[HBR] Thanks for Synchronous Detector information

[Stan Wilson]

Thanks to all who respond with information on the Synchronous Detector.

Anyone interested in experimenting with one using glowbugs should start
with the CQ June 1957 article.

It uses 8 glowbugs.  However, if you want to modernize the circuit
slightly it should be possible to eliminate the reactance tube and
replace with a varicap.  Also two of the tubes are required for the
audio phase shift network and that is not required if you just desire AM
demodulation but would be necessary for SSB.

The I and Q demodulator are just detectors (mixers).   I think they
could be replaced with a Pullen mixers. 

One tube is required for the AGC stage.  

I am going to punch a chassis for all eight tubes plus power supply.
And will wire it up in stages.  I think I will also make provisions for
an audio output stage.   That way I will have a stand alone audio stage
for experimenting with various receivers.   One could also modify the
unit for other than 455 khz since only one tuned circuit is required for
the VCO.

Synchronous Detectors and Phase Lock Loops all sound scary for a glow
bug design, but once one exams the circuits they are basically just
audio amplifiers.   

Will let you know the results

Stan ak0b