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Old 1-Nov-2014, 8:59 PM   #20
Antennas Direct Tech Supp
Join Date: Jan 2010
Posts: 2,941
I'd like to take a closeup look at your precise location.

Follow the instructions in the fist three paragraphs of this post, then spot the marker on the location on your rooftop s accurately as possible where the 91XG is located. Then copy and past the coordinates that are under the lower left of the map to me in a private massage if you don't want them published in the clear to anyone. I don't need (or want) a plot, I need a very precise location so I can look at your surroundings, especially terrain and foliage in the direction of Springfield.

Swap out the Skywalker for the LNA100 up in the attic. It's got the best noise figure and overload characteristics of any of the amps you have on hand, but it mus be indoors only unless you make an outdoor enclosure for it and provide power. If your coax from the 91XG to the attic amp is more than 25l long, then it would be better to use the RCA as the amp with a very short (3') lad between it and the antenna.

On channel 49, your SNR is only 18 while digital reception, requires 15-16. It's teetering right on the edge of the "digital cliff" and it doesn't take much natural signal variation to push it over the edge into failure. Swapping the LNA100 for the Skywalker *should* improve SNR by 6+ dB and putting the AC7 back in in place of the splitter should pick up another 2-3 or so.

My suggested sequence of connections if using the RCA would be: 91XG > AMP (set to SEPARATE) UHF input > downlead >power inserter>AC7 ch 49 INPUT. The other input of the AC7 would get the C2V signal.

My suggested sequence of connections if using the LNA100 would be: 91XG > downlead (as short as possible) > LNA100>AC7 ch 49 INPUT. The other input of the AC7 would get the C2V signal.

I can tell you from practical experience that not every reception issue can be satisfactorily resolved. Often, one hits the limit of what can be reasonably or willingly done and it's finally time to accept the results. My own home's location (back side of a tree-covered hill) causes the summertime loss of reliable reception of several of the UHF channels from the antenna, but I've just learned to accept that they will be back come November. It does feel better when you stop beating your head against the wall, you know...
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