RE: [TCML] help with biasing a tetrode for VTTC

["Richard Schmuke" <rdj@xxxxxxxxxxxx>]

The 4-400 makes a good triode , hook it up the same way you would a 3-500.
Hams often replace a amplifier that runs 3-500 with a 4-400. The pins are
all grounded. The tube can be cooled with a muffin fan if you make sure the
base gets a lot of air, if it is run 27/7 at CCS you need to run air thru
the base. You can use side flow with a Johnston ceramic base but it you use
a Eimac Sk406 base you need to have air flowing up from the bottom because
the Eimac base will shield the side of the pins and without up flow you can
melt the solder in the pins. Please don?t misunderstand the Eimac is a
better base but had different requirements 
Rich , Kd0zz

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Rick
Sent: Tuesday, December 28, 2010 8:41 PM
To: tesla@xxxxxxxxxx
Subject: [TCML] help with biasing a tetrode for VTTC

I've been studying the websites of Steve Ward and John Freau in an effort to
put together a VTTC.  The vacuum tubes I have on hand now are tetrodes
(4-400A style), and I am not clear on what I need to be doing to bias the
screen, and/or grid.  Perhaps I would have been better off starting out with
some triode tubes...
 
If I connect two such tubes in parallel, will I be alright with one filament
transformer matching the electrical specs for the particular tube, or does
each tube require its own plate transformer and a different connection
scheme?  Pardon my ignorance on the subject.
 
I note that these tubes were intended to be used with an air-cooled socket. 
Any ideas out there on cooling the tubes?  Would a muffin fan be sufficient,
or do I need a more directed airflow up from the base of the tube?
 
Any advice is greatly appreciated.
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