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Old 13-Jun-2013, 7:04 PM   #26
Pete Higgins
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Join Date: Apr 2013
Location: California, 58 miles @112 degrees from Mt. Wilson
Posts: 83
HDB8X multi-directional? w/dual amps.

329049,

Quote:
I substituted the cheap combiner with a transformer type and picked up 3Db
I write off-line and then post. I didnít 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 donít 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 channelís SNRís. Disconnecting either panel from the combiner caused the other panelís channels SNRís 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 didnít 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 Ėduh!

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 Iím still missing channels. I was too worn out to keep going so I went in and ate ice-cream and watched TV with whatís-her-name. I donít know if this will give me a final solution but it definitely improved my situation dramatically. So, until youíre better paid, thanks.
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