[Amps] testing 572 B tubes

[Karl-Arne Markström]

In "Ham Radio Magazine"April 1978 there was an article titled  "Testing Power Tubes"
by Joe Carr K4IPV (SK). It covered the basics in transmitting tube testing and evaluation.
Recommended reading.

73/

Karl-Arne
SM0AOM

----- Original Message ----- 
From: <alan.kaul at att.net>
To: <amps at contesting.com>
Sent: Saturday, March 04, 2006 11:33 AM
Subject: [Amps] testing 572 B tubes


> Does anyone know if there is a way to test 572 B's?
> 
> I recently acquired this AMP.  It had "fairly new tubes" -- according to the previous
> owner perhaps 20-30 hours on them.  I found I was unable to load it up to more than 400-600W
> output and suspected the 500 pf plate bypass cap (which a couple of you mentioned as a possible
> problem).  I replaced the plate bypass cap, with a .001 mfd and added a .01 mfd in parallel.
> Then I replaced the plate RF choke with  a new choke from RF parts designed for use in
> Ameritron and other amps (it specs at 1.5A, 225 uH, 4 KV max).  Then I put it all back
> together and fired it up and the power output is pretty much the same as before I
> made the changes.
> 
> So I am wondering if the TUBES might be a little soft. 
> 
> Anyone  have any other ideas??
> 
> Please and thanks and best 73 de alan
> 
> --
> Alan Kaul W6RCL LaCanada, CA 91011
> e-mail:  w6rcl at amsat.org
> http://
> home.att.net/~alan.kaul/index.html
> 
> 
> 
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