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Author Topic: Newbie ordered 6146W tubes for my Kenwood TS-820 - now what?  (Read 8157 times)
KK4RXN
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Posts: 110




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« on: July 16, 2013, 08:49:42 AM »

I've had a great time learning a lot about my Kenwood TS-820 over the last month. A friend of mine helped me with taking it apart and testing the tubes, and after cleaning it seems to be working really well on transmit and receive. I figured I'd renew it and get new tubes.

I bought 2 non-matching GE 6146W and 12BY7A-JAN tubes from Surplus Sales (http://www.surplussales.com/Tubes-Sock-Acc/TubeSpecials.html).

I'm sure I can't just plug these 3 new tubes in and go, and I'm pretty new to this rig... and in reading about neutralizing the finals, etc., I'm getting a little intimidated. I will probably need to go back to my friend to see if he can help me out, but can someone shed some light on where I need to go from here?

Thanks to everybody that is always so helpful.

Barry
KK4RXN
Jeremiah 29:11-13 / John 3:16
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Barry
KK4RXN
Jeremiah 29:11-13 / John 3:16
AA4PB
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« Reply #1 on: July 16, 2013, 09:48:52 AM »

If its working really well then why change the tubes? If it ain't broke, don't fix it  Cheesy  I'd put the new tubes away and save them for some future time when a tube may fail.
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KK4RXN
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« Reply #2 on: July 16, 2013, 09:50:24 AM »

Thinking about getting a little more power, but yes, I may save them for a little while.

Barry
KK4RXN
Jeremiah 29:11-13 / John 3:16
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Barry
KK4RXN
Jeremiah 29:11-13 / John 3:16
KK4RXN
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Posts: 110




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« Reply #3 on: July 16, 2013, 09:57:04 AM »

What I may do is replace the driver tube and wait on the finals. That requires no neutralizing, right?

Barry
KK4RXN
Jeremiah 29:11-13 / John 3:16
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Barry
KK4RXN
Jeremiah 29:11-13 / John 3:16
G3RZP
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Posts: 4391




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« Reply #4 on: July 16, 2013, 09:59:06 AM »

If the originals are 6146B, you can't push a 6146W to the same plate dissipation. A 6146W is a mechanically ruggedized 6146A with 25 watts dissipation as against the 6146B with its 35 watts dissipation.

Otherwise, follow AA4PB's advice.
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AA4PB
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« Reply #5 on: July 16, 2013, 10:01:31 AM »

Have you checked the power output - is it low? A few watts isn't going to make any performance difference.

I've never re-tubed a TS-820 but I have changed 6146's in a number of other transceivers in past years and never found that I needed to re-neutralize any of them.
 
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KG6YV
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Posts: 506




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« Reply #6 on: July 16, 2013, 01:50:13 PM »

I re-tubed my 2820S a couple of years ago with 6146W's... Yest they don't have 35W of plate dissipation but at 100W output who cares. 

1.  Check the values of the two cathode resistors for the finals under the PC board.  If they are still the correct value replace the tubes and neutralize, if not replace the resistors.
2. I "cold-neutralize" all tube finals (6146 and sweep tubes).  I disconnect the screen voltage from the tubes and tape the wires.  Then I peak the preselector to tune the driver on whatever band the manual says.  I measure the output at the antenna plug and tune the neutralizing cap for minimum. 
Voila, you are neutralized and no need to "putz" with dipping the finals or anything.

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KE3WD
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« Reply #7 on: July 16, 2013, 02:25:18 PM »

My advice is to keep all new tubes for when you actually need them and enjoy running the rig with the tubes that are in it and working now. 

"If it works, don't fix it!"  Is not snark, it is really good advice. 


73
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KE4DRN
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Posts: 3714




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« Reply #8 on: July 19, 2013, 02:39:00 PM »

hi,

Here is good info Barry got from the TS-5xx 8xx hybrid group on Yahoo,
the messages are open to the public.

http://groups.yahoo.com/group/TS-520_820_530_830/message/43356

Join other TS-5xx and 8xx hybrid fans, over 3,400 members worldwide.

73 james
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W6EM
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Posts: 727




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« Reply #9 on: July 19, 2013, 07:08:21 PM »

I remember when that Surplus Sales guy outbid me on the lot of 200+ of those from DoD about 15 years ago.  I think my high bid was 50 cents under his.  He paid about $2.00 apiece for the lot of them.  Of course, he had to have them packed and shipped to Omaha.......

So, when he asks a high price for them, keep that in mind.  In those days, auctions were run by DoD and were sealed bid.  Probably 1950's manufacture.
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KC4MOP
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Posts: 729




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« Reply #10 on: July 20, 2013, 07:38:09 AM »

If the CW mode or tune-up power is steady and not sagging; then leave the originals in there.
The manual comes in handy. Neutralization may be needed. The 6146B might be more susceptible to parasitics than the 6146 or 6146A.
I get really anal about having a manual (TECH manual) when trying to maintain a piece of electronic stuff.
Fred
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KE4DRN
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« Reply #11 on: July 20, 2013, 08:06:52 PM »

hi,

the GE JAN tubes drive and finals are circa 1985, made in usa.
from surplus sales, look for tube specials.

73 james
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G3RZP
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« Reply #12 on: July 21, 2013, 03:00:04 AM »

Don't forget they have a lower plate dissipation than 6146Bs.
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NO2A
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Posts: 758




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« Reply #13 on: August 05, 2013, 07:18:26 PM »

Be tender with the bandswitch in those rigs. I have the TS-830S,and sometimes the contacts don`t make contact! You`ll know if your receive suddenly goes south. I hate manual bandswitches for that reason. I`m glad you got the driver tube,as they can fail before the finals do.
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K8AXW
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« Reply #14 on: August 05, 2013, 09:49:46 PM »

I agree with the others...... measure the power output and if it's around 100W, leave it alone.  My TS-830S is over 30 years old and still running the original tubes!!
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