[R-390] T603 transformer

[Renee K6FSB]

oh yes I forgot about that issue....I had been working on an A 
recently......you are correct, thank you!
I recall now, I used a resistor for the replacement 6ak6 fil and used a 
12aq5 , added wire from CT of 25V  and IIRC 250ma current
Renée, K6FSB

On 12/28/24 11:09 AM, Jacques Fortin wrote:
> 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
>