[AMRadio] Ferroresonant transformer revisited

W7QHO at aol.com W7QHO at aol.com
Wed May 10 23:01:21 EDT 2006

In a message dated 5/10/06 7:26:42 PM, k4kyv at hotmail.com writes:

> I use a T-368 PTO as my main station vfo.  I stabilised it by  running the
> filaments off a regulated DC supply.  Also use it to run mic preamp.  Now
> have stable VFO and hum-free microphone preamp.  I'm not sure why a small
> fraction of a percentage variation in filament voltage will cause such
> noticeable drift.  Without the regulated filament voltage, neither the A4
> nor the T-368 pto are stable enough to work 40m cw using a narrow filter.

T-368's following the "Basic" model included a constant voltage xformer for 
the PTO filaments.

Dennis D. W7QHO
Glendale, CA

More information about the AMRadio mailing list

This page last updated 16 Dec 2017.