Curt, your 20m success is
Got the Sprite finished an did some evaluation.
First, I've installed SIP pins for the filter parts and using the 2.5 mHz
version.
I attempted to use an FT23-43 core for the 6.2uH inductor.? I knew
that 43 mix usually didn't work well in resonant circuits, and it
didn't.
Using a Z-Match tuner, power output at 12.2V supply, to a dummy load was
100 mW.? I wound a different 6.2uH inductor on a T30-2 core and
getting about 500mW.
Connected the tuner to the Butternut antenna and getting the same
500mW.? Called CQ for a while but no RBN hits. With the straight
keyI'm using my station receiver for a sidetone.? Think I'll use a
keyer with sidetone as it simplifies things... ;-)
About noise.? Seems to be about as expected with a vertical
antenna.? I did hear a few weak signals but no replies to CQ so
far.
I happened to touch the top of the 10uF capacitor between pins 1 and 8 of
the LM386.? The noise went down markedly.
Does that mean that it was actually a noise reduction or did it
change/reduce the amp gain? And how would one implement a metal probe,
held in a hand, and touching the metal can of the cap... ;-)
Also tried a 0.001 cap from pins 1 and 8 to ground but nada...
Fun Stuff...
BTW, again, using SIP pins, I've assembled a filter test fixture from an
old Sprite board.? Plan to use the NanoVNA to do some measurements.
Chuck, W5USJ (ex K2OFN)
ARCI 5422, SKCC 19956
EM22cv, Rains Co., Texas
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Chuck, W5USJ
