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Old 19-Sep-2016, 5:39 PM   #1
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Join Date: Sep 2016
Posts: 226
Reception Help in NH

Please help!

I am trying to pull in the 5 major stations (NBC, CBS, ABC, PBS, FOX) all transmitting from a distance of 70 miles, 342-deg, 2-edge. The stations are WPTZ, WCAX, WVNY, WETK, and WFFF. Here is my report:

Eventually, I would like to feed 3 TVs. Over the last 8 months or so, I have been experimenting with four antennas, all with fairly similar results in one key aspect, specifically, the inability to reliably receive WCAX. The antennas are (Denny's HD Stacker, CM-5020, HDB91X, and a homemade 8-foot K7MEM yagi designed for UHF ch-22).

In general, in 5-foot AGL tests with the TV very close to the antenna (4-feet of RG-6, no pre-amp) and the antenna pointed to 342-deg, I can get WPTZ fairly reliably, with spotty pick-up of WCAX. By "spotty", I mean if I move the antenna 5-feet to the right or left it can make the difference between 40% signal for WCAX and nothing. Oddly enough, in some locations I can receive WCAX at 5ft-AGL, but when I raise the antenna tripod up to 8ft-AGL, reception dies, until I move to the right or left about 6 feet. I have confirmed that this is a spatial anomaly somewhat repeatable from day to day, not a temporal one. Very strange behavior, but I figured it would go away when I permanently mounted the antenna on the roof at 30ft.

Not so. I moved the antenna to a gable-end mount at 30-ft AGL, with a CM-7778 pre-amp and 35-feet of RG-6 and an earth-ground-block for the coax-shield now part of the setup. I figured that WCAX should come in reliably, and I would have a decent shot at the rest of the channels on my list. Well, I am able to get WPTZ, WVNY (Hi-VHF, so only receives via HD Stacker and CM-5020), and WETK reliably, and even occasionally WFFF (especially with the HDB91X). But regardless of antenna, I cannot seem to get WCAX reliably, even though it has a relatively easy NM=8.2 dB, compared to the other UHF stations that I am receiving that are lower down on the list WETK (NM=-2.2) and WFFF (NM=-5.8).

WCAX is a priority for me since it is CBS affiliate and it carries the local NFL team. Why am I not receiving WCAX? I have a few ideas, such as (1) my down-lead comes in right underneath my electrical meter, and (2) a transformer is about 100-feet away from the antenna at about 325 degrees. Could either of these be causing interference? Any offending trees are at least 300 feet away, and about 50-feet tall. If this is a multi-path "null", would an antenna with a wider capture area (e.g. DB8e) improve reception of WCAX? I suppose I could try mounting the antenna somewhere else on the roof (either on the garage gable ends, or on the middle of the roof ridgeline using a tripod) but the wife thinks it is least-offensive on the gable end of the house, since it is "balanced" by the chimney on the other end of the house. I prefer not to mount it to the garage roof, since doing so would impede reception of some other lower-priority channels to the southeast.

Thanks in advance for any help you can offer!
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Last edited by jrgagne99; 19-Sep-2016 at 6:10 PM.
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