RF interference from my neighbor's HAM Radio

[Another Window]

Greetings,

I just started playing my '78 Mark 1 through a brand new Fender Blue Jr amp w/ a Boss Super Chorus pedal.

Last night, I started picking up my trucker neighbor's HAM Radio signal.

I cannot play while this... guy... and his trash talk are coming through my fresh speaker.

I know there can be many issues:
un-shielded cables,
Un-shielded pickups,
My friend suggested un-grounding with an adapter...

What do you think?

* This is my first post, let me know if I just broke any rules

[Ben Bove]

An interesting read with your exact problem:

http://www.audioholics.com/audio-video-cables/bulletproofing-your-system-from-interference

[David Aubke]

An enduring memory from my youth was listening to the "Red Dragon", an avid CB operator about three doors down, on our FM radio.

That article on Audioholics recommends shielded speaker wire. I thought that was a no-no. I thought the shielding introduced capacitance or changed the impedance or something like that. And I thought that interference in a high-power line such as that going from the amp to the speaker wasn't an issue.

[pnoboy]

Shielding speaker wires should not cause any problems.  Of course, given how short the connection is between the amp and speaker in a combo amp, it probably isn't going to help either.

[vanceinatlance]

I would vote for shielded cable as a good thing if your equipment is properly grounded. And check if your ac outlet is properly grounded with one of those little ac plug testers. If that doesn't work, It could be picked up by the pickup coils in the piano. A Dyno my piano type shielding under the lid might help. Maybe try some aluminum foil wrapped under the lid and run a wire from it to a ground point on the harp to see if there is a difference.

[pianotuner steveo]

Not to nit pick, but I think his radio is a CB and not a HAM. I don't know if there is a difference interference wise, but there likely would be a difference in the kind of language you hear. HAM radio operators have licenses and are more likely to be civil. Anyone can buy a used CB these days without a license.

When CBs were a big fad in the '70's there were so many people using them, that you would get interference all the time in my area. I was probably somewhat guilty myself, but my radio was very low powered. ( with a pretty big antenna) I could only reach about 2-3 miles.

[pnoboy]

A good experiment would be to unplug your piano from the amp, and then see if you can still hear the interference.  If not, then plug in just the shielded cable--no piano attached.  Doing these experiments should tell you if the interference is coming from the piano, the cable that interconnects the piano and amp, or just the amp itself.

Also, I found this schematic of a Fender Blues Jr--http://support.fender.com/schematics/guitar_amplifiers/BluesJuniorIII_schematic_Rev-D.pdf
You could try soldering in a 100 pF capacitor between the right end of R2, which is the grid of V1-B, to ground.  Put the cap as close to the tube as possible, and make sure the connection to ground is short--if you can't find a suitable ground connection, try soldering the other end of the cap to pin 8 (the cathode) of the tube.  Because of the cathode bypass capacitor, this spot is an a.c. ground.  This cap will not affect the sound of the amp, but will be able to short r.f. to ground.

[Tim Hodges]

I would suggest adding a microphone into the mix and giving him some trash talk whilst you play.

[drpepper]

When I bought my Rhodes suitcase it had foil taped to the inside of the harp cover, I asked the owner is to reduce hum?
and he said no it was due to the club he regularly played at the stage was the same side of the venue as where the taxis waited to pick people up outside.
The taxi radios would get picked up by the piano and the radio would play over the PA.

I believe he said this worked so I would try that for cheap easy fix