[1000mp] CW Cap Mod and I.F. Mod not the Same - Over and Out

[WD8ARZ]

I.F. hiss due to insufficient previous stage gain to over come the internal
noise of the next stage, and audio high frequency response pass band at
audio frequencies (cw or other wise) are two different topics..... and two
different and unrelated mods.

If the I.F. noise issue was being cured as you say by the cap mod in the
audio circuit, why aren't the other audio paths that feed Ssb for example,
also being modified to reduce the 'i.f. hiss'????

The cap mod for the cw audio stage frequency response high end roll off is
just that and nothing more. It doesn't reduce the I.F. stage noise one iota
.... only affects the audio frequency response.

Too many folks here are using the term 'hiss' as a single source item, and
it is not. Band noise 'hiss', rf amp noise 'hiss', i.f. noise 'hiss', diode
noise 'hiss', mixer noise 'hiss', audio frequency response 'hiss', etc etc
are not the same and have to be treated individually. Noise that is passed
from one stage to another can accumulate, but only if it is in frequency
range of the stages that pass them and handle them, or the harmonics and
distortion products inter relate. The audio stages do not handle i.f.
frequencies.

Put a noise analyzer in the I.F. stages, and put the CW cap mod in and out
of the cw audio stage, and you will see ZERO effect in the I.F. stages.
Period!

You cant fix the effects of the I.F. at audio frequencies. You can mask the
effects of noise at the audio side, but that doesn't take care of the i.f.
side. Signal to noise ratios, noise blanker performance, and dsp functions
are all affected by what comes to it from the earlier i.f. stages, and are
improved by the Inrad modifications. Not by the cap mod.

This is also not a situation of agreeing with me or not on the CW cap mod.
As I have said before. It is a user choice and I have made my choice and you
should make yours. The technical side of it has nothing to do with the
agreeing with X Y or Z persons, so your best to leave the emotional side out
of it. Confusing sources of hiss, and mixing circuit effects is not helping
the situation either .....

End of topic from me on this side. It is just a shame to see so many
misleading statements put out, that are technically dis connected.

73 from Bill - WD8ARZ
wd8arz@ix.netcom.com