[Milsurplus] "Chirpy, Chirpy, Chirp-Chirp-EEE-Chirp!"

[David Stinson]

In my experience, Master Oscillator chirp
which does not involve faulty components
is most often due to lax MO voltage regulation.

I have a nice WWII Australian AT5/AR8 set, which several of
our fine and generous members from those beautiful southern
lands helped me get on the air.  I powered the refurbed set
with a Hallicrafters DC supply, primary 12 VDC.
Keying was... interesting.  The chirp was so pronounced,
I was worried the FCC might cite me for playing music.

I built a simple MOSFET source-follower regulator for
the low B+, fixing it at IIRC, 200V.  Keying became excellent,
with no discernable chirp.  I have applied this solution to
other MOPA rigs with equal success.  I don't often need
to do so because I run most of my rigs on the original
dynamotors and, through the rotor's inertia, they provide
good regulation for most loads.

I really need to get that lovely AT5/AR8 out of storage
and get it back on the air.

GL OM ES 73 DE Dave AB5S


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