Well, since we've had so many good questions and answers about power supplies I think I'll jump into the fracas and ask some VERY rudimentary questions, but first some back ground…
I’m trying to build a junk-box tube amplifier. That alone is the motivation.
In essence I want the simplest possible amplifier with solid state rectification. Using these criteria I deduce that I’ll probably be building some 1.25Watt single-channel, single-ended “thing.”
At the base of this construction is a nearly-new power transformer that I have kicking around, a Hammond 269EX that is rated at 115V primary and 190-0-190 Vp-p. This is a remnant of a failed attempted at a headphone amplifier I tried to build earlier in the year.
Oddly, the transformer seems to put out much closer to 220Vp-p rather than 190Vp-p. I checked my mains voltage and it was 119.65Vac, so that explains a couple extra volts, but not 30.
The low voltage heater circuit also reads 7.4V, rather than 6.3. I even stuck a 6L6 tube on the heater secondary to load it down and see if it dropped (magically) into place…it did not.
I also stuck a simple center-tap rectifier on the circuit, and un-surprisingly the rectification was 440volts. If I loaded this circuit down with the normal HV amplifier load would the voltage fall in-line also?
Otherwise, what’s going on with my transformer? Did they forget a few primary windings or something?
Does anyone have any tips on building ‘the simplest/cheapest tube amplifier ever’ from the fore-mentioned transformer and any combination of the following tubes:
12AT7
12AU7
12AX7
5879
7199
6189
6077
6CG7
Thanks for the input guys, and thanks in advance for baring with me.
drew*