I am trying to decide between tertiary winding for cathode fedback to be run with a pentode connected final, or U-L in the traditional fashion. I also don't quite know where the u-L point exists for the 813, that is at what percentage should the tap go. A tertiary winding that is ~30% of the anode winding takes up a lot of room. I don't think of any over ~15%, like Acro's 350 and Dynaco's A441. I have a pair of 441's and they need to be better. they are acceptable, but that's about *IT*. I need a stellar one...

I think I will go with a cathode tertiary winding. It will net me ~80W without getting to nutsy with dissipation and I can put g2 right where I want to. Fortunately I have a reasonable design OPTx for both apps. I just need to decide.

On the schematic distribution. I am going to draw them tomorrow and the next day. Such things need a good proofing I can say with confiddence. Also notes on limitations, and variations. more importantly Limits are a personal requirement. Then off to the scanner and ~4 pages at ~1 meg each ought to be fine resolution.
regards,
Douglas

I look forward to hearing the "whys' of your final decison.

Russ

I read somewherre tht the CFB, if kept to ~10% reduces third H a bit more than just that amount of nfb would from g2 current contributions. Even with the so-so Dynaco OPTx, and more than 10% it did not sound 'souless' or dry. The leakages caused some interesting behaviour with certain connections, and I decided to try something else.

Either way, it is only a pair of OPTx, probably ~$400/pr, and I may get the main plate TX wound so I can use it for both U-L @ 700V B+ or the full 1kV for pentode conection. But until I get some funding improvement( and keep the schedule open enough to build ), I am not having either one wound. I don't think I will be certain until I do it both ways anyway, so I'll probably get both done and stop wondering.
regards,
Douglas

Don't want to seem impatient!

To date I have only recieved pieces 2 & 3 of the schematic. What is the status on the rest?

Joe

I am making a more complete set of schematics, and will send them to the forum projects files managed by Wayne. A bit more patience please, I will deliver this as promised. Figure Monday by thetime I can distribute the scans( even a pre-liim proof found mistakes and omisions, this must be done right the first time ).
regards,
Douglas

Understand! Take your time. Just knowing is half the battle.

Joe