[R-390] R-390 BALLEST/HELP

[Jim Miller]

One popular mod. is to substitute a 12BH7 tube in the ballast tube socket, 
with jumpers at pins 2-4 and 5-7 of that socket.  The 12BH7 filament 
provides the voltage drop.   The mod is simple and easily reversable, and 
you won't miss the 3TF7.  By the way, you can still use a 3TF7 if you want 
to in place of the 12BH7.

Here's an old thread on ballast tube and replacements: 
http://209.35.120.129/Pearls/ballast-tube.pdf

.


----- Original Message ----- 
From: "CLARENCE LOZANO" <JEEPER at netins.net>
To: <r-390 at mailman.qth.net>
Sent: Friday, June 17, 2005 7:14 PM
Subject: [R-390] R-390 BALLEST/HELP


IF I REMOVE THE BALLEST,WHICH WAY WOULD BE RELIABLE AND SAFE.REPLACE THE TWO 
6BA6 TUBES WITH 12BA6`S  THEN ADD JUMPER WIRES IN BALLEST TUBE SOCKET.OR 
KEEP THE 6BA6 TUBES AND PUT IN THE 47OHM RESISTORS?
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