Hello again:
http://www.tvfool.com/?option=com_wr...8d17611d6780d5
Here's the problem. I want to get a reliable signal for KQTV Ch. 7 out of St. Joseph. Some background. Initially I tried a single YA 1713 without a pre amp at 32 feet off the ground (15 feet off the top of the roof) and got nothing. When I added a Titan 7777 pre amp I was able to get a SNR reading of around 14 to 15db on my TV's Signal Strength Meter. Not enough to get a solid lock without a picture breaking up. BTW. I am only driving one TV and don't use a splitter.
Last November I mounted and coupled two YA 1713's with a CC7870 and the same pre amp. I noted a marked jump in Signal Strength to about an average of 20db on the Signal Strength Meter on the TV. Mast height did not change with the top antenna still at 32 feet off the ground. Total cable run is around 60 feet from the antenna to TV. RG6 quad shield is being used. At this point the picture was fine for several months. Antennas are properly spaced and cables cut to spec per a Winegard Tech.
Fast forward to mid April. Suddenly my 20db signal strength on Ch. 7 dropped several points to around 15 to 16 DB on the SNR reading on the TV's Signal Strength Meter. One suspect is the leaves on the trees. Another thought that crossed my mind is that water got into the coax even though I used a good quality tape recommended by broadcast engineer friend to seal the connectors. Now I rarely get a picture that does not pixelate all the time on Ch. 7. I can usually get a watchable picture if I lock in at 16 to 17db on Ch. 7.
In light of this I've decided to make some changes up there. Eliminate more connections because more problems can arise than with a single antenna. I built a wooden support system around the chimney to hold the current coupled antennas and I should be able to add two to five more feet on top of that along with a rotor and a single antenna. This seems to be the only spot on the property that will get Ch. 7.
Since all of my KC UHF channels will come in with any Yagi I use and KMOS TV from Sedalia comes in with any antenna pointed in that direction I've decided it would be best to replace the current YA 1713's with a single antenna to receive Ch. 7 to 51. My research has noted the VHF Hi sections on antennas like the HBU 55, 7697p and 7698p offer more gain on Ch. 7 than a YA 1713. And since I can mount a single antenna such as this a bit higher I do gain more signal according to the TV Fool report. Even mounting a antenna only 3 feet higher than the current 32 foot level will yield another .4db of gain on Ch. 7. I could probably get it up to 37 feet if I used a small antenna like an HBU 33 or 7694p.
Since UHF reception is not an issue I am only concerned with obtaining a reliable signal on Ch. 7. Eliminating the two channel setup will result in a bit lower loss in the shorter cable run with less connections plus the loss associated with the coupling unit. I figure if I can gain about 2db more signal either through shortening the cable run with a single antenna in combination with a antenna that has at least 1 to 2 db more gain on Ch. 7 than the YA 1713 then I will be in business.
I looked at Ken Nists' HDTV Primer modeling of various antennas and noted the YA 1713 in the real gain test only had about 7.1db of gain on Ch. 7 vs. what Winegard reports in their spec's on the website. Even the Antennacraft HBU 44 is a good full DB higher on Ch. 7 in his test! And this gain figure is accurate with the same figure being quoted for this antenna on Ch. 7 on the Antennacraft website. Antennacraft apparently does not inflate its spec's. The HBU 55 is rated at 9.6db gain on Ch. 7. The 7697p is rated at 10.9 by Winegard and the 7698p is at 10.4. Not sure how accurate the Winegard figures are.
What do you think? Would I be better off using a smaller antenna like a 7694p or HBU 33 at 20 feet off the roof at 37 feet off the ground or would a larger antenna like the HBU 55 or 7697p at perhaps 16 to 17 feet off the roof or about 35 feet off the ground be more apt to give me a little more gain and a reliable signal from Ch. 7?
Regards,
Billiam