Topband: Re: eliminating radio hum/hiss

[Sinisa Hristov]

Martin wrote:

> But wouldnt it be much better to eliminate the hiss by modifiyng the
> audio-amp of the TS-850 ( or any other radio) itself, or,
> if the audio-amp just amplifies the hiss that is
> produced somewhere else, to prevent the hiss from being fed into the
> audio-amp?

Well, manufacturers frequently produce "quiet" receivers
by filtering out most of [noise AND signal] energy above ~1 kHz.
Typical cutoff starts at 1 kHz with ~15 dB attenuation at 2.7 kHz.
This removes most of the noise, but unfortunately removes
most of higher speech frequencies.

You may wish to try higher-order [~8] low-pass filtering.
That would preserve most of the speech,
while removing unwanted part of spectrum.

Maxim has some easy-to-use IC filters.


73,

Sinisa  YT1NT, VA3TTN