I'm having some interference problems on analog 7 now. My previous problems on analog 9 seem to be solved with the FM trap on the 7777. 9 has a very clean signal now.

I would like to resolve this issue before KABC moves back to 7 next year. It seems like it would be bad enough to cause a disruption if I don't.

The new noise appears to be electrical. Attached are a few pictures.

Any tips on what to check would be appreciated. I'm assuming the source is within 100' or so. The noise is mitigated when I use the YA1713 vs. my VHF home builds, but I'd still like to find the source.

Thanks,

(The moire patterns - on the 2nd and 3rd pics - are artifacts of the digital camera and can be ignored.)

Hmm. About 20 noise bursts per line, and synchronized with the frame. Perhaps a dimmable fluorescent light?

Hmm. About 20 noise bursts per line, and synchronized with the frame. Perhaps a dimmable fluorescent light?

Definitely looks like A.C.

If it's in my condo, perhaps I will just have to turn everything off and then turn on appliances one by one to see what causes it. I just hope it's not coming from one of the two shared walls I have (the other units).

I remember turning off the attic light, which is fluorescent, but I didn't notice a change.

Could it be from a computer?

Thanks,

Could it be from a computer?

That would be my vote.

It's not power line related, but new florescent lamps use a high frequency switching power supply which could be the culprit.

Another notorious source is a touch sensitive lamp.

Another notorious source is a touch sensitive lamp.

I have one of those, and it causes exactly what is shown in the pics. This is likely the problem. Check your lamps that are plugged into that circuit.

I have one of those, and it causes exactly what is shown in the pics. This is likely the problem. Check your lamps that are plugged into that circuit.

It must be from my neighbors' bedroom. I turned on everything I would normally use and it didn't happen last night. It probably happens when it's partially dimmed?

It could be KFMB-DT San Diego transmitting on channel 7 now. They will move to channel 8 next year.

My problem on 7 seems to have gone away, but I would guess that it was a dimmable switch.

However, 9 is still a problem, though only for laptop use. It seems that the On-Air GT tuner and the Fusion 5 are to blame. I don't know if it is the tuner itself or the ultra-thin USB cables I'm using. There isn't a strong FM station around 93.625MHz locally and other local OTA users don't seem to be having the same problem.

Also, using an FM Trap and a Lo/Hi filter (diplexer) have improved the situation little. Attached are pics before and after using the FM trap and Lo/Hi filter. Using the FM trap made no visible difference.

There is a visible pattern on many UHF channels as well.

I used a TV tuner to confirm that it was the USB tuner/cable putting out noise and not the laptop itself.

I'm going to look for a quality USB cable to see if it helps, but I'm using the ones that came with the tuners.

Analog channel 7 has some interference tonight that I have not seen before (see the attached). It is slowly moving from right to left. I do not see it on any other channels. Up close it looks like a chess board, but the blocks are rectangular.

Last night, some thunderstorms were in the area and it is raining tonight. The thunderstorms produced plenty of noise, even up to 13, but this is different.