[Heath] HeathKit SB-300

[Bob]

I recently restored a HeathKIt SB-300. The 15 and 10 meter front end 
coils were severely damaged. I was able to repair them using epoxy. The 
15 meter circuits now peaks when tuned and the crystal calibrator signal 
is an S-9, but I am still having issues with 10 meters. The coils peak 
but the crystal calibrator signal on 10 meters is on S-3 as best. I 
replaced the 68pf silver mica cap with a known good one. Also the peak 
across the four 10 meter segments occur at different positions on when 
peaking the preselector, as an example 28 MHz peaks with the capacitor 
almost fully closed, but the 28.5 peaks with the capacitor almost fully 
open. The 29 Mhz peaks mid range. Seems odd. I have seen where some are 
reporting that on 10 meters they get 20 dB over S-9 using the 
calibrator. Also if I leave the 15 meters ant coil peaked I get 
oscillation, so I have had to back it off slightly from peak. I suppose 
I could install a choke similar to the SB-301.

As background I have replaced all resistors, electrolytic caps and 
disc/silver mica that I found where open. There is no AC ripple and all 
other circuits are operating as designed. When operated on 80-15 the 
calibrator readings range from 3-20 dB over S9. Any thoughts very much 
appreciated. I tried to use SB-301 coils replace the damaged SB-300 
coils, but the 301 coils have different spacing requirements.

Any thoughts on resolving this issue would be appreciated. Also if you 
have an SB-300 parts unit I would like to get the coils.

73

Bob, W8RLC