[Kenwood] How to reduce the TS850 "hiss"?

Sun, 9 Jun 2002 00:44:40 +0200

Hello from Italy,
 I'm very satisfied of my TS850S that I bought used two years ago and I
believe that it is still the best bargain radio on the used market.
After some mods like separate RX antenna using the DSP connectors (no extra
holes...) and the NB without the capacitors (good improvement) and after
adding a RS232C interface
(http://www.hamlan.org/tech/kenwood232/knw232.htm), now I'm searching some
other mods to improve this great radio.
One thing to improve is the "hiss" in the receiver: the 850 receive very
well, but the RF/IF and audio "hiss" are very annoying...
My next mod will be the substitution of the audio PA with a TDA2003 IC: this
is a lower noise IC pin to pin compatible with the original uPC2002
(TDA2002) and I think that this will reduce a lot the audio "hiss".
The most important goal would be the reduction of the RF/IF "hiss" but it is
a hard task to find which stages are the noisy ones in the RF/IF chain...
Has anyone already done this job and discovered a solution?
In my radio (and also another one), I found that excluding the preamps with
AIP button reduces a lot the noise, do you think that it would be useful the
substitution of the original preamps (mosfet for 10m and parallel of fets
for the other bands) with some kind of low noise and high dynamic range
preamps?
Thanks, best 73 and ciao
Guido, ik2bcp / ab9dg