[Amps] Holding a vacuum

[Kimberly Elmore]

I always thought that a gassy tube is essentially a short when HV is applied, or perhaps like a thyratron: once current is allowed to flow by the control grid it can't be stopped until the cathode line is opened. Gas-filled rectifiers, such as the 3B28, 866A, etc., or the gas-filled VR tubes are examples. Is there an "in between" state where a tube is gassy and works fine except for excess plate current? 

Kim N5OP


________________________________
 From: Bill Turner <dezrat at outlook.com>
To: Amps group <amps at contesting.com> 
Sent: Monday, December 1, 2014 11:38 AM
Subject: Re: [Amps] Holding a vacuum
 

------------ ORIGINAL MESSAGE ------------(may be snipped)

On Thu, 27 Nov 2014 19:15:08 -0500, you wrote:

>What metric does one use to determine if a given tube holds a vacuum or not?>
>Cheers,
>
>Karin   K3UU

REPLY:

Tubes that lose vacuum draw excess anode current even when idling and
if they are glass, one can see a blue glow in between the elements
when HV is applied. 

73, Bill W6WRT
_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps