That's very true Bret. I got an idea about 20 years ago from RCA
and Gates BC XMTRS diagrams. They use direct coupled cathode followers
to drive the grids of the 833s. Not a lot of trouble considering the HV
transistors that we have today. The FETs and bipolar transistors have
better characteristics for that sort of thing than the 807s they used
back then. I would never go to a class B or AB2 grids with out my
transistor drivers.
See http://www.qsl.net/wa5bxo/driver1.html
I have always wanted to try the inverse feed back circuits that
RCA and Gates used on the modulators. But I never have. I once had the
schematic diagram of the Gates 1KW but lost it in the flood of 94. I'm
sure there are a lot of ways to do it I just have never taken the time
to try.
BTW I think your right. I have learned a lot more from stuff
that didn't work out quite right.
I think the most time consuming thing I ever did was to
neutralize a single triode using an inductor from plate to grid (in
series with a blocking cap of course. The inductor resonates with the G
- P capacitance of the tube. Let me say "It Works very well, but it is
not my first choice for construction mechanics, plus it has to be tuned
every time you change frequency.)
73,
John, WA5BXO
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Brett Gazdzinski
Sent: Sunday, November 30, 2003 9:41 PM
To: [email protected]
Subject: RE: [AMRadio] Re: Modulation transformer ID and repair
The push pull parallel 100TH deck does take quite a bit of
driving power, with the losses, likely close to 20 watts,
which is what the UTC LS grid transformer is good for.
That may be part of the problem, but class B triodes always
seem to sound less clean than a good AB1 amp.
Brett
N2DTS
