[R-390] T603 transformer

[Jacques Fortin]

Hello Renée,

First part of your suggestion below: OK, I will do the same.
But replacing the 6AK6 in a R-390 (non-A) by a 6AQ5 is not easily feasible.
The R-390 tube filaments are wired in series and powered from the 25.2V filament supply (no 6.3V winding there).
The 6AK6 filament rating is 150mA, the 6AQ5 is 450mA: see the problem ??

Either Kevin "extract" the defective transformer and rewind it (see attached document), or he use a Hammond 125ASE as the replacement and then will be able to connect a 4 or 8 ohms speaker directly.

73, Jacques, VE2JFE in Montreal


Kevin -
possible suggestion,
move T602 to T603 fixes the line audio issue, replace the the now empty
T602 with standard table top radio xfmr 5K to 8 ohm AND replace V603 with 6AQ5 ...some circuit changes required (simple cookbook) and do put a load on output of line audio 2W 560ohm to prevent future failure I have had to do this for a couple of R390s this mod does eliminate any extra transformers to run 8 ohm speakers, better audio too.....
similar can be done for R390A
Renée, K6FSB

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