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Re: [Amps] Testing Tubes with a Henry 2K

Subject: Re: [Amps] Testing Tubes with a Henry 2K
From: "Mike McCarthy, W1NR" <>
Date: Sun, 22 Aug 2021 07:58:30 -0400
List-post: <>
Well... My 2K (original) is wired in parallel. It is also designed for
3-400's and won't accept a 3-500 unless you change the chimneys and
change the heat dissipation caps to low profile ones or lower the sockets...

Mike, W1NR

On 8/21/2021 10:40 PM, David Gow wrote:
> The Henry 2K series amplifiers have the filaments in series
> so yuoust always have two tubes in the amp..  The manual explains why Henry
> made this choice.  You can test a tube by having one known good tube in the
> amp as a constant.  After done with the spare tubes put the best in the amp
> instead of the original constant tube.  The measurements will be relative
> but at least you have some indication of usefulness.  I love my 2K--3 but
> to test tubes I use my SB-220 which has filaments in parallel
> Dave W7VM
> On Sat, Aug 21, 2021 at 7:24 PM Brett Sims <> wrote:
>> I have three used 3-500Z tubes I'd like to test.  Can I safely test them
>> one at a time in a Henry 2K?       My thought is this will allow me to
>> better classify each tube individually and perhaps better match two of the
>> tubes.  Providing the tubes prove useable.
>> Not sure it matters, but the Henry has had the HV power supply upgraded
>> with new electrolytic caps and the rectifier tubes replaced with high
>> voltage "potted" diodes.
>> Any thoughts or comments?
>> Thanks  Brett  N5SQK
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