[Hammarlund] Results on SP-600 project

[stbradford]

First off let me say I sure got my arm exercise with this 66 pound 
monster. Can't count the number of times I flipped the radio over and 
then back to right side up.

http://home.insightbb.com/~w9hak/index.htm        will show the outcome 
of the mica capacitor changes. Al Parker's dual trace scan of his bfo 
oscillator and bfo buffer plate is how my wave forms also look. It is 
safe to say that is just the way it's going to be with this Hammarlund 
receiver.

In investigating the avc lines I did find some small differences in the 
radio vs my schematic, no big deal there. The -51 volt line and the -10 
vdc lines were ok, so I didn't mess with the bathtub capacitors at this 
time. However I did find that the decoupling capacitor in the cathode of 
the avc detector to be leaking and pulling down that cathode bias. Some 
schematics don't show any decoupling, mine had a .01 mf ceramic 
installed at that location.

I made sure my 455 khz i.f. was centered on the crystal filter 
frequency, it turned out to be 455,016 hz, and the touched up the low 
i.f. tuning. The Idea was to be sure all the coils tuned correctly. They 
did, and 200 cps filter seems to be working correctly, nice and sharp, 
with the phasing control also working.


Smith Bradford
W9HAK