[Amps] PL172 (8295)

[Ron Youvan]

   Chris G3VBL Pedder wrote:

> For the last 37 years my Hallicrafter HT33A has been sitting on the floor
> in the garage with an 8295A (Ceramic) fitted. I have a pair of 'new in the
> box' PL172s one of whose boxes is still sealed. Packing date was 6/67 so
> that's almost 50 years.
> I suspect that the glass seals will have leaked but is there anyone with
> experience of these tubes after such a long period of time. If I were to
> construct a hi-pot device, what sort of values should I expect from a
> 'good' tube? Thanks.

   There is a procedure to test tubes for gas intrusion, which I forget
other than it is done K to G with a completely cold cathode and about
300 Volts.  google can be your friend
-- 
   Ron  KA4INM - Youvan's corollary:
                 Every action results in unwanted side effects.