[R-390] Re: Ballast Tubes/Motor Start Capacitor

[Michael Murphy]

Method 4: Actually, a non-polarized capacitor would run cooler to drop a few
Watts. I come up with 100 uF - 120 uF. Somebody check my math. This mod
should confuse the ballastless b*^*$%ds who have to inherit our R390A's.

Method 5: The resistance linecord idea. For extra credit calculate how many
inches are required for 50 Ohms. Wrap this solenoid style around the
existing tube to form a common mode choke to reduce interference from BPL
which I figure, must be getting into the VFO fillaments.

Happy 4th all!

Mike WB2UID

----- Original Message -----
From: "Tom Norris" <r390a at bellsouth.net>
To: <R-390 at mailman.qth.net>
Sent: Sunday, July 04, 2004 3:51 PM
Subject: [R-390] Re: Ballast Tubes/transmitting receivers/Dogs and Cats
sleeping together...


> I suppose the common 12BY7 ballast replacement could by used
> in a simple MOPA circuit, or maybe crystal controlled like a Tuna
> Tin transmitter...
>
> Hmmm
>
>
>
> >Has anybody ever investigated the possibility of switching the 3TF7 out
with
> >a triode-pentode that could do double duty as a ballast and a
transmitter?
> >Seems like an R-390A/URT Transceiver could be a possiblilty. Heck, you
> >already have a T/R relay built in, all the power supplies you need, and
> >crystal oscillators. Probably too much to ask for plate modulation, but
for
> >CW it might be a great rig, if a bit on the overdesigned side on the
> >receiver part.
> >Jerry W5KP
> >
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