Here are my thoughts.
You definitely have insufficient current capacity in the 289V winding. Your transformer would probably only be able to provide 100 mA out of a voltage doubler. THe triple-tube PA in a TR-4 needs roughly 300 - 350 mA to be happy.
You may not have enough current capacity in the 207V winding.
In any dual-primary transformer you need to parallel both primaries @ 115V to get designed-for core flux for total rated secondary current. So you can't use one of the primaries for a bias winding.
By way of reference, Peter Dahl's exact replacement for the AC-4 transformer specs out as follows:
PR) 120/240 VAC 60 HZ 1 PH
S1) 265 VAC @ 750 MA CCS
S2) 90 VAC @ 350 MA CCS
S3) 95 VAC @ 100 MA CCS
S4) 12.6 VAC @ 5.5A CCS
Keep in mind that an AC-4 is barely able to power a TR-4, so if anything you should be thinking about more power capacity than a stock AC-4.
AC-4s aren't expensive or rare; why are you trying to homebrew one?
regards,
Mahlon - K4OQ
JJ HO wrote:
Dear drake lovers,
I am in the process of building a simple PS for TR4. Judging from the circuit of AC4, I need a transformer that can supply HV (~ 750V) and MV (~250V) and LV(~ -70V).
I got a transformer with the following 2nd AC terminals:
- 289V/200mA: this can supply around 750V with voltage doubling rectifying scheme.
- 207V/200mA: this can make a 250V.
The transformer had a 120/230V selection. I wondered if I could use one of the 120V primary as a AC source for providing this voltage.
Also, for a 110V operation, do I need to connect the two primary coils in parallel or I can leave one as is.
Thanks for you answers and helps.
73,
Jonathan
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