Output transformers - Printable Version
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Output transformers - Patrick - 07-19-2018
How critical is the primary impedence of the output xfmr? I'm talking specifically about 6V6 push-pull. If the wattage is similar, and the secondary impedence is correct, how much impact will variances in the primary have. The reason I'm asking is, I have a universal push-pull xfmr with variable primary from 1200-25000 Hz, but the schematic shows a 700Ω primary.
RE: Output transformers - loepke72 - 07-19-2018
700 ohms sounds more like the DC resistance. The impedance is probably more like 7000-8000 ohms plate-to-plate. It's not overly critical, just don't get too far away from this value.
RE: Output transformers - Patrick - 07-19-2018
(07-19-2018, 03:53 PM)loepke72 Wrote: 700 ohms sounds more like the DC resistance. The impedance is probably more like 7000-8000 ohms plate-to-plate. It's not overly critical, just don't get too far away from this value.
I think I've forgotten everything I use to know. How would I determine the input impedence? Plate voltage is supposed to be 273V, 15W output, 700Ω DC resistance?
RE: Output transformers - loepke72 - 07-19-2018
Impedance ratio is the square of the turns ratio, but that might be hard to measure if the transformer is bad. IIRC the load impedance given in the tube manuals for push pull 6V6s is 8000 ohms. Much more than that and power output falls off, much lower and distortion rises and power output falls off as well.
RE: Output transformers - Patrick - 07-19-2018
So generally speaking, 7k-8k would be appropriate with a 6V6 configuration since we're only dealing with occasional AM listening?
RE: Output transformers - loepke72 - 07-19-2018
I think it would work just fine.
RE: Output transformers - Patrick - 07-19-2018
Thank you.
RE: Output transformers - codefox1 - 07-23-2018
Tubes are not that picky about matches - within limits-. Neither are speakers or ears for that matter.
RE: Output transformers - Stan the Man - 08-24-2018
Will this help??
RE: Output transformers - Patrick - 08-24-2018
Good reference. I'll keep that. Thanks,Stan.