[Amps] NOS 811's & 30L1

Carl km1h at jeremy.mv.com
Wed Sep 21 14:53:05 PDT 2011


----- Original Message ----- 
From: "Mike Lord" <k4elv at bellsouth.net>
To: <amps at contesting.com>
Sent: Wednesday, September 21, 2011 3:25 PM
Subject: [Amps] NOS 811's & 30L1

>I just completed the restoration of a 30L1, i.e., new Harbach board, 
>"matched set" of 811's.  Brought the unit up slowly with a Variac.  110 VAC 
>line voltage, 1800 VDC unloaded on plates.  All seemed ok.  Hooked up the 
>unit to the rig.  Turned the 30L1 on and blew up the glitch resistors. 
>Smoked up the place.  Checked the unit for damage beyond the glitch all 
>checked ok.  Brought the unit up slowly with the Variac and at about 400 
>VDC one tube began showing purple glow and slight arcing.  Changed out the 
>tube and all was well.  Here's my question.  The 811 vendor tells me the 
>problem is the 1800 VDC on the plates.  "Too much for an 811"  I realize 
>the caps on the Harbach are large thus more B+, but there have been many of 
>those boards sold.  The 30L1 book says 1600 VDC unloaded.  The 811 is rated 
>at 1500 V.  So what are all the 30L1 owners doing besides changing over to 
>a 572B?
> Thanks.  Mike K4ELV
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