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Noise in the a/c line - Printable Version

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Noise in the a/c line - Robert - 11-26-2008

I am getting some nasty line noise on the 116b radio. Is there some kind of line filter I could build?

Re: Noise in the a/c line - rghines1 - 11-27-2008

Assume you are referring to noise coming in on the antenna wire. Not aware of any filter for that and is why FM was developed.

Re: Noise in the a/c line - Robert - 11-27-2008

Ok here it goes, When I played it at home, the radio played great. When it was moved to country, the radio now has a lot of line noise.
So I would assume it would be coming from the outlet as line noise. Icon_neutral

Re: Noise in the a/c line - rghines1 - 11-27-2008

Remove the antenna lead and ground it to see if the radio becomes quiet.

Re: Noise in the a/c line - radiomikee - 11-28-2008

If your radio works normally i n one location and picks up alot of noise in another, the problem is probably not in your radio at all. RF interference can be generated from the power lines by transformers, corroded connections, and street lights on utility poles. You can find alot of information on this subjet on the web. If you can locate the source of your RF interference generation the power companies will rectify it, there are ways of locating the noise with hand held directional antennas on VHF bands. A local ham radio operator may be able to help.

Re: Noise in the a/c line - Robert - 11-28-2008

Ok, After a lot of digging and finding we found out that the noise is being developed by none other that the pellet wood stove. We unplugged the stove and all noise went away.
The CC radio also was quiet. Now how do you filter motors or an appliance that produces that kind of line noise?

Re: Noise in the a/c line - exray - 11-28-2008

Wow, there's no end of types of interference generators!

If the thing has a 3-wire plug or connection you may see some benefit by simply bypassing the hot and neutral leads to ground with a cap of about 0.1mf@ 600 volt. In doing so we might be tiptoeing around some issues that get into conflict with the National Electrical Code and Safety Codes so take my comments as a 'theoretical' solution.

-Bill

Re: Noise in the a/c line - Robert - 11-29-2008

exray; Good idea and I am thinking about making a box for the caps. Plug the box into the wall socket and then plug the radio into the box type. I have some nice mov's I can install into the cap box for that added protection. This can fit in a small plastic box with everything mounted on a pc board. Thanks for the Ideas. Icon_razz

Re: Noise in the a/c line - exray - 11-29-2008

I was meaning to put it on the power lead to the stove. The radio already has bypass caps on the AC line but they may be 'too late' once the camel has entered the tent. Try both!

GL.
-Bill

Re: Noise in the a/c line - Robert - 11-29-2008

Ok I can try that for sure. I was kinda wondering about that but hay learning something new everyday is not all bad.
Just a note, When I restored the 116b I did rebuild ALL of the bakalite caps. Kinda messy.
Bob.

Re: Noise in the a/c line - radiomikee - 12-04-2008

THE NOISE CANNOT BE SUPPRESSED BY PLACING ANY CAPACITORS IN THE LINE OF THE DEVICE GENERATING THE NOISE. CAPACITORS IN THE LINE ONLY HELP SLIGHTLY WITH STRONG SIGNALS RECEIVED ON THE OUTDOORS POWER LINES. NOISE IS FREQUENTLY GENERATED BY THE POWER SUPPLIES OF COMPUTERS, FLOURESCENT LIGHTING, ALL SORTS OF ELECTRIC MOTORS (ALL SPARKS GENERATE GROAD SPECTRUM RF INTERFERENCE AS IN SPARK GAP TRANSMITTER). THE WOOD STOVE HAS AN IGNITER OF THE WOOD PELLET. PERHAPS THAT DEVICE WHEN IT IS ACTIVATED GENERATES THE NOISE, OR PERHAPS THE POWER SUPPLY FOR THAT DEVICE. IT REACHES YOUR RADIO AS A RADIO SIGNAL, IN OTHERWORDS IT IS A RADIO ENERGY RECEIVED IN YOUR PHILCO'S ANTENNA, NOT TRANSMITTED VIA THE POWER LINES. MODERN HIGH END RADIOS HAVE VARIOUS NOISE SUPPRESSOR CIRCUITS, BUT THE VENERABLE PHILCO BEING THE CHAMP ANALOG RADIO THAT IT IS SIMPLY PASSES THIS NOISE THROUGH. YOU WOULD HAVE NO SUCCESS TRYING TO FILTER IT AS IT IS VERY BROADBAND. UNFORTUNATELY YOU MAY HAVE TO CHOOSE BETWEEN THE PELLET STOVE AND THE PHILCO AT A GIVEN TIME, BUT AT LEAST YOU ISOLATED THE PROBLEM. THE MOST UNUSUAL ELECTRIC APPLIANCES CAN BE AT FAULT. TURNING OFF ONE CIRCUIT BREAKER AT A TIME IN THE HOUSE WHILE MONITORING THE RECEIVER CAN ISOLATE THE OUTLETS INVOLVED, THEN PROCEEDING TO THE INDIVIDUAL DEVICES IS THE NEXT STEP.

Re: Noise in the a/c line - radiomikee - 12-04-2008

ONE WAY AROUNF THE PROBLEM IS TO USE AN OUTDOOR ANTENNA, LEADING TO A COAXIAL CABLE FEEDLINE, TERMINATING AT YOUR ANTENNA LEADS ON THE PHILCO. THIS CREATES MORE SIGNAL IN THE RADIO FROM A SOUCE AWAY FROM THE PELLET STOVE, WHICH IS CAUSING THE PROBLEM. THE LOCAL RF INTERFERNECE CAN STILL GET INTO THE RADIO IF THE SHIELDING OF THE COILS IS LESS THAN COMPLETE. TRY USING A DIPOLE OUTDOOR ANTENNA LOCATED WELL AWAY FROM THE WOOD STOVE, FED BY SOME CABLE TV COAXIAL LINE. PUT THE SHIELD OF THE COAX ON THE CHASSIS, THE CENTER CONDUCTOR ON THE ANTENNA TERMINAL. YOU MAY BE PLEASANTLY SURPRISED!

Re: Noise in the a/c line - DeckApe - 12-04-2008

Radiomikee brings up an interesting point... are the Philco and the stove powered by the same circuit? Can you relocate the radio to a different circuit?

Re: Noise in the a/c line - Texasrocker - 12-07-2008

caps lock on, on computers, causes abit of interference also, or is it the washing-machine motor on "spin-cycle"? (hee hee) Icon_wink

Re: Noise in the a/c line - DeckApe - 12-07-2008

I watched my roommate's laser mouse cause interference on the nearby television the other day. Go figure.