[Amps] Type 813 BP Pentode

[Karl-Arne Markström]

For some ideas, take a look at:

http://stevepage.netfirms.com/813_amplifier_2.htm

or

http://w7iuv.com/813.htm

I sometimes run myself  4 x 813 in parallel (Va 2,8 kV, Ia 900 mA on the peaks), usually driven by
a KWM-2 or a KW Viceroy, which is quite well behaved up to 14 - 15 MHz approximately. 

Over this frequency the high output capacitance of the parallel tubes begin to show 
on the efficiency of the amplifier.

73/

Karl-Arne
SM0AOM
----- Original Message ----- 
From: "Harold B. Mandel" <ka1xo at juno.com>
To: <amps at contesting.com>
Sent: Sunday, May 08, 2005 2:49 PM
Subject: [Amps] Type 813 BP Pentode


> Gentlemen,
> 
> Someone asked me to put together a quote for building them
> a four tube type 813 amplifier, and I wonder if any of you
> could direct me to a source of practical schematics so I
> don't reinvent the wheel, please?
> 
> The 813 was real hot just before the second World War,
> but its poor VHF performance led to its unpopularity.
> 
> I have a source of tubes, sockets and spares, but I'd rather
> try a parallel configuration, but who knows?
> 
> Thanks for your reply. Oh, by the way,
> "101 Easy Ham Radio Projects" has one copy
> left, stained, for $55.00 plus shipping. (I dunno).
> 
> Hal Mandel
> W4HBM
> _______________________________________________
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> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
> 
> 
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