[Drake] T4XB tubes

[ed brooks]

Since I really had nothing particular to do today, I decided to pull the 
T4XB and see what tube, (if any) was the problem.  A quick voltage check 
showed me it was not, but not before I had swapped out the driver.  So I 
swapped that back.  (Took the one out of my TS520, which was known 
good.)   Anyway, pulled the final cage and measured VDC at the rf 
choke.  Tuned up with the maximum of about 30 watts output it read 430. 

Ah, ha, power supply problem!   Opened up the AC4.  Capacitor C1 (the 
above-ground one, of course!) is open.  I had hoped it was a diode, but 
no such luck.  Disconnected HV from the transmitter entirely, at the 
under-supply terminal strip, and checked the output of the voltage 
doubler.  459 VDC, with no load, drops to 380 or so under light load, 
just a little over half the 650 it should be.   

So will be scrounging from my surplus shops a replacement cap.  While I 
have it apart, checked all four diodes, the equalizing resistors (150K) 
and the transformer, as well as C2.  All OK.  If anyone has an idea 
where to finda "perfect fit" cap online, info appreciated.   If not, 
I'll install something different with an insulated mounting, maybe even 
a radial lead above chassis.   I have already had one of the LV caps 
fail and repaired that, about a year ago.  That was easy since only one 
section of a two section cap was being used.  Simply moved the line to 
the previously unused section and voila!   But one day that will 
probably go, too.

I have a couple of really good surplus stores in Albuquerque so may find 
one in there, but not too confident.

Ed, WHTW
And Happy New Year.  Started off good here - not only is the T4XB off 
line, but my weather station has quit working (at least quit input to 
the computer) and my coffee maker started leaking.  Decided I'd better 
check the tires on the car, the way things are going, but so far they 
are OK!