Eimac 250T

[W8ACR]

I recently acquired an Eimac 250T - NOT a 250TH or 250TL. The designation on the glass envelope is 250T.

There are some additional characters inside the envelope down low where the filament leads come up from the base.

"0-209-HI"

I assume this tube is the equivalent of the 250TH. I think that the earlier versions of the T series tubes were marked either "HI" or "LO" inside the envelope. Later versions were marked TH or TL on the outside of the envelope. Is this correct?

Thanks, Ron

[ae7db]

Your supposition sounds likely to be correct.  Attached is an Eimac data sheet that specifically says the "LO" is marked on the filament stem for a 250TL, so it seems reasonable that if yours is marked 'HI" it is an early 250TH.

Dean