Dr. Gerald N. Johnson writes...
> It would also be great to measure as much about the performance as
> possible (MDS, S/N, blocking range, audio bandwidths, gains everywhere)
> before and after the project to see if the benefit I expect is really
> there. And to write down perceptions, as some of the improvements may be
> subtle.
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).
Maybe it's the issue of the AF pot needing a higher series resistance,
or because an audio mod that had been done on mine was undone, as were
both suggested when I brought that issue up.
Also, when I turn off AGC, the audio problem gets much worse, though
this is a function of strong signals being received suddenly getting
loud.
But I'm also wondering if it's old, leaky caps. After restoring the
audio mod as we discussed, my plan is to work backwards in the audio
chain, replacing electrolytic caps as I go.
Rick, KR9D
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