RadioBanter - Radio noise

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I have a boat at a marina,I cannot receive any AM radio using Marina
power.
The audio is one continuous buzz across the dial.
A battery operated radio is ok
FM reception is ok.
I took a scope down and looked at the A.C. waveform, the signal has no
visable noise riding on it, however the wave peaks are flatened. It is not
hard
clipped, it just doesn't have a nice round peaks.
I'm looking for suggestions on how to filter the AC so my
radio will pick up AM.

Thanks
Mike

Turn off your battery charger and I bet the noise goes away. :)

73
Gary K4FMX

On Fri, 13 Feb 2004 01:41:15 GMT, "amdx" wrote:

I have a boat at a marina,I cannot receive any AM radio using Marina
power.
The audio is one continuous buzz across the dial.
A battery operated radio is ok
FM reception is ok.
I took a scope down and looked at the A.C. waveform, the signal has no
visable noise riding on it, however the wave peaks are flatened. It is not
hard
clipped, it just doesn't have a nice round peaks.
I'm looking for suggestions on how to filter the AC so my
radio will pick up AM.

Thanks
Mike

I have a boat at a marina,I cannot receive any AM radio using Marina
power.
The audio is one continuous buzz across the dial.

I'll bet you have a 110V/12V charger/converter on board that's on whenever your
shore power is connected...

Good suggestions guys, but I don't have any battery chargers, batterys or
converters on the boat.
Just plain old 120v wiring.
I have walked the marina and the noise on my portable radio gets loud
when I hold the radio close to each power pedastal.

"amdx" wrote in message
...
I have a boat at a marina,I cannot receive any AM radio using Marina
power.
The audio is one continuous buzz across the dial.
A battery operated radio is ok
FM reception is ok.
I took a scope down and looked at the A.C. waveform, the signal has no
visable noise riding on it, however the wave peaks are flatened. It is not
hard
clipped, it just doesn't have a nice round peaks.
I'm looking for suggestions on how to filter the AC so my
radio will pick up AM.

Thanks
Mike

Good suggestions guys, but I don't have any battery chargers, batterys or
converters on the boat.
Just plain old 120v wiring.
I have walked the marina and the noise on my portable radio gets loud
when I hold the radio close to each power pedastal.

That sounds, then, as if "hash" from other peoples' battery chargers,
switching power supplies, and perhaps the dock lighting systems is
getting back into the power mains. Not terribly unusual.

Corcom, Delta, and other manufacturers make modular RFI/EMI filters
which you might be able to use. They're usually built into a sealed
metal can; they usually have three leads or push-on tabs for
connection to the incoming power (and ground) and a pair of leads or
tabs for the filtered AC power. I've bought them at local
electronics-surplus stores, hamfest fleamarkets, etc. for a few
dollars each.

One such is http://sales.goldmine-elec.com/prodinfo.asp?prodid=6379 -
a 10-amp LC-type line filter, which they normally sell for $5 and have
on sale for $2.95 (plus shipping of course).

You could wire this (or a similar one) up in a metal or plastic box,
with a line cord, a duplex outlet, and a circuit breaker or fuse, and
have yourself a pretty nice little line-noise-reduction device.

It might not be a bad idea to add some ferrite beads around the wires,
as well, to help attenuate the higher-frequency RF noise which might
be present.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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