[Amps] The H&K 304H

[Edward Swynar]

Many thanks to all who took the time to respond to my query about the old Heintz & Kaufmann 304H (their version of the Eimac 304TH, per Lud's note to me)...

Well, research into my radio shack library here revealed that the 304H is most certainly NOT a good candidate for grounded-grid service: a piece in a 1954(?) issue of QST described just such an arrangement, & stated that for a kilowatt (approx.) input, a single g-g 304H would need 120-watts of drive!

Hardly promising.

However, I did take heart when thumbing through my 1980 edition of the ARRL HANDBOOK: there's an interesting low-band "junker" design listed therein that incorporates a grid-driven 833A. The article makes mention of the possibility of using a 304TH in its stead, & published specs say that such an arrangement would need but 30, or so, watts of drive...ideal.

As I mentioned to Lud, I could lash together a robust enough filament voltage provider that would easily power up either an 833A, or a 304H: then, with the filament "sockets" paralleled, and allowances made for room, I could run either tube in the circuit, as dictated by availability & interest...

...One tube at a time, of course!

~73~ Eddy VE3CUI - VE3XZ