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

[Ray Friess]

The 6146B was introduced in 1963.  The last RCA
specification sheet on the 6146B was printed in
February 1964!

As for using "matched" pairs:  The manufacturers never
installed "matched" pairs in the radios from the
factory!  Even if you install matched pairs within
several hours of operation the pair will no longer be
"matched" since each tube "ages" at its own rate.

The only place that using "matched" pairs will make
any difference that might even be noticed is when the
tubes are used in push-pull like in audio amplifiers
(and that difference is usually very little when "new"
tubes are installed).  When used in parallel, you
can't tell the difference!  All that "matching" does
is to add to the cost of the tubes.

It will not hurt anything to use matched pair tubes! 
Again, that, in my opinion, only adds to the cost!

As for the 6146W tubes being changed:  I have no idea
as to why the military did not change the
nomenclature.  Unless, this was due to the fact that
RCA originally indicated on the specification sheets
"The 6146B/8298A is unilaterally interchange-able with
the 6146, 6146A, and 8298".  This "fact" was
universally accepted by all of the major amateur radio
equipment manfuacturers.  However, it soon proved not
to be true!

By allowing the production change to be made, and
since RCA had stated that the 6146B was completely
compatible with the earlier versions, the military
would have eliminated the need for stocking two
different part numbers.  The "later" versions were
only an "improved" version and thus wouldn't require a
change in nomenclature.  The "newer" versions could be
used in situations where the equipment had been
designed for the 6146B as well as that equipment that
had been designed for the 6146/6146A.  In my mind,
this makes perfect sense (although the military
doesn't always make sense in some of the things that
they do when it comes to supply!).

If what RCA stated was true, why did Collins Radio
Company have to modify the neutralization circuitry of
those S-Line and KWM-2 series units that had been
previously sold to the United States military
organizations to be able to work with the "new" 6146W
tubes (they had been perfectly compatible with the
"old" 6146W tubes) and why did they change the
circuitry in all new S-Line and KWM-2 series equipment
that was produced?  The answer is obvious!  Their
equipment had to be compatible with the tubes that
were then becoming the "standard" for the military. 
Since the nomenclature on the 6146W tubes had NOT been
changed (for whatever reason it was NOT changed!)
Collins had to make sure that their equipment would
continue to function properly with the latest tubes!

Motorola eventually got "caught up" with the 6146B
problem.  However, this was on the 12 volt heater
equivalents.  In the mid-1970s someone at Motorola got
the "idea" of furnishing the 6883B/8032A/8552 tubes in
place of the older 6883A/8032 tubes that had been used
in the Motrac series equipment since the very first
HHT "A" models came out in 1957.  This was the result
of a new company policy to reduce the number of items
in stock at the Schamburg, Illinois, parts warehouse.

Motorola started shipping the 8552 tubes in boxes
marked 8032.  At that time, I owned the Motorola
reconditioned equipment center for the south-central
United States.  We went through an average of about
100 8032 tubes per week, and, within a week, or two,
we were having to use the 8552 tubes that were sent in
the 8032 boxes.  Within a week of our starting to use
the 8552 tubes in place of the 8032 tubes, we started
getting all sorts of complaints about Motracs being
received with broken tubes!

Prior to that we had not had a single complaint about
broken tubes from shipping.  As a result, I started
checking.  What was happening is that the 8552 tubes,
when used in equipment designed for the 8032 tubes,
were putting out so many parasitic emissions that the
tubes were severely overheating in just the time that
it took to tune up the transmitters and to do the
final tests.  The Motrac is built such that you must
have the final shield (which is also the heatsink for
the driver and final tubes in the unit) in place
before you can tune the radio.  As such, you cannot
see the tube.  Otherwise, we would have immediately
noticed that the tubes were severely overheating.

What was happening is that the tubes became so hot
that the glass envelope was annealed.  The "normal"
shipping "bumps", drops, etc., were such that the
greatly weakened glass was shattered!  Even if the
tubes survived shipping, they were being damaged
within a day, or two, of being installed in the
vehicle and then subjected to the vibrations of the
automobile, truck, etc.

Motorola at first refused to believe me saying that we
must have gotten a "bad" bunch of tubes.  However,
within 2 weeks they got over 1,000 similar complaints
from their field service stations about exactly the
same thing.  The result was that Motorola had to get
in an "emergency" shipment of the 8032 tubes, rebox
all of the 8552 tubes that they had originally boxed
as 8032 tubes, and they had to pay many thousands of
dollars in warranty claims to their service stations. 
All of this because Motorola "believed" RCA when RCA
said that the "B" series of tubes were completely
compatible with the "A" series.

Again, I don't have any problems with installing a
"matched" pair of 6146B tubes when the equipment was
designed for the 6146B.  It adds an unnecessary amount
to the cost, but definitely doesn't hurt anything!  If
the person doesn't want to use 6146W tubes made after
1964, then that doesn't bother me at all even though
the tubes are the same (except the 6146W is "supposed"
to be more "rugged" in its construction - but, the
8298A is also of the same "rugged" constructions and
all RCA 6146B tubes are "cross-branded" with
6146B/8298A and thus should be the same as the later
6146W - this is not true of all other brands, they are
not all "cross-branded"!).

However, I do take "exception" to the statement that
the 6146B was not introduced until 1973!  It was
introduced a full decade before!  In fact, you can
even see the 6146B being "hyped" by RCA in all sorts
of advertisements in the 1964 amateur radio magazines
including the back covers of QST!

Glen, K9STH



Larry, K4WLS wrote:

>Pretty sure the 6146B did not hit the scene until 1973, so do not
>see how 6146W after 1964 can be equivalent to a 6146B.
>
>Don't know where you got your info about the Navy changing specs on the
>6146W beginning in 1963. I was an electronics
>tech in the Navy from 1960 to 1985, I can tell you the specs
>were NEVER changed on the 6146W during that time period.
>Now, got to remember that not only the Navy used that tube
>in old VHF tube gear, the Army and Air Force did as well.
>If the specs had have been changed military supply system
>REQUIRES a change in nomenclature to avoid getting old
>parts mixed up with improved parts. If the specs were changed,
>it would have mostly turned out the tube would have been a
>6146WA
>
>If the 6146W's were the same as, and just as good as, the
>6146B's guarantee you that every commercial company
>that sells ham gear that has a repair facility would have bought
>them all up before you guys bought a 100 or so at the Hamfests
>for about $ 2.00 a tube. Big companies always get the word
>FIRST when the military wants to dump cargo, as the military
>likes to dump it a lot at a time.
>
>Also if you put a new pair in your rig (say your TS-850S) did
>you check the transconductance on one of the old Hickock
>tube testers to see how closely they are matched ??
>
>If you didn't and load up up the rig on CW for 250 mA, one
>tube could be carrying 150 mA (due to higher transconducance)
>while the other is carrying only 100 mA. I have even seen worse
>cases with 6146W's ( one tube carrying 50 mA, while the other
>was straining, crackling, and glowing at 200 mA).
>
>Now for Plate Dissipation. Dissipation is really a poor choice of words for
>this. Thanks to the WA2 who jogged my old brain
>which has not been in too much use lately (technically). Look
>up the word in a dictionary (any), They give as a definition:
>to dispel, disperse, drive away,exhaust, expend, waste, or
>squander.
>
>I had an old EE professor at Clemson who I had in a class
>for RF Power Amplifers. This being back in the mid 1950's,
>electron tube ciurcuits were primarily taught, and we had to
>use slide rules as no electronic calculators. Anyway, everytime
>he referred to the Plate Input Power of a Tube (VP X Ip),
>he referred to it as Plate Dissipation. Well, one day in class,
>I made the mistake of correcting him and telling him that
>plate dissipation was the power that the plate had to expend in
>the form of heat due to the efficiency of the amplifier.  He got
>very hot right quick and told me that plate had to dissipate
>Vp X Ip either in the form of power out, heat from not only the
>plate, but other electrodes as well...........and He finished with
>Mr. Duncan, since the 1st Law of Thermodynamics says that
>energy can neither be created or destroyed, the plate does
>not dissipate, get rid of at any power at all, it merely coverts
>the electrical power to heat energy.
>
>So...he made some good points there even though the definition
>of Plate Dissipation is the plate input power to the tube that doesn't make
>it as outout power so therefore is converted to
>heat energy by the plate. Other losses in an RF Tube Amp as well, such a
>power dissipated [electrical power converted to heat energy :-)  :-)] by
>cathode and screen resistors, I squared R
>losses in tank circuit, etc.
>
>Now, I just pulled a muscle and got a few good sneezes from
>pulling my old 1972  RCA Transmitting Tube Manual from my dusty book shelf.
>It says:
>
>Plate Dissipation for 6146 and 6146A is 25W. 6146B not listed.
>Hmmmmm.....bet it not around yet as I suspected.
>PlateDissipation for 6146W is 25 W.
>
>Pulled down my 1976 RCA Transmitting Tube Maual. It says
>Sneeze, sneeze Oooops !!  SRI:
>6146/6146A Plate Dissipation is 25 W
>6146B Plate Dissipation is 33 W
>6146W Plate Dissipation is 25W  (don't look like upgrade yet).
>
>By the way the 6146B's in parallel in the TS-520 thru 830S
>(which is only Kenwood Rigs I intimate with) the final amp
>runs Class AB1 (the 1 means that the driver does not draw
>any grid current. They run Class AB1 in both CW and SSB.
>Class AB necessary for linear operation of power amp in SSB
>mode.
>
>About the max efficiency you going to get with Class AB
>in parallel is 60 %. So for 180W DC input, you can expect
>to get no more than about 108W output. If the two tubes
>were in push-pull, the maximum theoretical efficiency would
>be 79.8 %. Push-pull tube amps for RF can be a pain.
>
>The old Drake TR-4C:  3 - 6BJ7's (???) in parallel, and it
>operated Class AB2. On voice peaks when operating SSB,
>the Driver would draw some grid current from the finals and
>that is how the ALC was derived. The TR-4C ran Class AB1
>in CW however.
>
>Now you may run 6146W's the rest of your life in your
>Kenwoods and never have a problem, but if I ever get any
>more Kenwood tube gear - it would have to be a matched
>pair of 6146B's in finals for me. Finding a brand new set of RCA
>matched pair 6146B's, would be like Earl Scruggs finding
>a pre WWII Gibson banjo in somebodys attic !!
>
>73,  Larry
>
>
>
>When I was usiung 6146B's in the Kenweood tube gear, I
>always had oretty good luck getting Matched Pairs from
>RF Parts out in CA. Pretty sure they made in Mexico. I
>always looked them over to check for element sagging,
>loose plate caps etc, then checked them for transconductance
>on a Hickock to see if they really matched. I then put them in my
>bench TS-520S with final covers off, and with light off checked]
>for any arcing in tubes or bluish or yellow glow with key down at
>20 Ma.  If all that OK, I made sure I could neuteralize them and get 80W
>output 0n CW on 10M with the test rig. All this using a
>50 Ohm 1 KW Dummy Load.
>
>----------------------------------------------------------------------------
>------------
>
>I think this from Glen Zook is pretty definitive....
>
>Any 6146W tube made after 1964 should be the
>equivalent of the 6146B.  The military changed the
>requirements but did not change the nomenclature.  As
>such, the very old 6146W are the equivalent of the
>6146A but, depending on the individual contract with
>the tube manufacturer, the 6146W tubes started being
>basically an equivalent of the 6146B in mid-1963 and
>all contracts were converted by the end of 1964).
>
>The 2001A is the Japanese equivalent of the 6146B.
>
>Collins had to redesign the neutralization circuitry
>of the 32S-3 series and KWM-2 series to allow the
>military to use the "new" 6146W tubes.  When a 6146B
>or "new" 6146W is installed in the S-Line equipment
>usually the neutralization circuitry "burns up" within
>a very short period of time.  On those units with the
>"improved" neutralization circuitry any of the 6146
>series tubes can be utilized.
>
>Actually, the TS-520 will work with the 6146 / 6146A /
>8298 tube.  But, the power should be reduced to no
>more than 75% of what it will run with the 6146B /
>8298A (and the "new" 6146W) tubes.  He is correct in
>saying that the 2001A is replaced by the 6146B.  If he
>wants to only install 6146B tubes in the units that he
>services, then that is definitely his option.  But, a
>direct substitute for the 6146B is any 6146W with a
>code date after 1964.  In fact, most 6146W tubes with
>a code date of 1964 are going to be the 6146B
>equivalent.  However, there were a very few
>manufacturers that were completing original contracts
>and were still manufacturing 6146A equivalents.
>
>Also, there was a certain manufacturer (I have
>forgotten which one, but it was not a "major" tube
>manufacturer) that produced many thousands of 6146W
>tubes that were not good for anything but audio!  The
>company got paid for the tubes, and then went bankrupt
>before any of them got into service.  When they were
>tried in Collins S-Lines most of the tubes wouldn't
>put out but a few watts on 80 meters and by the time
>they were tried on 10 meters they didn't work at all!
>
>Those tubes sometimes show up in the amateur market.
>Of course they are brand new.  However, unless you are
>going to use them in a modulator (like in the Johnson
>Valiant) they are useless!  Unfortunately, the bulk of
>these tubes go on eBay.  I don't have any manufacturer
>information or even code dates except that I believe
>these were made in the mid-1970s.
>
>Glen, K9STH
>
>--- Ray Friess <rayfri@highstream.net> wrote:
>
>The Kenwood group has been discussing putting 6146W
>tubes in the ts 520, which I have done with no
>problems.  Your discussion on when you can use a W in
>place of a B has been brought up, but this guy
>apparently doesnt believe you..... I think youre
>right, he's wrong.
>
>The TS520's were designed for the S2001A tube. The
>direct replacement for the S2001A is the 6146B. Nuff said.
>
>=====
>Glen, K9STH
>
>Web sites
>
>http://home.comcast.net/~k9sth
>http://home.comcast.net/~zcomco
>
>
>
>
>Clif Holland wrote:
>
>  
>
>>The TS520's were designed for the S2001A tube. The direct replacement for
>>the S2001A is the 6146B. Nuff said.
>>
>>Clif Holland, KA5IPF
>>AVVid
>>Authorized Kenwood and Icom Service Center
>>816 W Shady Grove Rd
>>Irving, TX 75060
>>
>>www.avvid.com
>>
>>1-800-214-5779
>>972-870-0630 (local)
>>
>>
>>----- Original Message ----- 
>>From: "Ray Friess" <rayfri@highstream.net>
>>To: "Larry, K4WLS" <K4WLS@carolina.rr.com>
>>Cc: "Donald E. "Buck" Stiles" <n8csp@triton.net>; <kenwood@mailman.qth.net>
>>Sent: Saturday, April 24, 2004 9:31 AM
>>Subject: Re: [Kenwood] TS-520/TS-520S Neutralization
>>
>>
>>
>>
>>    
>>
>>>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" <rayfri@highstream.net>
>>>>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
>>>>>
>>>>>
>>>>>- - -
>>>>>
>>>>>Your moderator for this list is:
>>>>>Larry Wilson KE1HZ kenwood-owner@mailman.qth.net
>>>>>
>>>>>_______________________________________________
>>>>>Kenwood mailing list
>>>>>Kenwood@mailman.qth.net
>>>>>http://mailman.qth.net/mailman/listinfo/kenwood
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>          
>>>>>
>>>>- - -
>>>>
>>>>Your moderator for this list is:
>>>>Larry Wilson KE1HZ kenwood-owner@mailman.qth.net
>>>>
>>>>_______________________________________________
>>>>Kenwood mailing list
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>>>>http://mailman.qth.net/mailman/listinfo/kenwood
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>        
>>>>
>>>- - -
>>>
>>>Your moderator for this list is:
>>>Larry Wilson KE1HZ kenwood-owner@mailman.qth.net
>>>
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>>>
>>>
>>>
>>>      
>>>
>>
>>
>>
>>
>>    
>>
>
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>
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