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

Sat, 24 Apr 2004 02:28:09 -0400

Larry: 
You must have found some pretty healthy 6146/A/B/W's to have plate
dissipation power of 75 and 90 watts. In my RCA manual for a typical RF
power amplifier running Class C, the max ICAS plate dissipation rating on
the 6146/A/W is 20 watts max. and the 6146B rating is 25 watts. Some of
the earlier Tube manuals initially claimed 35 watts for the "B" but later
versions toned that number down. You're probably referring to typical
max. power output for these various tubes not what the plates will
dissipate per tube.
Anyway, the difference between 150 and 180 watts won't be noticed on the
receiving end, so if you run a pair of 6146/A/W's, set the max. plate
current at around 200 ma. and, if you run a pair of 6146B's, you can run
them a higher current to squeak a little more power out of them, but
who's going to notice. Run them at 200 ma also, and they'll last a long
time.

Pete, WA2CWA

> From: "Larry, K4WLS" <[email protected]>
> Subject: Re: [Kenwood] TS-520/TS-520S Neutralization
> 
> 
> 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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