiner that came with the HDB8X.

2. The NF-471 completely removes RF channel 26 @ -15.6 dBm with the LA panel pointed right at it and the amplified & unfiltered San Diego panel that’s rotated ~123 deg. is also completely rejecting KVCR. I wasn’t expecting this. This panel does bring in RF channel 30 (KPBS @ -96.3 dBm) from San Diego with an SNR in the mid 20’s, so it obviously has good forward gain near channel 26 and very good rejection of it to the rear.

http://www.tvfool.com/?option=com_wr...1dda169109ca5c (http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3D1dda169109ca5c)

As you can see from my TV Fool report, RF channel 26, 294 deg.@ -15.6 dBm (plus I also have an FM station on 99.9 MHz also @ 294 deg. & -13.4 dBm) would severely overload my pre-amps., but all the rest of my San Diego (~168 deg.) and LA (~292 deg.) stations are 1 & 2 edge @ -85 dBm and below. That’s why I added the Channel Plus NF-471 notch filter that rejects off-air UHF TV channels 24 to 29 and the Antennas Direct FM Band reject filter to the AP-2870 LA panel amp.

Subsequent to the single HDB8X multi-direction experiments, I decided to try the CM-4228 in conjunction with the HDB8X. My reasoning being that the theoretical 3 dB of additional gain (~ doubling the signal power) would help compensate during the signal fades that always seem to interrupt the San Diego evening news.

Because it was the only device I’d found that would pass power to both amplifiers from a single coax, I queried Solid Signal about purchasing an additional HDB8X Frequency Mixer. They currently don’t list them for sale, but generously offered to send me one (@ no cost) from an antenna damaged in shipping.

I wanted to reconfigure the test installation to raise the HDB8X above the rotor to the same height as the CM-4228 so I could align its pattern for best SNR but unfortunately I can’t bring down my pushup mast by myself. When originally implemented I had two sons, a teenager and a college student, living at home to help. Now, one lives in Oregon and the other retired last year and lives 60+ miles away. Undaunted, I revamped the test configuration as shown below:

http://forum.tvfool.com/attachment.php?attachmentid=548&stc=1&d=1372554970

As with previous testing, I “bump aligned” the CM-4228 for best SNR on LA RF channel 36 (4.1 KNBC @ -107.4) and using its alignment as a guide, aligned the HDB8X as close as possible to the same direction. (This makes the assumption that as mounted, both antennas have the same radiation pattern –which may or may not be valid.)

After everything was in place & hooked up, with both antennas pointed towards LA, I measured an SNR of 24.7-25.3 for RF channel 36 (4.1 NBC). I also measured a SNR of 30 (as high as my meter registers) for RF channel 26 (24.1 KVCR) the -15.6 dBm PBS station 3.5 miles from my house and in line with all the LA stations.

Next, I rotated the CM-4228 towards San Diego, stopping @ ~168 deg. As the CM-4228 turned I noticed 2-3 dB fluctuations in SNR. I “bump aligned” the CM-4228 for best SNR on San Diego RF channel 40 (39.1 KNSD @ -95.2 dBm). I went back and measured an SNR of 23.1-23.4 for RF channel 36 (4.1 NBC). Interestingly, having both 8-Bays pointing the same direction added an additional 1.6-1.9 dB to the SNR. As with previous testing, with the CM-4228 8-Bay turned 123 deg. away from my local PBS station, it didn’t show any back lobe response. Unfortunately LA RF channel 31 (5.1 CW @ -103.5) falls within the Channel Plus NF-471 notch filter’s skirt and was lost. (Rotating the CM-4228/HDP-269 back towards LA brings channel 31 back without any signs of overload)

UHF signal-to-noise ratios from both LA & San Diego are usually 20 dB or greater and appear to stay about the same as a single 8-Bay when aligned with a rotor. More importantly, with a sample size of three afternoons, my San Diego news station dips from an SNR of ~25 to a low of ~18-19 in late afternoon to early evening. It had been dropping into the low 15.x’s where signal was lost. Most nights it holds the 18-19 and stays error free, climbing back up after sundown.

With my limited evaluation capability, last summer my new 91XG performed only slightly better than my “original” CM-4228. This spring my new HDB8X, similarly, performed slightly better than my “original” CM-4228. Therefore, I have to conclude that for my location there isn’t a significant performance difference between the three designs. It also suggests that the advertised gain is very optimistically over stated. Unlike long Yagi’s or LPA’s, Bow Tie designs are easily mounted to a tower leg or off the side of a house or balcony (J-Pole). Hinged designs, also afford convenient reception of multiple markets where a 4-Bay is sufficient.

Because of their price and observed performance, if I needed to design a system from scratch to feed UHF to multiple TV’s without the inconvenience of turning a rotor to view different markets, depending on TV Fool’s reported values, I’d be real tempted to try an unamplified HDB8X with the panels aligned for both markets. If signals were such that you couldn’t tolerate the “re-radiation loss” I’d order two HDP-269’s to help isolate the panels and overcome combiner, coax & splitter loss. Finally, if signals are really weak, (deep fringe) combining two HDB8X’s with two matched pre-amps. (HDP-269’s in an overload prone environment) might offer a cost effective solution. I did find this Splitter/Combiner which should support powering two pre-amps. through a single coax. lead-in:

http://www.solidsignal.com/pview.asp?p=cp2512&d=channel-plus-cp2512-dc--ir-passing-2-way-splitter/combiner-(cp2512)&sku=782644003417&utm_campaign=base&utm_medium=organic&utm_source=google_base

SNR and antenna gain are not the same thing. I would really like to see gain comparisons and real world test results between the HDB8X that I have and some of the other hinged designs –some costing almost 4 times as much.

[tripelo]

Pete, your work with the antennas and especially the 8-bay is quite interesting.

The images of your setup are very good in that they show a descriptive block diagram of the setup.

There is some loss of S/N before any amplification occurs. Realizing that the reason for most of the loss is the filters and traps necessary to remove both strong FM signals and Channel 26.

Earlier, you mentioned:

The PCT MA2-M’s don’t seem to overload, even without the notch filter.

Probably, the noise figure of the PCT MA2-M is better than either of the WG preamps.

Some S/N might be gained if, for UHF, the PCT MA2-M could be used instead of the AP-2870. Also, if the NF-471 could be placed after the preamp instead of in front of the preamp, it could recover the signal lost in the NF-471. To use the PCT MA2-M would probably require a UVSJ. Maybe something like this:

YA-1713 > FM Trap > AP-2870 >
\
UVSJ > HDB8X Combiner > Power Inserter > ...
HDB8X > PCT MA2-M > NF-471 > /
/
CM-4228 > HDP-269 > /

Most UVSJ (Pico & Holland & some others) will pass DC through the VHF side.
The PCT MA2-M can be powered externally.

In your current configuration (last image in previous post (http://forum.tvfool.com/showpost.php?p=36902&postcount=40)), the gain on the CM-4228 side is less than the VHF/UHF combined side. Maybe this gain imbalance is necessary to have usable signals from the VHF/UHF side, if so then the PCT MA2-M suggestion above may not help because of the lower UHF gain of the PCT MA2-M (relative to the AP-2870).

Note: Previously, you mentioned concern about drop amplifiers being bi-directional. Normally, the forward bandwidth covers the CATV range 54-1,000 MHz. Whereas the return bandwidth is lower than ordinary TV signals, in the range of 5-42 MHz.

------------------

About your earlier comments regarding VHF reception of YA-1713 compared to CM-4228 (http://forum.tvfool.com/showpost.php?p=36642&postcount=16):

The YA-1713 accepts signals from a surrounding region of space (aperture). From the image in your last photo, both the 2-meter ham antenna and the CM-4228 may be interfering with the YA-1713.

Any metal inside an antenna's aperture can affect gain and pattern. The situation is usually worse when the metal dimension represents something approaching a half-wavelength at the frequency of interest.

Realizing that some people use CM-4228 in close proximity with a VHF antenna. Depending on relative positioning, such an antenna arrangement can, and likely does, affect an upper VHF antenna's gain.

The dimensions of a 4228 reflector are in the neighborhood of resonance at VHF, that is primarily how the 4228 provides gain at VHF.

It is conceivable that the YA-1713 could be aiding VHF reception for the 4228, and that the 4228 could be disrupting the pattern of the YA-1713.

Driven elements for 2-meter band ham radio antennas are not far in resonance from VHF-TV (~144 MHz vs 174 MHz). Directors for such antennas are shorter than resonance, so could potentially be a good reflectors for upper VHF.

[Pete Higgins]

tripelo,

“Probably, the noise figure of the PCT MA2-M is better than either of the WG preamps.”

Yes, but just barely. The PCT MA2-M’s are rated @ 2.7 dB average NF, 4.0 dB max. & the Winegard HDP-269 is rated “Average Noise: 3dB”. The AP-2870 is rated “Noise: VHF 2.9 dB / UHF 2.9 dB”. I don’t need the NF-471 or FM traps with any of the PCT amps. They just don’t seem to overload. I run one on each of the three antennas on my TV tower. The 91XG/MA2-M & Y10-7-13/MA2-M outputs are combined in a UVSJ & yes, all three amps are powered through a separate run of coax. I built a plastic box with a LM7815 and 4 chassis mount ‘F’ connectors. Basically, 20 VDC in & 15 VDC goes out to each amp. The FM antenna/MA2-M shares the rotor/mast/power distribution system but uses dedicated RG-6 down lead, PCT MA2-4P distribution amp and through house wiring.

Whereas the return bandwidth is lower than ordinary TV signals, in the range of 5-42 MHz.

You are right about the return B/W frequency range, but when I tried using them behind the HDB8X panels, they didn’t appear to provide enough isolation. Switching to the pre-amps. worked much better. I'll try them again.

http://forum.tvfool.com/attachment.php?attachmentid=551&stc=1&d=1372638257

“…both the 2-meter ham antenna and the CM-4228 may be interfering with the YA-1713”

I’m sure you are right, but I’m running out of antenna real estate. Check out <http://www.highdefforum.com/local-hdtv-info-reception/141103-solid-signal-own-brand-2.html (http://www.highdefforum.com/local-hdtv-info-reception/141103-solid-signal-own-brand-2.html)> posts #20 – 24 for pictures of my antenna farm.

Originally, the pushup mast held the Cushcraft A147-20T 2 Meter beam, Winegard HD-6065 10 Element FM Antenna and rotor. When I decided to “play” with OTA I knew it wouldn’t support everything, so built the OTA TV tower.

My main aluminum crank-up tower supports an 11 meter Wilson Shooting Star that’s been re-dimensioned for 10 meters. It is turned by a tower mounted Alliance HD-73. I have a mast mounted 50 ohm coaxial relay (w/’N’ connectors) to switch it between vertical & horizontal polarization. Since I had the tile roof put on I have to climb the tower to work on that antenna. I was up there last summer and my wife came out, saw me, and went ballistic. That’s in part why the TV tower can be lowered & raised with a winch.

When I moved the FM antenna to the OTA tower, it left too much unused mast on the pushup to resist so I mounted the CM-4228. Worked great for the San Diego UHF stations but propagation had to be good to get 8 and/or 10 so I added a dedicated Hi VHF antenna. Turns out, when propagation is good, they both get 8 & 10 when it isn’t, neither gets them. The YA-1713 just gets them sooner and holds on a little longer.

When I can get some help lowering the pushup mast I want to mount a ‘J’ pole and move the 4228 down below the rotor. The rotor on the push-up is a 40 year old Radio Shack Cat. No. 15-1220 and I don’t think it will handle as long of a mast as I’d need to get proper separation.

Believe it or not, I’ve still got a Cushcraft 215WB Boomer that I can’t find a home for.

Nothing has been done for several days. It was 107 deg. here yesterday and its 105 now.

[Sev]

Great job on the explanations and diagrams Pete.
Very helpful.
How is the project progressing?

[Pete Higgins]

Sev,

My current setup has changed. I’m using (2) Solid Signal HDB-8X’s for UHF instead of the single or dual 91XG’s. The HDB-8X’s are cheaper and gave better results @ my location.
http://forum.tvfool.com/attachment.php?attachmentid=799&d=1410727208

[Sev]

Pete
That picture is just awesome.

One of the questions that you coincidently answered in the course of the thread was if those HDB-8X’s were stackable.

When I first looked at them my first thought was doing what you did.
Then I thought to myself would it be possible to do a verticle and horizontal stack so that the final product would be a barrel.
It would probably be a useless exercise. But it would be interesting to see if a functional omni directional antenna could be created.

What did you end up using as far as the plumbing goes?
Amps, combiners etc.

[Pete Higgins]

Sev,

Read through the following posts.

http://www.highdefforum.com/local-hdtv-info-reception/141103-solid-signal-own-brand.html

I’ve included a lot of test results from when I tried various combinations. I had an extra combiner so I ended up feeding the two panels from each HDB-8x into its supplied combiner and then the outputs of each antenna combiners into my extra combiner. I also tried feeding the cables from each 4-Bay section into a 4-Way splitter with very little difference.

These are heavy antennas (well built) so horizontal stacking (by the time you got proper spacing with a non-metallic support) would be problematic. Vertical stacking isn’t a problem.

[Sev]

Sev,

Read through the following posts.

http://www.highdefforum.com/local-hdtv-info-reception/141103-solid-signal-own-brand.html

I’ve included a lot of test results from when I tried various combinations. I had an extra combiner so I ended up feeding the two panels from each HDB-8x into its supplied combiner and then the outputs of each antenna combiners into my extra combiner. I also tried feeding the cables from each 4-Bay section into a 4-Way splitter with very little difference.

These are heavy antennas (well built) so horizontal stacking (by the time you got proper spacing with a non-metallic support) would be problematic. Vertical stacking isn’t a problem.

I was reading through that thread as well. :)

What I am going to start with is an HD7698P. I would like to find an 8 bay that picks up VHF like your old channel master. It is my understanding from a post that the reflector style of the old channel master is what allowed for VHF capture.

Ultimately just for fun and if possible. I am going to go to a muffler shop that has a tubing bender and have them bend a length so I can mount 2 HD7698P's horizontally.
Then at the center have verticle masts welded centered on upper and lower side of the tubing. Allowing me to mount and 8 bay above and below HD7698P's.

That is the main reason I am interested in the particular plumbing you used to isolate the antennas.

The other thing I need to add to the mix is a cell repeater. Cell phone reception is poor due to being in a hollow.

[Nascarken]

We'll I like the old school LOW VHF ANTENNA what is the mile received on it and no one is making low VHF antennas no more do you have some suggestions on how to make one or blue prints on a low VHF ANTENNA we'll have a good day Pete

[Pete Higgins]

Nascarken,

The top antenna is a 10 element Antennacraft Y10-7-13 to cover the Hi-VHF channels. Antennacraft no longer sells this antenna. The center two antennas are Solid Signal HDB-8X’s, combined for an additional ~2.3-2.7 dB of gain, to cover the UHF TV bands. The bottom antenna is a 10 element Winegard Chromstar HD6065P to cover the FM broadcast band. Winegard no longer sells this antenna. I don’t have any Lo-VHF channels in the two markets I target (Los Angeles & San Diego).

I would have to drop the tower & remove the antennas to get tubing diameter(s), element lengths & spacing’s. I turn 73 next month, it’s been over 100(F) all week and I don’t do as well on the roof as I did years ago. Since none of my antennas are Lo-VHF I hope you’ll understand if I don’t make blueprints.

[Nascarken]

Yes it's ok Pete my be next time, and what do you think about making a ANTENNA ,out of copper tubing 3/8 or 1/2 and my ,ANTENNA set up is the solid signal,2 HDB 91XG stacked side BY side 90Ft high,A G L, 20 & I have 2,STELLAR Labs #30-2476,AT 80Ft,high A G L 20,stacked side BY side, with a Ham ROTOR and,a Johansson amplifier kit that has one vhf in at 30:DB,and Two uhf in at 40:DB,SOLID copper 18Gage RG6 CABLE receive 114miles in New York city and I am in Massachusetts by Boston, now I need a low VHF ANTENNA,we'll thanks again and have a good day Pete,PS stay cool,

[Stereocraig]

Another consideration, would be to drive around and look for some of the full size Channel Master Quantums.
You could leave a note asking if they'd like those "Ugly" antennas removed for free. ;)

If nothing else, you'd have a good foundation by itself, or for your own project.

The only advantage I'd see w/ copper, would be its ease of soldering.

[Nascarken]

Yes I am trying to get an VHF LOW THAT'S on store its an old ANTENNAcarft 13,element's it's in good shape but I Wood like to get 2 OF THEM but that's not possible so I will make one to match it

[Stereocraig]

Sounds like a winner!

[videobruce]

The link in the 10 year old OP is dead, this is current if anyone is really interested in this;

https://digiwavetechnology.com/off-air.html/360-degree-adjustable-multidirectional-super-8-bay-hdtv-antenna.html


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