This is partly a post about RFI, partly about antennas.
I just installed a brand new Alpha Antenna 10-160m JPole Sr (
https://tinyurl.com/2x9slkvu) at my suburban Los Angeles QTH. The feed end is elevated and sloped down as per manufacturer's instructions, and SWR is pretty good, as advertised. This is my first time on the air at this QTH.
On all bands I have a continuous white noise at S8-S9, everywhere, all(*) the time. (*="all the time" is not exhaustive; I have not systematically checked yet at all times, but every random time I have tuned in, the noise is there.) I started reading articles and watching YouTube videos about tracking down RFI sources, etc. I shut down the power to my entire house at the main breaker, operated the FT-897D from a battery and saw no change, so it doesn't appear to be anything that I am generating. I was struck by one HAM who found his noise source was a wall wart in his barn, 40 feet from his antenna. As I am surrounded by neighbors, any one (or all) of them could have any number of wall warts (or plasma TVs or grow lights, etc.) and I am not going to be able to help that.
I decided I would try the MFJ-1026 Noise Cancelling Signal Enhancer. It is still on order, due to arrive next week.
Meanwhile I'm setting up the aux noise antenna that will be used for the 1026 noise reference. One HAM I saw (
https://youtu.be/ott_k_C2b_U) used the Russian made active MiniWhip antennas so I thought I'd give it a try. My miniwhip (
https://transverters-store.com/whipinbox.htm) is installed on a plumbing vent pipe using a wooden stand off so that the PCB is above ground, as instructed. There is a wire to the PCB ground plane that I can connect to the vent pipe (instructions say this antenna must be high and must be grounded).
Now here's the thing-- if I leave the miniwhip ground wire disconnected, then I have the SAME RFI (same white noise sound, same S8 level) as my AlphaAntenna. But if I connect that ground wire as instructed, the noise on the miniwhip completely vanishes! *AND* I hear signals! Switching back and forth between the Alpha and the (grounded) miniwhip, I can pick up the same stations, only better, because there is no noise. So this $23, 7-inch long "junk" antenna appears a better receiver than my $200 60-ft "good" antenna.
I don't have the MFJ-1026 yet so I don't know yet how well it's going to work with cancelling my noise but clearly it seems I'll want to operate the miniwhip ungrounded, since that seems to allow it to pick up the same noise, and if it's quiet then it's probably not going to be a good noise reference for the 1026. But the fact that connecting the miniwhip ground wipes out the noise has me more curious as to what the noise mechanism might be here, that grounding could make it go away. Does that mean that I could do something to my AlphaAntenna to make its noise go away? Maybe it's something peculiar to the miniwhip that I don't understand.
Incidentally, linked here (
https://postimg.cc/Wt4z7DNR) is an arial view of my QTH antenna farm. North is up, East is right. The red line (0) is the AlphaAntenna. The feed end is supported with a non-conductive 8 ft mast attached to a sewer vent pipe. At (1) is the mini-whip. At (2) is a 2m/70cm J-Pole mounted to another vent pipe. At (3) is a ground rod and my radio operating position.
Thanks,
Dave / N3WTK