[TMC] FRR receivers and testing 4CX tubes

[WA5CAB at cs.com]

Hal,

Unfortunately it was written too early to show the tubes you mentioned in 
your original.  But GE Ham News, May-June 1951, had a piece on Transmitter Tube 
Testing.  Possibly it could be adapted if you can figure out the correct 
numbers.  The GE piece covers only tubes that GE was making at that time 
(naturally).  They ran from 2E26 up to 4-250A, 35T, 100TH, 211, 203A and 592.  And 805 
through 838 plus 8000 and 8005.

In a message dated 12/18/2007 7:38:10 AM Central Standard Time, 
sdaitch at mor.ibb.gov writes: 
> >Hi Roy, K1LKY:
> >
> >Many thanks for your reply. This issue still bugs me.  I have several 
> >old ceramic tubes of unknown condition, and it would be a big hassle 
> >to open up my heavy, rack-mounted amplifier, remove working output 
> >tubes, replace them with the ones to be tested, and then stand back, 
> >cross my fingers, and hope no sparks fly!! There has to be an easier 
> >way for a quick, simple test before the REAL test.
> >
> >I guess my first question is: were any of the 1960s tube 
> >testers--military or commercial--equipped with the proper socket and 
> >parameters for testing these tubes? If so, which models?
> >
> >If not, I still feel it should be possible to make crude checks and 
> >comparisons of tubes for matching purposes.  An outboard socket could 
> >be wired to an external filament transformer that can deliver 6.0V at 
> >2.6A. The grid/plate/cathode/screen leads would be plugged into the 
> >tester's regular octal socket and its parameters set up for the 
> >closest matching standard tube, (6146?) just to get some kind of 
> >reading. Once a reading is established for a known good tube, that 
> >reading can serve as a benchmark for unknown tubes.
> >
> >It has been suggested that to save the bother of an external filament 
> >transformer, why not simply use the 5.0V setting or use a variac on 
> >the tester to reduce its 6.3V setting to 6.0V?  I am reluctant to do 
> >either because the 2.6A filament draw may damage the tester's 
> >multi-tap power transformer.  I would hope that for a brief test, the 
> >plate and screen draw will not damage the tester.
> >
> >What do you think?  Which standard tube listed in most tube testers 
> >best matches a 4CX250? I am surprised that no one has ever published 
> >in an older QST or CQ or "Hints &Kinks" a "workaround" means of 
> >testing ceramic tubes such as the 4CX250.
> >
> >Happy holidays to all TMC fans.  And a special thanks to John Poulton, 
> >K4OZY, for maintaining and expanding his invaluable TMC reference 
> >website to include the SBT-1K.
> >73, Hal
> 

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