Amp Picks up CB Radio

Ben Feher · From: Austin TX

If I turn the gain on my amp all the way up I can pick up my neighbors CB radio. Durning regular playing volume it is not a problem at all, the guitar is vastly louder than the "voice" coming from my amp. It seems to only occur when my hilton volume pedal is hooked up, but I haven't troubleshooted it enough to know for sure.

Physically speaking, what is going on? How is the circut picking this up?

and just in case: again, this is not a "problem" or a "flaw" in any way, I really have to crank the gain way louder than I ever would realistically need to in order to play steel. I'm just curious how it could be happening.

Edit: Its entirely possible the problem is outside of the hilton pedal, I should test more before claiming it is caused by a specific component.

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

Ben, thanks for using my pedal. I have lots of protection schemes built into the electronic design of the Hilton circuit. One of the protection schemes is radio frequency protection, protecting against radio frequency from entering the input of the pre-amp. I use a 39pf capacitor to ground on the input of the pre-amp. This means "any signal" in the radio frequency range is diverted to ground bacause of the 39pf capacitor to ground. This is the same radio protection scheme Peavey Musical Amplifiers use on their pre-amps. I can't explain why you are hearing the radio. The radio frequency is getting into the system other than the input of the Hilton pedal pre-amp, unless it is somehow translating to a lower frequency. The 39pf capacitor to ground will shunt any signal to ground in the radio frequency signal range.

Dave Grafe · From: Hudson River Valley NY

Is it a CB or Ham rig? A CB is by law severly limited in power but a ham rig could easily dirty the ground in any circuits nearby, which can be aggravated by any resistance in the building's grounding scheme.

One well-known music hall in Detroit converted all the outlets to the modern three-conductor grounded design in the early 1980's, but never connected the ground circuit to an actual grounded element, effectively installing in the walls a huge antenna, distributing the signal from several nearby commercial radio stations to any and all guitar amps and sound gear that plugged in there.

Bob Vantine · From: Freeville, New York, USA

During the late 70's/early 80's had that problem all the time with my Fenders & Ampegs. Never had any problems like that after switching to Peavey ... until last year at our church , one time only .

The inside of the church is entirely covered in fancy tin , walls & ceiling .I changed out my NV 112 with an EFX 112 {80w down to 65w} and have not noticed any further noise. Rolling Eyes

Always wondered about the antenna thing with all that tin . Oh Well

Also changed from a single coil to a hum-bucker guitar , didn't want to chance anything { Embarassed

you should've heard the topic coming from the radio signal Embarassed

}
_________________
EQUIPMENT:
"TEAK" ZUM STAGE-ONE Steel / C6th Lapsteel
Peavey NV112 , CLASSIC and EFX112 amps
Peavey Guitars

Papa Joe Pollick · From: Swanton, Ohio

Every wire in tour rig is an antenna that will pick up RF...Guitar and amp and every wire between them..They all need to be shielded and well grounded..
I solved the problem by sheilding the electronics in my guitar and then replacing all the input wires in my amp with sheilded wires..
Send those unwanted RF signals to ground..

Jack Stoner · From: Kansas City, MO

RFI can have many causes. A bad guitar cord (and the molded connector types are very bad as they are not fully shielded). Many places in an amp for RFI to get in including the reverb pan, the cables connecting the reverb pan to the amp, input circuitry, etc. Unshielded connections in the guitar (and every steel I've seen had an "open" output jack).

Finally, it may be getting in via the AC power line.

You have to take it one step at a time until you find where or what is causing it.

CB power is limited to 5 watts but that's enough to cause RFI in many situations.

Blake Hawkins · From: Florida

If the speech is clear, it is probably a CB because that is AM modulation and it can be easily converted from RF to sound by any transistor junction or grid circuit in a tube amp.
As Jack correctly pointed out, the output power of a legal CB is 4 or 5 watts. However, there are still
some "foot warmer", high power linear amps in use.
Also, as Jack noted, the signal can get into the
circuitry almost anywhere...it does not always come
in the input.
Should the signal be coming from a Ham Transmitter,
the sound would be distorted and garbled. That is
because the modulation is SSB (Single Side Band).
Also a Ham radio station will give a call letter
identification periodically.

Quentin Hickey · From: Nova Scotia, Canada

Dont automattically think that the Hilton pedal is faulty. A CB'er friend of mine runs so much power that the outside light on his house turns on every time he keys the mic up.
If the speech is clear than it is 100% one of youre neighbours
The voice coil in youre speaker is acting like an amtenna which is picking up a close by neighbours CB station. If he is splattering like that than he either
A- is a novice
B- doesnt care
C- Thinks he isnt cause RF splatter
2 solutions
Nice way- tell him(cb radio operator) who is probably running alot of power to run a low pass filter in line of his coax. This allows his frequency (27.????)mghz to pass through without second or third harmonics splattering all over the neighbourhood. Tell him to make sure that all of his station equipment is properly grounded. If he doesnt cooperate than tell him its against the law to runn more thatn 4 watts. THis is when he cooperates and gets a low pass filter, he is probably coming through computer and stereo speaker all over the block.
Mean way- Go out and find the CB antenna and at night sneak up and cut his coax( this will cause him to not get out) or put a pin in it, (this will cause him to run a high SWR).
I wouldnt suggest this way as it will give you some awful Karma.
I am a radio operator and I try to be considerate of my neighbours first and foremost. I always ask them if I am coming over anything in there house. So if this guy is a "good" CB'er than he will understand and cooperate.

Keith Hilton Pedals are awsome!!! I jsut got mine in the mail on Friday from Al Brisco.

Q

Dave Grafe · From: Hudson River Valley NY

Excellent information, Quentin!

Chuck Blake · From: West Virginia, USA

I'll jump in this. CB'ers in the day and today do not understand much radio theory. They usually jump in and buy a 5 watt radio, add a high gain antenna, a power mike and a linear power amp and then try to talk around the world. When they are unsucessful they dial up the "power mike" and turn on the linear.

All they accomplish by doing this is to modulate their signal out of band with and splatter it all over the spectrum. You as a neighbor get juiced up, out of band, modulation that rides on a little RF and seeks anything electrical with a speaker.

Ham radio is typically the cleanest, in band signal being generated.

I'm a ham radio operator, "one day my neighbor called and told me I was coming in on her Organ....whoa Whoa!

. Before I took credit for that dsatardly deed I invited her over, when she came in I asked her if it was still happening, she YES. I took her (with my wife along) into my radio room and showed her all of my equipment was OFF. I also told her and my wife verified my story that I had not used my radio all day. She left

embarassed and we remain friends today.

Bottom line, look to the "Gud Buddies" in your neighborhood (they're the CB'ers). Also enlist the aid of the hams in your area to help you discover who's generating signal.

MTCW Winking

Ben Feher · From: Austin TX

The speech is clear and I'm relatively confident that the problem is that there is some high power/gain transmitting involved since he was bragging about people being able to hear him and not some other guy. "Fire on the wire" was mentioned. I only get half the conversation obviously.

I'm not concerned enough with it to go forth and take action about it. He doesn't use it 24/7 and its low enough to not be an issue unless I totally crank the gain all the way up, which I wouldn't ever do if I'm playing.

I'm pretty confident that there is no fault with the hilton at all. I really like the pedal.

Tom Moore · From: Connecticut, USA

Try changing the length of your patch cord. It's a simple fix that may work. Whatever length you are using may be resonant with his transmit frequency.

A few mix43 torroid beads on your cords may "wipe" the problem away.

A common mode filter on your ac line may work if the interference is sneaking in that way.

It's a process of elimination kind of problem and can be frustrating.
Good luck.

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