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Re: [Amps] Drake L-4B PSU burned resistor

To: amps@contesting.com
Subject: Re: [Amps] Drake L-4B PSU burned resistor
From: Alan Ibbetson <alan@g3xaq.demon.co.uk>
Date: Tue, 1 Nov 2005 23:09:34 +0000
List-post: <mailto:amps@contesting.com>
In message <ac2be72401684c739d03a4198d0ddd80@somis.org>, R. Measures 
<r@somis.org> writes
>The first things I would look at is the tubes, testing them for 
>filament-grid breakdown potential.

No hi-pot tester here, but seeing as the valves are somewhat low on 
emission I might invest in a pair of new ones on my trip to CA next 
week.

>   Next, I would measure the R of the VHF suppressor resistors.

They measure OK.

>This requires a larger resistor - such as a 10W surge protection type 
>of approximately 10 to 15 ohms.

The 10 or 14 watt ones commonly available from the big UK supply houses 
are wire wound vitreous enamel types, with a maximum voltage rating of 
only 500 or 750v. I guess I'll need several of these in series, not so 
much for the power rating as for a breakdown voltage safety margin. 
Messy, but just doable within the rather cramped confines of the L-4B 
PSU.

Thanks very much for all the helpful replies I've had, both on and off 
the list, and for the several offers of components. The ham spirit ain't 
dead yet!

-- 

Cheers,

Alan G3XAQ
alan@g3xaq.demon.co.uk

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