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Author Topic: More 811A Modulator Tube Questions  (Read 5137 times)
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W9ZSL
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« on: February 11, 2016, 05:26:34 PM »

I started a new topic because I have a JAN-CD7-811 which might be an "A".  It is made in the USA, seems to be NOS judging from the finned plate which has absolutely no discoloration.  It's labeled Electronic Enterprises, Inc. which seems to be a distributor.  

What is the JAN designation, military?  What does the CD-7 mean?  There are also two small numbers to the left of the info on the base one above the other: 59/42.  I've noticed a lot of variety in the plates.  Rather than buy a pair of tubes for my modulator, I'd rather find a match for the one I have.  Al has answered the one regarding the fins.  Sounds like finding a match might be difficult.  As for the other details about the JAN and so forth, that's more for information.  Bear with me folks, it's been awhile since I tackled a Ham project and need all the help, advise, information I can get.

Any suggestions?

Mike - W9ZSL


* 811.JPG (761.49 KB, 2048x1536 - viewed 329 times.)
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W7TFO
WTF-OVER in 7 land Dennis
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« Reply #1 on: February 11, 2016, 06:58:15 PM »

If you want to move up a bit to a lot tougher (and easier to source) tube,

I'll make you a deal on some 810's & sockets.  They sing as modulators in scores of transmitters.

Run 'em @ 572B values, and they will outlast both of us....

73DG
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W9ZSL
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« Reply #2 on: February 11, 2016, 07:13:54 PM »

Yeah, I'm familiar with them.  Our 1947 vintage Gates transmitter at WOBT here in Rhinelander, WI used 4 of them; 2 for RF and 2 for AF.  That dang thang sounded better than the BC-1T!  Thing is, 810s would work just loafing along.  My mod iron is an S-22 and I'd have to score a filament iron.  a pair of 810s modulating a single 813? Weird!
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WD8KDG
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« Reply #3 on: February 11, 2016, 08:25:36 PM »

JAN= Joint Army Navy

Craig,
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W9ZSL
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« Reply #4 on: February 11, 2016, 08:48:50 PM »

OK...military spec.  Got it!  Thanks!
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WD8KDG
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« Reply #5 on: February 11, 2016, 09:07:53 PM »

Mike,

Looking for somethang to do, walked out to the junk box and peeked. The couple of JAN's that I have are clearly marked 811A.

The 59/42 could be year 1959 and week 42.

Craig,
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Ham radio is now like the surprise in a box of "Cracker-Jacks". There is a new source of RFI every day.
W9ZSL
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« Reply #6 on: February 11, 2016, 09:22:03 PM »

Cool!  I put in a bid on one made by RCA.  I'll see how that turns out in a few minutes.
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w1vtp
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« Reply #7 on: February 11, 2016, 09:42:33 PM »

I started a new topic because I have a JAN-CD7-811 which might be an "A".  It is made in the USA, seems to be NOS judging from the finned plate which has absolutely no discoloration.  It's labeled Electronic Enterprises, Inc. which seems to be a distributor.  

What is the JAN designation, military?  What does the CD-7 mean?  There are also two small numbers to the left of the info on the base one above the other: 59/42.  I've noticed a lot of variety in the plates.  Rather than buy a pair of tubes for my modulator, I'd rather find a match for the one I have.  Al has answered the one regarding the fins.  Sounds like finding a match might be difficult.  As for the other details about the JAN and so forth, that's more for information.  Bear with me folks, it's been awhile since I tackled a Ham project and need all the help, advise, information I can get.

Any suggestions?

Mike - W9ZSL

That tube is clearly an 811A - it has the fins and you can see the top of the "A" on the base

Here's an example of what these tubes are priced at:

http://www.ebay.com/itm/Jan-RCA-811A-Triode-Power-tube-1950s-Brown-Base-Military-Test-Very-Strong-USA-/361483906509?hash=item542a1eadcd:g:F7MAAOSwzhVWqBxY

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W9ZSL
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« Reply #8 on: February 11, 2016, 10:53:47 PM »

Won the bid.  Good to go.  Paid $37 plus $8 shipping.  No excuses now.
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Opcom
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« Reply #9 on: February 12, 2016, 09:54:40 PM »

$37? wow. they are just spares tossed about in old boxes here although not all are new. I better round them up and test them. I thought the Chinese finally made good ones so I had not worried too much, but that might be a mistake.
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W9ZSL
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« Reply #10 on: February 12, 2016, 10:14:41 PM »

Op, this is an RCA with plate fins.  Seller tested it and it came out really high. Seems the tubes with fins are the premium bottles.  I bid on this one because I have another one of the same vintage / configuration.  From what I've learned the Machlett and Taylor brands leave a lot to be desired for longevity.
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