On Wed, 2008-03-05 at 17:44 -0500, Joe Roberts wrote:
> 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.
You may like that added bandwidth out to 3 KHz audio but I prefer to
roll it off at about 2100 Hz with the DSP in my receiver. I find it copy
of voice signals is more comfortable with the narrower bandwidth.
Perhaps that comes from years of using a Collins with a 2.1 KHz filter
bandwidth.
>
> 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
>
73, Jerry, K0CQ
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