scrounged power xformer

[mbailey]

what amp could I build with this?
from label on bell
Stancor p-8359
sec 380v@70ma or 320v@70ma ct
6.3v@.6A
6.3v @ 3a

[Bruce / Mission Amps]

what amp could I build with this?
from label on bell
Stancor p-8359
sec 380v@70ma or 320v@70ma ct
6.3v@.6A
6.3v @ 3a

Except for probably needing a SS rectifier, A 6V6/EL84 Champ, a SE 6V6/EL84 Princeton, an AC4, a small 10 watt 2xEL84 or 6V6 amp... tons of possibilities if you mentally keep the total output power within reason.

[mbailey]

thanx bruce

[Enzo]

It has the extra one-tube 6v winding, I'd assume for a rectifier. I have little experience with the 6v rectifiers. WOuld something like a 6X4 work? Oh wait... center tapped. Maybe not.

[Bruce / Mission Amps]

It has the extra one-tube 6v winding, I'd assume for a rectifier. I have little experience with the 6v rectifiers. WOuld something like a 6X4 work? Oh wait... center tapped. Maybe not.

I bet that 6X4 is the rectifier this was made to be used with.
He didn't say if it was center tapped though, so.. !?
An extra pair of, anode grounded 1N4007s would fix that if it the Hi-v secondary isn't center tapped.

[mbailey]

the 6.3v @ .6a is center tapped
the 6.3v @ 3a is not
the high voltage secondary is c.t.

[Enzo]

The HV CT was my concern. 320ct is only 160VAC to rectify with a straight recto tube. To use the entire winding, a tube recto would have to be used in half wave rectification.

[Bruce / Mission Amps]

The HV CT was my concern. 320ct is only 160VAC to rectify with a straight recto tube. To use the entire winding, a tube recto would have to be used in half wave rectification.

My old 60's Walker Radio parts book doesn't show this model #. Only a couple of the other P-8??? series are for a half wave rectifier... most all of them seem to be x-0-x volts PTs. How many high voltage secondary wires are there?

Not sure how high he wants the B+ but maybe for a little better filtering.....
Assuming it is a half wave rectifier PT, I'd be inclined to use the lower voltage winding and the 6X4 with the two 1N4007s like in the picture I scratch drew here:

Ahh. I just read he says the Hi-V is center tapped... so just don't ground the center tap wire and use it like I drew this thing below....

[Alex R]

The AC10 uses an EZ81, that and the EZ80 are 6.3v heaters. The AC10 has the EZ81 heater on the same circuit as the other heaters, which causes major issues when there is a short in the rectifier. I have replaced two PTs in AC10s recently. Alas too much current in the AC10 circuit for this PT I think.

[6267]

I'd second using EZ81, they're surprisingly long lasting for little bottles. If it were me, I'd try to do a SE EL34...40-50ma for the power tube, leaving 20-30 ma for preamp (should be enough even for a reverb driver). 3x.6A=1.8A+(EL34=1.25A?)=3.05A. No data sheets on this computer, could be wrong on the current draws. Looks like 3 preamp tubes and an EL34...more power out than a SE 6v6, still the great SE tone. The OPT won't be the cheapest though.

[Bruce / Mission Amps]

I think if the builder is going to use a relatively stiff rectifier like a 6CA4/EZ81 he ought to just use the lower 320v secondary with four very cheap, 1N4007s in full wave bridge.... or buy a 800v FWB rectifier block.
Either will save the cost and hassle of the tube socket with the wiring, all together.

[6267]

Good point Bruce, I was thinking he wanted a tube rectifier for some reason. That would also leave the rectifier heater winding for other purposes, maybe filtered DC for the first preamp.