[Amps] 813's

[Fuqua, Bill L]

  Graphite is always messy, I have gotten it on hands clothes and it is hard to wash out.
I think perhaps they should not have earned such a reputation. I believe the problem stems from the
fact that most 813 amplifiers in the early days had untuned inputs and that they were pushed
harder than they should have been. Mind you these tubes in triode connection are about like 572B's.
They have even less plate dissipation than 572B's but I suspect the idea of pushing them to
2kW PEP plate input was just too much. Also, most used 813's I have gotten had very little
emission left. That is an indication that they were used beyond the point where if pushed to
get full gallon output they were probably producing a very dirty signal. I think if you use
a good pair, with tuned input and don't try to push them too hard they will be just fine. Treat them
as if they were a pair of 575B's. 
 73
Bill wa4lav

________________________________________
From: Amps [amps-bounces at contesting.com] on behalf of Tom Osborne [w7why at frontier.com]
Sent: Monday, December 21, 2015 1:57 PM
To: amps at contesting.com
Subject: [Amps] 813's

Why are 813 tubes considered 'dirty'?

I have an old amp in the attic I haven't used for a long time that has a
pair of 813's in it  I have read somewhere that they are a very 'dirty'
tube.  I'd assume that means lots of spurs or something.

Just wonder why that would be.  73
Tom W7WHY
_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps