[ARC5] Some info on the S-38

[Kenneth G. Gordon]

According to a service bulletin on the first model S-38 I just found, the 
sensitivity was:

12 microvolts at 600 kc
12 microvolts at 5 mc
11 microvolts at 14 mc
23 microvolts at 30 mc

for 50 milliwatts output.

Also, the BFO injection in the first S-38 was to the detector, while it was 
injected into the IF stage in the S-41G.

Selectivity for the single IF stage for the S-38 was:

7 kc wide at 6 dB down
65 kc wide at 60 dB down

>From what I can see, the mechanical and electrical layout of the S-38 was 
identical with that of the earlier S-41. The tube string was identical.

I like Bob Fuqua's idea of replacing the 12SQ7 with a product detector, but I 
think I would use a 12SL7 dual-triode instead. Using 1/2 for the BFO and 1/2 
for a triode-product detector, the reason being that with the 
triode-product-detector, it acts like a plate detector with the BFO turned off 
and thus does a good job of demodulating AM.

Ken W7EKB