[R-390] R390A to R725 conversion question

[Tom M.]

 Perry,
The added transformer in the R-725 was for PTO hum bucking, not filaments. sk Wally Chambers informed me of that fact.

The R-725 had the rewired R-390 filaments.  I've done this myself and wrote a procedure how to do it. I agree with you it was a bit of a PITA.
I use the converted IF deck in my daily driver R-390A to this day.
Tom




    On Wednesday, October 30, 2024 at 04:31:35 PM CDT, Perry Sandeen via R-390 <r-390 at mailman.qth.net> wrote:  
 
 List,
IIRC I've seen 3 published articles for r390a to r725 conversion all using the re-wiring of the R390 IF to 6 volt filaments.  This seems to be a big PITA.
When the military did the original they just added another 26 volt filament xformer. This seems a much easier approach especially when we have small SRPS's available.

If anyone would have the schematics or TM addendum I would appreciate it if they would contact me off list.
TIA
Perry
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