[Kenwood] TS-520/TS-520S Neutralization
Larry, K4WLS
[email protected]
Sun, 25 Apr 2004 00:24:26 -0400
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.
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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 <[email protected]> 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" <[email protected]>
>To: "Larry, K4WLS" <[email protected]>
>Cc: "Donald E. "Buck" Stiles" <[email protected]>; <[email protected]>
>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" <[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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>>>>Larry Wilson KE1HZ [email protected]
>>>>
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>>>>
>>>>
>>>>
>>>>
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