HFU HF Underground
General Category => General Radio Discussion => Topic started by: flexoman61 on November 02, 2016, 1547 UTC
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My neighbor has been a Ham operator for years.
He told me that his next door neighbors have recently
started complaining that his Ham Radio transmissions are
interfering with their Satellite TV and cordless phones.
He operates on 40 meters and always under 50 watts.
He uses a recently installed 1/2 wave dipole antenna,
made with good quality materials, coax ect., that is at
least 100' from any of their houses.
He knows what he is doing, he is a Air Force HF/VHF radio
communications tech. He insist his rig and antennas
are in good working order.
He says it's not likely that his station is causing interference
at such a low freqs. and power compared to the higher freqs. used by Sat. TV and landline phones.
I think he is probably right and his neighbors are probably
tired of seeing his antenna, which was the first complaint a while ago.
So, is this interference described possible?
Thanks
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without knowing whether the antenna is a multi-band or single band, without knowing the brand of radio being used and without knowing the type of coax he is using and whether or not he has a choke balun placed at the antenna would make an answer to your question difficult.
being that satellite and (modern) cordless phones are way up there in frequency, i would say its more than likely not possible that those devices are suffering interference from his HF station but again, i have seen some very strange things an HF station can do if the gear does not "agree" and "unite" together but appears to work properly to the user.
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Yes, it absolutely is possible that his ham transmissions on 40 meters are the source of interference on cordless phones and sat TV. However if his antenna and coax are I good shape, and the SWR is not unreasonable, it is less likely to be the cause.
Part of the issue here is how poorly some consumer electronics handle RFI/EMI. Even though sat TV and cordless phones operate at much higher frequencies than the 40 meter ham band, something in their operation must be at lower freqs. Baseband, IF, video, something has to be at lower freqs, since you can't do everything in the way of detection/interface/display/sound at the higher RF freqs. And these lower freq internal operations would be somewhat susceptible to such RF.
If he is indeed the source of the interference it is probably going to be because of things like poor shielding or poor filtering in the consumer electronics.
In general he should probably do everything he can to insure he is not the source, double check the antenna and grounding, see what the match is like, etc. After that see if he can fid any correlation between his operating times and their interference. If he knows he was not on when they say they have interference then you know the source is not him. If he knows he was on when they had interference, and when he ceased operation the problem went away, then he knows he is the source.
Depending on his relationship with these folks, if all else fails and he is sure his stuff is OK, point to the FCC Part 15 sticker on the back of the consumer device (the sat TV or cordless phone, not the ham gear). It probably says something along the lines of "This device complies with Part 15 of the FCC Rules. Operation is subject to the following conditions; (1) This device may not cause harmful interference, and (2) this device must accept any interference received including interference that may cause undesired operation."
Yeah, it is a Richard Cranium kind of thing to do, and a very last resort, but when all else fails, and you know it is their inadequate shielding or filtering and not your problem, and you have tried to work with them to correct the issue or to confirm the source, they are the ones with the problem, not the ham transmitting.
I had to resort to that one time, when a neighbor complained of me interfering. I worked for months, made many efforts to work with him and to confirm I was or was not the source, and he could never confirm the problem was happening when I transmitted. I know for a fact that I was not transmitting at least a couple times he had the problems, but I was turning my antenna rotor during troubleshooting. But he insisted on blaming me, he saw the antenna moving and assumed I was transmitting, when in fact there was not any radio connected to coax at that time. By the way, he never had a "problem" until I put up an HF beam...of course he had never noticed the wire antennas that had been up since before he moved in two years before that beam went up. And the wire antennas ran more or less along the property line, while the beam was at the far side of the property.
T!
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it is possible but it don't matter.
neighbors stuff is part 15, it must accept interference that causes undesirable operation.
so to be frank, if the neighbors are just being dicks, then let them eat fishheads.