On Sat, 17 Feb 2007 22:26:50 -0600, "Pete KE9OA"
wrote in
:

....... about the receiver desensing.....I don't have any
problems with IMD in the receiver......


IMD is minor compared to the negative effects of high input impedance
of the RF preamp, which is almost always too high. Reducing the 1st RF
gain (A = 5 to 10) will reduce the input impedance and make it less
vulnerable to noise -- especially the white background noise. You can
compensate by increasing gain in the IF stages. Then realign your
input matching network and =blammo=, weak signals are solid with
much less noise.


......., and a diode attenuator is used in the
front end. I have found that IMD performance can be improved by changing
that general purpose switching diode in the front to a 1N5767 PIN diode.


As long as the original isn't used for overload protection, I don't
see any problem with that. But then I don't see any advantage, either.
The band is just too noisy for it to make any significant improvement.
Still, I've got a crusty old Diamond 60 laying around somewhere, so
I'll give it a try anyway.