[Yaesu] background noise

[John Hirth]

Yes Andy, there are devices to help reduce the effect of background
noise (within limits).

Two types of audio equipment that are designed specifically for this
purpose are called "noise gates" and "expanders" (or "downward
expanders"). These functions are often combined with other audio
processing functions such as equalization (boosting or cutting certain
audio frequencies relative to others) or compression, but are sometimes
found as single purpose devices. 

The way a noise gate generally functions is to cut off (open) the audio
path if the incoming level is below a user specified threshold and
connect (close) the path for louder audio. You set a threshold control
so that the audio path is open (off) when there is only background noise
present, but closes (connects through) immediately when you start to
speak into the microphone. 

Expanders are a bit different in that they simply reduce (not eliminate)
the the output audio level when the input level is below a threshold,
and allow it to pass unaffected when the level is above the threshold. 

Sometimes complaints of "lots of fan noise" are caused by having your
microphone gain set too high causing excessive levels of ALC in the
transmitter, which effectively reduces the level of louder audio while
seemingly raising the level of softer sounds (fans?). Adjusting mic gain
for ALC indications on loud voice peaks only will reduce the effect of
the fan noise.

Of course, if the incoming level of your background noise is very close
to the level of your voice at the microphone, no equipment (other than
perhaps software noise reduction DSP techniques) can materially change
that. In that case, you'll have to move the noise source (fans) farther
away from the microphone or perhaps put a partition of some type between
the noise and the microphone.

You'll find that most of the those hams who have hi-fidelity or
"broadcast" quality SSB audio on the air are using noise gates or
expanders as part of their audio processing chain. 

[No commercials, just for information: this audio gear (new and used) is
widely listed at the EBay auction site or available specifically for
hams (W2IHY).]

I hope this is useful.
73, John W2KI
--------------------

Andrea De Feo wrote:

Hello to all

I hope this message will be not a little bit off topic, but, probably
could be "interesting".

I have a barand new FT1000 Mark V and a MD100 microphone. This
microphone, unfortunately ,
gets a lot of background noise, I mean when a switch my home brew linear
amplifier on the noise of its fan probably, a little bit noisy, "enters"
in the microphone causing some troubles you can easily immagine.

So my question is is there any electronic circuit to " cut "  this noise
??

Is there anybody have my same problem and have already found the
solution.

Any suggestion will be appreciated.

73 and best DX
Andy I7DFV