[Boatanchors] Dear Smart People: "Zombie" 811s??

[Glen Zook]

The manual for the 30L-1 is available from the Collins Collectors' Association website at no charge.  Because of the size of the files the manual is available in several parts.  Go to

http://www.collinsradio.org/?page_id=75


and then scroll down to the 30L-1 files.
 
Glen, K9STH


Website:  http://k9sth.com


________________________________
 From: David Stinson <arc5 at ix.netcom.com>
To: boatanchors at theporch.com; boatanchors at mailman.qth.net 
Sent: Saturday, June 23, 2012 9:08 PM
Subject: [Boatanchors] Dear Smart People:  "Zombie" 811s??
 
I'm working on a Collins 30L-1 amplifier. 
First time I've ever messed with one 
and I haven't done much with any amplifier. 
Had to repair the metering circuit, replace the
"fuse" resistor in the HV lead, and "Un-bypass"
all the interlocks.  This guy was asking to die.

The four 811 tubes in it look fried; discolored
plates, stained glass etc.  All the DC paths and 
high-voltage and cathode paths check-out. 
30 watts of drive on 75 mtrs gives no plate current 
and only a few watts out.  I don't have a manual;
is this amp supposed to have some idling current?
Funny... all four of the 811s test as 
"good" on a TV-7 tube tester.   I'd expect this 
would mean they so have some emission.
Is it possible they would draw current with the 
static voltages in the TV-7, but not draw current 
when driven by RF?   Are they "zombie" tubes,
being "un-dead?"


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