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In Reply to: RE: Are these military potted trannys? posted by BofService on March 11, 2017 at 10:01:23
I really like those big potted trannys, moving them around is how i get my exercise. If it were from the Navy it would have an "anchor" logo stenciled on it. I would think it must be derated some, maybe 5% maybe more? Have you decided on what kind of amp you want to build? I am on SEP kick now so i would vote for 6L6 type amp with fixed bias. That way you could experiment with higher power tubes like 6550 as you can try different tubes in the family with just adjusting the bias. If you use the "RH" type circuit it only requires a single 12at7 driver tube but you can also use the 6sl7 or 6sn7 with the rh universal circuit.
Good thinking DAK. Last year I built an RH "Universal" that allows me to experiment with the 6L6 family, including the 807 and 1625 (of which I have several). It turned out good, and I appreciate Alec Kitic's design and documentation efforts on that amplifier.
On this amp I'd like to build with 300Bs and CCS 5842 drivers. Since the B+ from my transformer seems well regulated, that encourages me to think it will work with any tubes that run well at 60ma (or less), 300B included.
Last night I used PSUD to design a separate power supply using the PT's 235-0-235 winding and a couple chokes I have on hand. The supply gives me about 256vdc with .005 v of ripple at 28ma. This should work nicely for a 10M45 CCS and a 5842 per channel. My thoughts are to use the TubeLab "Simple 45" schematic for the driver stage. There are all manner of examples out there for how to do the OP stage. I'm looking at the "sjselectronics SE104it" schematic as a model for the OP right now. I have a pair of Hammond 125ESE OPTs I can use for breadboarding, and invest in some better iron later. I think I have everything else on hand except the OP tubes.
I'd consider trying the TubeLab PowerDrive topology, but I don't quite understand how it works, nor how I would implement it with 2 separate power supplies, nor whether it could work without a negative supply. Also there is the issue that the Toshiba 2SK2700 MOSFET has been deprecated. Which of the analogs are people using to replace it?
Awesome, it always helps to have a plan in place to help guide your project along. But, regarding, SS stuff i am not a convert, yet. I still find that even using an LM317 device to be a hassle since it is much less reliable than a resistor.
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