Back in the '80's I rebuilt the cavity in a BTF-20E (not an E-1) and was getting 23KW with an Econco rebuilt. Ron D ----- Original Message ----- Steve Brown wrote: >>>I put one in a BTF-20 ~6 months ago. It tuned up better than any >>>tube I'd >>>seen in a long time ( Not a hog for screen current like brand E.) >>>and is >>>pumping 25kw, untouched >