View Single Post
Old 4th Jan 2012, 12:16 pm   #6
amornummi
Triode
 
Join Date: Mar 2008
Location: Huddersfield, West Yorkshire, UK.
Posts: 45
Default Re: VMARS RA17 product detector modification

I tried the 6BE6 as bfo + product detector and didnt like it. Due to "lock in" and distortion.
I ended up putting a 12AT7 in , half as bfo, and the other as audio amp. Detection by diode bridge driven by 75+75 turns added on bfo coil.
The addition of a pnp emitter follower to drive the agc line (from 12 volts only) makes the ssb performance equal to any modern rx.
Also , get double the audio power out by using the "aux" op EF91 in parallel with the main o/p - 0.47 mf between anodes to keep extra dc from o/p tranny.
amornummi is offline