[ARC5] Strange problem with racked transmitters

[Dennis DuVall]

Not that much to one of these things.  As someone else mentioned a heater-cathode short in one (or both) 1625s could give the symptoms described but swapping-in new tubes didn’t fix the problem.
With the “bad” set turned off check the resistance pin 5 on either of the 1625 tube sockets to ground.  Should be 51K. (51,000) ohms.  If something lower and K-53 is indeed “open" look for shorts in the wiring, especially 
around the 1625 sockets the solder terminals on K-53.  Also, check for “improvements” made by previous owners.

For loading into 50 ohms, use a 100pf xmitting mica in series with the antenna terminal, peak output with the inductor and finally set the output to the desired value with the loading (variable link) control.
Been doing it very successfully this way since the 1950’s.  Never understood the fascination with un-uns and the like…..

The blue glow you are  seeing is probably due to electron bombardment of the glass tube envelope(s), not gas, and is harmless.

Dennis D.  W7QHO
Glendale, CA

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