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Re: [Amps] Collins 30L-1 / 572's B

To: "k7fm" <k7fm@teleport.com>
Subject: Re: [Amps] Collins 30L-1 / 572's B
From: R.Measures <r@somis.org>
Date: Mon, 20 Sep 2004 02:55:12 -0700
List-post: <mailto:amps@contesting.com>

On Sep 19, 2004, at 7:25 PM, k7fm wrote:


Rich said:

"With 1700VDC on the anode, there would be virtually no advantage to 572Bs
for SSB."


Well, maybe not if you have no problem with holes in the plate. Many years
ago, before I realized that you should have about as much plate dissipation
as you have output to be safe, I burned a hole about the size of a dime in
an 811A. The 572B is much more tolerant to normal abuse because of the
superior plate construction. Even normal tuneup can push the envelope of
the 811A. No, you will not get any more output - but if the 572B tubes are
available they should last longer.

Colin -- 'Normal' tune-up for an 811A or a 4-65A is Not to use NØN (hammer-down) tune-up due to it's delicate anode. A tuning pulser is a safer method of tune-up for SSB or CW. Another method is a string of 50wpm dits. Also, the 30L-1 does not have a HV PS that maintains good V-regulation with NØN, so there would be a slight error with a hammer-down tune.

Colin K7FM



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Richard L. Measures, AG6K, 805.386.3734. www.somis.org

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