I notice something about my Corsiar II. There is quite a bit of background
hiss and noise on RX. With the RF gain reduced to 0, the AF stage first
becomes noisy when the AF gain is set to 3. It becomes fairly loud at 5.
With AF set to 3, I first hear the noise floor rise when the RF gain
control hits 4.5 and it becomes noisy at anything over 5.
The noise is not affected by the attenuator and is only partly affected by
the Xtal filters. It is definitely reduced by the variable audio filter.
If a signal is very strong, the AGC will reduce the gain and I get a nice
quiet background under the signal (high S/N ratio). If signals aren't that
strong (below S-8 or so) the AGC doesn't reduce RF gain enough to quiet the
background and signals are somewhat down in the mud (hiss as it were). I
can still copy them but the reduced S/N ratio makes it tougher.
Is this the way the rig works or does mine have a problem? Other than this
noise the rig works fine. Maybe I'm just too used to high end audio gear
with S/N ratios over 90 dB..
Keith Darwin
KD1E
Ferrisburg, VT
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