Posted by Tnuctipun [ 64.12.116.14 ] on February 09, 2005 at 18:11:11:
In Reply to: Re: schematic posted by GarMan on February 09, 2005 at 11:02:50:
Considering the standard applied to PP transformers with regard to a-a impedance and primary inductance, it amazes me how easy this is to sidestep for high Z SE.
It is bad enough gettig primary L w/o an air gap, let alone one to allow 130-140 mA of idle current.
Put a U-L rigged 813 at ~700 volts and load it with a 5k:8 OPT and it will have a chance. 2Pi*20cps*L to equal more than 7k is not too bad. 50-60 Hy will be adequate.
I think I'll stay PP, 10k:8 is *EASY* and inexpensive( and I like PP better anyway so far ). I'm thinking a little cathode feedback from a tertiary winding, a bit of plate-to-grid with the E-Linear driver, and I'll be in good shape.
I can take a core with ~5 square inches of good Iron and get good 20-20 performance out of it to more than 60 watts. Been looking for an excuse to try the new amorphous C-Core. Probably best to R&D with M6 in the early stages.
too many cool things to do, that's for sure. The 813 ought to be good practice for a PP amp running TX pentodes at 350W/plate dissipation...
regards,
Douglas