[Kenwood] TS-520/TS-520S Neutralization

Sat, 24 Apr 2004 08:31:21 -0600

I got my information and 6146 tutorial from Glen Zook K9STH, who is an 
acknowledged expert
on 6146 tubes and their successors.  He has answered the question about 
using 6146W tubes
many times....   I have used them in one of my ts 520 rigs for a couple 
years now without any
problems at all.  When the original tubes in my second ts 520 go, I will 
replace them with W's
as well.   I have 100 of the tubes........   all brand new.
Here's his web site and here's a portion of what he said just recently...

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

Unless you want some pretty "hairy" experience with
neutralization (and they may or may not neutralize) do

not use 6146B tubes or any 6146W tubes with a "code
date" later than 1964 (which are basically the same
tube as the 6146B).  Sometimes the 6146B works in
equipment that was originally designed for the
6146/6146A/8298 series, but using the 6146B/8298A
often results in all sorts of problems.

Larry, K4WLS wrote:

>6146W's are NOT a direct replacement for 6146B's. The
>6146W's are the miltary version of the 6148B. Nice thing
>about the 6146W is they are built to Mil Specs and are more
>rugged than the 6146B. They were originally conceived to
>run in the old military VHF equipment. Big problem, the plate
>dissipation power of the 6146W is only 75W compared to
>90W for a 6146, 5146A, and 6146B.
>
>The 6146B has a plate dissipation power of 90W, so two
>of them in parallel can be run at 180W input on CW.
>
>The 6146W only has a plate dissipation power of 75W, so
>two of the can be run in parallel for 150W input on CW. If
>you are running 6146W's better lower the Drive Level on
>CW or the Mic Gain on SSB. Otherwise you are risking
>lowering the life of the tubes, failure of a tube, and associated
>damage to other components in the finals, especially the
>sreen grid resistors.
>
>Plate Dissipation Power (Power Input per Tube) = 1/2 Ip
>(total plate current - actually cathode current minus screen
>current) X (plate voltage or key down HV on meter). This is assuming both
>tubes are perfectly matched and are conducting the same amount of current.
>Unless you have a matched pair of finals (which you should always run in
>parallel power amps), most
>likely one tune is conducting more than the other. All the more
>reason to stay away from 6146W's.
>
>If you have 6146W's in your rig, tune up on CW and advance
>Drive Level to 225 mA (180W input with key down HV of 800V).
>Hold key down one or two seconds and watch Ip start
>dropping. Hold key down longer and listen the the crackling
>as the plates start getting very hot as the plate dissipation
>power is being exceeded. If rig covers were off, and final
>cage removed, hold key down a bit longer and watch the plates
>start glowing cherry red as the crackling due to heat gets more
>intense.
>
>If your key down HV is more than 800V, do Ip = Key Down HV/
>180W to get the Ip to advance the Drive Level to, to try this little
>test on 6146W's.
>
>If you use 6146W, they only good for 150W input - you should
>always run a matched pair of 6146B's in your Kenwood tube
>rigs for best performance.
>
>Also, you most certainly can use a 6146 or 6146A as a
>replacement for a 6146B in all TS-520 thru TS-830S as
>long as the tubes are good.
>
>You guys need a good Transmitting Tube Manual such as that
>put of by RCA or GE, EIMAC - they are still in print.
>
>Larry,  K4WLS
>
>From: "Ray Friess" <[email protected]>
>Subject: Re: [Kenwood] TS-520/TS-520S Neutralization
>
>
>Don:
>I also have a ts 520 .... two of them in fact.  I recently retubed the
>finals in one of them using
>6146W tubes and have had no trouble with neutralization once done.
>The 6146B is the American version of the finals that come with the
>Kenwood, and you can use
>6146 W in place of 6146B, but NOT for a 6146 or 6146A...
>Ray wa7itz
>
>
>Donald E. "Buck" Stiles wrote:
>
>  
>
>>Kenwood listees,
>>
>>I needed replace the tubes and my TS-520.  I have a 6146W tubes available,
>>however, I am concerned that I will not be able to neutralize these tubes.
>>The normal tubes are the 6146/6146A variety.  Has anyone had experience
>>neutralizing the 6146W in the TS-520/TS-520S?
>>
>>Any suggestions appreciated.
>>
>>73 de N8CSP k
>>
>>
>>- - -
>>
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>>
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>
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>
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>
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