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

[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), 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:

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.

“…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> 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.

[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-hd...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]

Originally Posted by Pete Higgins

Sev,

Read through the following posts.

http://www.highdefforum.com/local-hd...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 30B,and Two uhf in at 40B,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-a...v-antenna.html


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