[R-390] RF Deck B+ short (390A)

[Grayson Evans]

A little more info for you.
My RF deck is on the bench, tubes out, everything disconnected including the coils
I measure 125K from pin A to ground.  This high value is probably due to the coils being unplugged.
It is very hard (for me) to trace the B+ line under all that circuitry, so it might be hard to disconnect someplace convenient.

Notice that L209, the RF choke that is attached to pin A is 25 ohms, so your short is really 60-25 or 35 ohms.

With the tubes removed, try measuring from the tube plate pins on the sockets to ground and see if you see anything weird.  

You got me interested, so let me/us know what you find.

Grayson


Grayson
TA2ZGE - Ankara, Turkey
KJ7UM
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