Many years ago, just before Drake stopped accepting TR-4 s for repair, my
neighbor, WA5VGO sent his TR-4 to Drake for some repair. The radio came
back with three different final tubes then when shipped to Drake. One of
the three new tubes was as you described. A sweep tube with a printed
circuit on the bottom changing the pin out of the tube. I don't know if it
was a 6JM6 or not. However, the tube was put in there by Drake. Also, the
three new tubes were taller then original and Drake had dimpled the top tube
cage cover to accommodate the extra height of the new tubes. Strange
indeed, but the radio worked just fine with these tubes.
Lee, w0vt
Hello!
Just to complicate a bit more this subject ;-), some years ago I worked on
a
TR-4C which had 6JM6 tubes on it. You can read about that here:
http://jvgavila.com/dktr4c_1.htm
They had a professional-looking adaptor on their bases but, definitely,
worked.
And were labeled as 6JB6A!
So it seems that, with some imagination, you can get a Drake transmitter
working
with slightly different tubes. Of course, I would stick with 6JB6 while
they
last.
Regards,
JOSE
--
73 EB5AGV - JOSE V. GAVILA - IM99sm La Canyada - Valencia(SPAIN)
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