There is WAY WAY too much AF gain in the Omni V. A factory recommended
fix was posted on this board recently by Don K6RV on 16 Feb 08.
There is also some overdrive of the product detector going on. W3TS mods
address that issue. Big help with IF noise and resulting AF intermod.
While re-capping your rig, try Increasing the SSB AGC time constant caps
to avoid pumping. I did this before recapping the rest of the board
and noted an increase in definition and clarity, as well as less jumpy
AGC, but I think the quality enhancement was a fresh spunky cap at work
rather than the change of value.
There are a number of overlapping issues with the Omni V that all impact
listening enjoyment. AF gain distribution is one, but excessive
digital noise which can be fixed by good caps and the above-mentioned IF
gain issue are others.
Replacing the stock 1st IF sideband filter with the 2.7 INRAD is also a
fabulous improvement which goes beyond mere bandwidth considerations. I
have never seem this adequately explained, but the ears don't lie (and
even if they do, how can you tell?). Others have commented on this
effect, so it is not just me.
All I can say is that it is extremely worthwhile to "retread" the good
old Omni V. With the fixes, it sounds as good as anything I've ever
heard...and I have always been a obnoxious snob about good RX audio.
Of course, the basic performance is outstanding too...and with the mods
you can finally enjoy it.
73 Joe N5KAT
I'm hoping that doing so will address an audio quality issue that I
have on my V. When I turn the AF knob past about 8 or 9 o'clock, the
audio amplifier clips, as we've discussed before. Using a clean
external headphone amp to equalize normalize the amplitude, I've been
able to observe that clipping on my scope. I can turn it way down, and
turn the external amp up, and there is no clipping, though the audio
noise floor rises, too (usually to no ill effect because of band
noise).
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