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[Amps] Testing Tubes with a Henry 2K

To: "" <>
Subject: [Amps] Testing Tubes with a Henry 2K
From: Brett Sims <>
Date: Sun, 22 Aug 2021 21:02:19 -0500 (CDT)
List-post: <>
Appreciate the responses.  My Henry 2K also has the filaments in parallel.  
Your right, it was originally designed for 3-400's.   I failed to mention in my 
original post, it was upgraded to 3-500's with appropriate chimneys and caps.   
  It works great.

So if you have a Henry 2k with filaments in parallel and currently runs two 
3-500Z's with appropriate chimneys, could one test a single tube?   Wadda ya 

Thanks  Brett   N5SQK

Date: Sun, 22 Aug 2021 07:58:30 -0400
From: "Mike McCarthy, W1NR" < >To:
Subject: Re: [Amps] Testing Tubes with a Henry 2K

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 you must 
> 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
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