Re: [Amps] PL172 (8295)

["Roger (K8RI)" <k8ri@rogerhalstead.com>]

I agree with Carl, I haven't seen a good PL172 (glass seal) in ages. The 
ceramic versions seem to hold up well.
I have an HT32B

73, Roger (K8RI)


On 5/6/2017 Saturday 11:46 AM, Carl wrote:
> The original PL-172 with glass seals is NOTORIOUS for air leakage and 
> not outgassing from the anode.....big difference.
> Carl
>
>
> ----- Original Message ----- From: "RAY FRIESS" <rayfrijr@msn.com>
> To: <Amps@contesting.com>; <chris@g3vbl.co.uk>
> Sent: Saturday, May 06, 2017 11:32 AM
> Subject: Re: [Amps] PL172 (8295)
>
>
> > I would not be too concerned about leakage.  It happens, but very 
> > very seldom.  I have tubes that are still new in box from way back in 
> > WW2 that I have used and none have ever shown air leakage.  Easiest 
> > way to determine if they are still good is to plug them in and fire 
> > up the rig.
> > Ray  wa7itz
> >
> >
> > ________________________________
> > From: Amps <amps-bounces@contesting.com> on behalf of Chris Pedder 
> > <chris.g3vbl@gmail.com>
> > Sent: Saturday, May 6, 2017 8:11 AM
> > To: Amps@contesting.com
> > Subject: [Amps] PL172 (8295)
> >
> > 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.
> >
> > Chris G3VBL
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