[Elecraft] KNB2 does not work on my power line noise

[Ron D'Eau Claire]

I'm not sure about the circuit in your Kenwood, but one form of noise
reduction that I've missed on more modern rigs is a "hard limiter". =
That's a
circuit that strictly limits the maximum amplitude of the audio to a  =
set
level. Noise peaks, which tend to be very much stronger than the signal, =
are
"clipped off" at the same level as the signal.=20

It produces some distortion in phone signals, but the distortion in =
minor in
CW, and even phone signals are much easier to hear than without it.

It's not as good as a noise blanker, like the K2 has, for high-impulse
noise. The blanker literally punches a hole in the signal where the =
noise
pulse was so there's no noise left at all. There's little distortion =
caused
by the holes, but that's all - when it works - and the distortion is =
very
minor.=20

But a blanker only works on noise that it can identify, measure and =
punch
the hole in the signal at exactly the right instants. If the blanker =
can't
do that, it doesn't work.

A hard limiter keeps ANYTHING from exceeding the limit level. QRN =
crashes,
pulse noise, anything. So while the noise is still there, the
signal-to-noise ratio is greatly improved on ANY kind of 'noise' - even =
a
very strong signal nearby that is still in the passband.=20

Ron AC7AC



-----Original Message-----
...the more complex circuit found on my ancient Kenwood TS-50S does =
wonders
reducing that same power line noise.

73,
Mike / KK5F