I have the most maddening issue with the broadcast noise put out by the 3G stuff all around me at work. is it possible to shield an existing tabletop radio from this? I also have the issue with a new powered Subwoofer getting the same damn thing. My googling on the subject has turned up nil thus far.
Sure, put the radio inside a faraday cage; no more interference!
Admittedly, this plan has the one tiny flaw that it also won’t pick up the radio station either.
It may be though, that the interference you’re hearing is actually being picked up by something other than the antenna though - perhaps it’s one of the amplifier stages that’s picking it up (which can happen even in non-radio-related equipment, such as computer speakers). In that case, shielding the set (earthed tinfoil should do it), but leaving the antenna sticking out (and not touching the tinfoil) might work.
If not, it would have to be an external antenna mounted somewhere away from the sources of interference, such as the roof.
Probably not. Anything that you do to keep the 3G signals out of the radio will keep the radio stations out of the radio. If it’s got an internal antenna, it’s hopeless. If it’s got an external antenna, about all you can try is re-positioning it, but the 3G is so pervasive, there’s really not much to be done for it.
For the subwoofer, you might have some reduction in interference if you coil the signal cable into a loop right at the input jack. Radio Shack sells snap-on ferrite “cores” that might also help.
If you’re handy with a soldering iron, you could also try making a cable from twisted pair wire - just pull a pair out of a scrap of Cat5. I successfully banished a TV station from a subwoofer this way - the transmitter was less than a mile away, and the sub would hum in sync with the picture’s overall brightness.
Depends on where the hash is coming in to the affected equipment. If it’s primarily through the power cables or other external cabling (such as remote controls, speaker wires or interconnect cables but excepting antenna cables), you can snap on ferrite chokes to try to reduce or eliminate the noise. If the noise is coming in through the antenna, you MAY be able to filter it out, depending on the operating frequency. For example, an FM radio operates between 88 and 108 MHz. There are bandpass filters that you can install on external antennas that will pass ONLY this band, and block out everything else. If the antenna is built-in, you’re mostly out of luck in this case. And if the noise is digital hash on the same operating frequency as the affected equipment, you’re also out of luck. All you can there is try to move it and see if an different location is less electrically noisy.
I’d suggest getting a copy of The ARRL RFI Book.
An FM bandpass filter can keep non-FM signals from entering the antenna input.
Shielded speaker wire can prevent speaker wires from acting as unintended antennas.
AC line filters can prevent RF from entering via the AC cord.
There is conductive spray paint that can be used to add shielding to plastic enclosures.
Not legally, at least from the factory.
Read the “Part 15 of FCC Rules”, which I’m sure is printed on the case somewhere…
Is that even what it means? That little sticker has perplexed me for decades.