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Re: [Amps] L4B startup after a long sleep?

To: Stan Gammons <>
Subject: Re: [Amps] L4B startup after a long sleep?
From: Bill Weaver <>
Date: Wed, 12 Dec 2018 14:19:55 -0500
List-post: <>
I'm about to do the same thing with an Alpha 86. I thought it may be a good 
idea to remove the tubes until the caps have proven good then re-perform the 
exercise with the tubes in place.

Bill - WE5P

> On Dec 11, 2018 at 23:42,  <Stan Gammons>  wrote:
>  I would set the meter to grid current and use a variac to first power it up. 
> Unless you have a 240 volt AC variac, you may have to rewire the power supply 
> and RF deck for a 110 volts AC variac. There might be a loud bang if one 
> plugs the amp in and just turns it on. Tubes could be gassy from setting so 
> long and arc over when full plate voltage is applied. Harbach makes a 
> replacement power supply board for the L-4B and the L-7. I think that board 
> is what I have in my L-4B power supply. Good luck with the amp. The L-4B is a 
> nice old American made amp. 73 Stan KM4HQE On 12/10/18 4:53 PM, Ray LaRue 
> wrote:  >  The local club here has inherited a very nice L4B amplifier that 
> we  >  suspect hasn't been run in about 10 years or more. On a scale of 1 to  
> >  10 with 10 being new, this is a very nice 9. I have been asked to  >  
> reform or replace the filter caps and bring it up on line.  >   >  As I've 
> never worked on an L4B, I would appreciate any experienced  >  tips or 
> no-nos, as !
 I begin t
o dive into it.  >   >  Any assistance would be appreciated.  >  73,  >  Ray, 
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