In article .com,
"MojaveDxer" wrote:

Telamon wrote:
In article .com,
"MojaveDxer" wrote:

I am getting a horrible buz across the bands that is coming from
my neighbors apartment. Would one of those ANC-4 or the MFJ unit
get rid of it.

Periodic noise, that's noise spaced every few kilohertz is probably
a TV, maybe a plasma TV.


It's a constant buzz from the bottom of the BCB to 40 meters. I get
the same buzz when the dimmer on my halogen lamp is being used. Its
so strong that my loop antenna wont null it out.

Buzzing noises that are louder at lower frequencies are indicative of
switching pulse noise. These square pulses are rich in higher harmonic
frequencies. The power of these harmonics drops off the higher in
frequency you go.

Switching power supplies, gas vapor lights starting up, light dimmers,
and other items generate low frequency pulse currents.

Another thing happens in the receiver itself. When you hit the front
end of a radio with these large low frequency pulses it generates very
broad spectrum intermodulation products that desensitize the front end
of the radio by raising the noise floor across the bands and also
affecting the AGC so even when you are not tuned to a harmonic of the
pulse noise it adversely affects your reception.

One way you can improve reception in a noisy location is to use a high
pass filter with a corner frequency of a few hundred kilohertz.

You can see that low frequency pulse switching noise has several
adverse affects on radio reception.

I have no experience using the ANC-4 of MFJ noise canceling units.

--
Telamon
Ventura, California