Early last year, based on a tvfool report for my location, I chose a CM-2016 antenna to receive the TV stations on Mt Wilson (approx 300 degrees azimuth, 10.5 miles distant). Everything was peachy; I could receive KABC, KNBC, KCBS, KCET, KTTV, KOCE, KDOC, KTLA, and a plethora of foreign language channels. After a few months, KNBC became marginal then disappeared. I also had trouble with KTTV.
Just the other day, I added a 4 foot section to my antenna mast to raise the antenna, in the hope of getting KTTV and KNBC back. I did get those stations, but lost KABC.
By accident, I discovered that I got a very strong signal from KABC with the antenna mast lying on the roof so that the antenna was pointing up at about 20 degrees from vertical. With the antenna mast erect and the antenna boom parallel to the ground, the signal strength of KABC is reported as zero in the channel diagnostic screen on my TV.
Does anyone have a guess as to why I lost ABC when I lengthened the mast? Or why I get good signal aiming the antenna almost straight up? Or what I could do to get it back?
Possibilities: The resistance from the antenna boom down to the ground wire is about 1.5 Ohms. The mast is a rusty 2-piece unit with the top section that slides onto the bottom section. I could probably decrease the resistance of that path by cleaning all the corrosion off the contacting pieces. Is ground resistance of the magnitude of 1 Ohm significant for this application?
Being channel 7 and at the low end of the designed operating band of the antenna, reception is going to be marginal and I might get better results with an antenna that covers all of VHF, perhaps even an indoor antenna?
Would angling the antenna boom upward help, since the broadcast antennas are on the top of a mountain? If so, is there readily available hardware to change the elevation angle?
Original installation (estimated 18 feet above ground)
Raised by 4 feet