mac wrote:
I am looking for schematics and any other help in making one tube CW QRP
transmitter for 80m band, BATTERY operated. I think about 3s4t or 1t4t
(DL96, df96).
What is minimal anode voltage (typical is 67,5v) which I can use with
this lamp?

You'll probably get better answers, but...

I once had an old MW radio that used tubes of this kind. It worked fine
with only 18V on the anodes. (two 9V batteries in series)

--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com