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Re: [Amps] Clippertion L 572B tubes

To: "John." <>, <>
Subject: Re: [Amps] Clippertion L 572B tubes
From: "Tom W8JI" <>
Date: Tue, 10 Jul 2007 12:26:54 -0400
List-post: <>
I am in the process of restoring a Clippertion L amp.  Any 
thing that I
should look at that has been a problem ?>>

The Clipperton like many Dentron amps has some major issues.

The tank coil for 160 is too close to the cover and may not 
work well on 160. In some models they added enough C to make 
it work, but the tank Q is really pretty far off.

Be sure you change all the resistors across the 
electrolytics. They used carbon and they are a source of 
failures that kill the electrolytics. Use metal films.

If the amp has resistors across the rectifiers, remove them.

The filament dc current return in some Clippertons is off 
one side of the transformer (most have no filament CT) and 
that makes some low level AC hum.

The amp is notoriously unstable on 15 and 10 meters because 
it has 4 unneutralized tubes in parallel. You can always be 
sure to have the loading control very far open to stabilize 
the amp. The best thing to do would be to neutralize the 
amp, but that is probably beyond the scope of what might 
easily be done. A second solution would be nichrome or other 
lossy materials in the anode circuit. This would de-Q the 
amp at HF and waste some power, but it would help stabilize 
the amp on 15 and 10 meters.

You also might add some meter protection.

73 Tom

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