Posted by Tnuctipun [ 172.170.249.53 ] on January 20, 2005 at 21:27:06:
In Reply to: Who's on first posted by colinhester on January 20, 2005 at 21:06:11:
The PS choke is a bit on the expensive side. If we stick to a max of 20 mA load the Hammond 30 Hy/40 mA choke shold do fine. I got the big one because I want to run 40-50 mA and need a bigger choke. Don't feel it is absolutely rquired...matter of fact I have heard 5687 sound good from a few mA on up. We do need to hit critical current for the choke input PS filter, so 7 mA per valve is probably a reasonable min. I wanted to get away from such a small window. Using the choke in a L-C filter reequires de-rating its maximum current, 40 mA to ~25 seems reasonable.
The PS with the custom power Iron will use two diodes. I suggested using the 6CA4 which is a pair of diodes in the same envelope, sharing a cathode( which we'd tie together anyway ), and a 6.3vac/1A heater for its indirectly heated cathode. The high voltage winding will have its center tap grounded( probably best to attach directly to the capacitor, and do a single ground point, a.k.a. star grounding.
This site keeps comming up when I search for a drawing. V1 and V2 can be a single valve( GZ34/5AR4 or 6CA4 ), or as drawn if you decide to use damper diodes, which come one diode to an envelope. The resistive load is of course substituted for our amplifier section.
regards,
Douglas
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