Yes I agree, but not all up-conversion radios suffer from this problem. It
is a great pity that the design of amateur up-conversion radios do not seem
to include very strong IF amplifiers IIP3 in the +45dbm region, which allows
for some relaxation in roofing filter requirements , cost I suspect. Far
fewer close in spurious responses to deal with.
Geoff
GM4ESD
Bill W5WVO <[EMAIL PROTECTED]> wrote:
Well... yeah,sure. That's why the K3 offers a selection of appropriately
narrow roofing filters at the 1st IF frequency. If you're trying to copy
CW with the 6 kHz AM filter inline, of course you're going to have
problems, just as you certainly do with all the up-conversion radios (like
the TS-2000 I own) with broad-as-a-barn-door roofing filters in the 1st
IF. Strong off-frequency signals within that wide passband will cause
later stages to fall apart, no question. That's why the K3 (and a few
other radios like the Orions) are designed the way they are -- to do
everything possible to mitigate against that possibility.
Bill / W5WVO
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