[Swan] tube testing

[w7lrd at comcast.net]

Hello (again)
I'd like to bounce this info off a few of you who responded to my prior emails about testing PA tubes. I have about three dozen 6LQ6/6JE6/6MJ6 PA tubes that I have been collecting over the years and didn't realize I had such a stash.  I used my favorite 350C, disconnected the B+ from one of the PA's, used the same socket for testing,  All I adjusted was to peak the PA plate and PA grid for each tube.  I recorded the power output as read on a Swan WM-3000.  This may or not be accurate, all I wanted was a relative indication for comparison.  I also recorded the Ip for each tube.  This way I can pair up a couple of tubes that are fairly close in capability. Prior to evaluating I neutralized the PA with one tube conducting.  One of the tubes took off like the 4th of July inside, lots of pretty arcs and sparking going on,  I really flew out of the chair.  Now, be weak or not I have some fairly closely matched PA's.  A couple of good ones will load up to over 550 MA and according the the
 WM-3000 and are putting out over 300 watts.  This was done on 20 meteres, obviously the output will be lower on 10 & 15.   About 10 went right to the trash, zero or less that 5 watts output.  I will be doing the same thing with some 6LB6's which are a 6 volt version of the 8950, in one of my 700Cx'.  Your comments and or observations please.

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73 Bob W7LRD 
AMSAT member 28498 
Seattle