[AMRadio] 807's triode connection question...

[John E. Coleman]

That's very interesting Bacon, I had never done any experimenting at low
level on this circuit before, and to be honest I can't see how the
current could go down unless there is a small average bias change at the
grid caused by the 20K resistor, but with out any capacitance in the
circuit where or how would it develop.  The control grid would of course
draw current through the 20 K resistor and there would be a voltage drop
across the resistor but the drop would not be stored without
capacitance.

I'm sorry I tend to get wound up in the minutia.
I find the reason for the problem to be more interesting that the fix
for it. HIHI

BTW Bacon
I'm not ever sure on these messages as to which are the latest it think
some times I receive them out of order.  Perhaps you should sent me the
finished copy of your last AM power/PEP write up once more with a date
and time on the top of the page HIHI.  You can send it directly to me if
you think the folks on the list or tired of seeing it.  "just kidding
HIHI" Send it how ever you like.


I love this stuff:
John, WA5BXO


-----Original Message-----
From: amradio-admin at mailman.qth.net
[mailto:amradio-admin at mailman.qth.net] On Behalf Of Bob Bruhns
Sent: Thursday, July 04, 2002 8:39 AM
To: amradio at mailman.qth.net
Subject: [AMRadio] 807's triode connection question...

Hi Vince,

I have never tried these connections, but HLR-Timtron told
me the RCA trick with drive to the screens and a 20K from
the screens to the control grids was not ideal, and several
experimenters tell me there's no way you get 120 watts from
it at 750V.

Tim said that when you bias this arrangement and drive it,
first the plate current goes down at low audio levels, and
then it rises at higher audio levels, and he didn't like
that.  I forget whether he said there was distortion, but I
think he would have overlooked the odd plate current effect
if it sounded OK.