[Prev][Next][Index][Thread]

Re: Tubes/FILAMENTS



-- BEGIN included message





Re: "The filament supply for high-voltage tubes (X-ray or trans-
        mitting) =must= be isolated from ground to a degree equal to
        the =peak= voltage to be applied to the plate (or anode) of
        the tube.

        The official way to to this is with special filament trans-
        formers which are insulated as between primary and secondary
        for the high voltage.  These can be quite costly.

        However ---

        For us experimenters there are two simple work-arounds:

        1) - Use a Battery on an insulating stand."

	About 45 years ago I had a serious accident due to using
a 2V storage battery to heat the filmament of a HV rectifier I
was using with an X ray tube.  Running whole setuf of 20 kV transformer
and voltage doubler using RK-72 rectifiers in the DARK, had a spark
from somewhere touch off the hydrogen in the case of one of the
little storage batteries, which promptly came unhinged and blew 
"battery acid" all over the garage, a car sitting there, into my
eyes, etc.  All the time with haywire HV leads running around IN
THE DARK!!!!!  Learned my lesson but want to warn anyone using
storage batteries to run at HV to be extra careful with hydrogen
explosions.  The batteries were (and still are) a neat way to go,
but be careful!
Ed Phillips






-- END included message