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4CX1500B




 
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Author Topic: 4CX1500B  (Read 6641 times)
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ZL4MD
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« on: September 11, 2011, 07:38:56 PM »

 I have three donated 4CX1500B "pulls". These were extracted from a military transmitter and were pulled, I gather, because of tube hours rather than any failures. Also, the "puller" assured me that one of the tubes was quite young in terms of hours! [one is more shiny and the ceramic is clean and white].

As I don't want to put a lot of effort into building an amplifier and then find they are all duds, are there any simple tests that I can set up to confirm that there is some useful life left ?

My testing to date has been to confirm that the filaments are intact and that there are no internal shorts. Also, I have set a socket on an airtight box and applied a generous airflow [nearly an inch on the water manometer]. I then gently applied rated heater voltage to each tube in turn - all showed normal heater currents, consistent with Eimac specifications. My problem is what to do next ? Perhaps, apply some grid bias, plate volts and screen volts and see what plate current flows ?

If I have some useful tubes, I would also like to go the AM linear way but the Eimac data sheets only cover SSB operation.

All suggestions would be appreciated.

73,       Kevin    ZL4MD
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w1vtp
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« Reply #1 on: September 11, 2011, 08:32:38 PM »

Great tube.  Just keep in mind that the control grid has a dissapation of 1 watt.  You would probably want to put in some sort of overload circuit that acts fast.

Al
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W7TFO
WTF-OVER in 7 land Dennis
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IN A TRIODE NO ONE CAN HEAR YOU SCREEN


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« Reply #2 on: September 11, 2011, 11:18:32 PM »

John at Econco in Woodland, Ca tests all my power grid tubes for free. Cheesy 

I have to pay for shipping both ways. Cool

They rate them in terms of "in spec" = good. Cheesy

Contact him and set it up 800-532-6626 .

73DG

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Just pacing the Farady cage...
flintstone mop
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« Reply #3 on: September 12, 2011, 06:46:26 AM »

Hi Kevin
I hope someone here can give you advice how to do this at home with some simple set-up. I don't think you want to ship the tubes from your QTH and hope they are not damaged just for a test.
I read that you at least have a socket and air. That's a beginning...
That is a helluva tube.........I had a plate modulated TX, not built by me, that screamed in Class C 2500W out at 3500VDC at 5 amps...The power supply was common to the modulator deck, which was a pair of 4CX1200A's.......I'm guessing you are going to make a leanyear?Huh
I will look around the shack...I might have the original schematic for the class C design...I could scan and post here as a PDF
Fred
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Fred KC4MOP
WA1GFZ
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« Reply #4 on: September 12, 2011, 12:43:08 PM »

drive the grid with a 50 ohm resistor load. normal grid and screen voltages.
Alpha made an amp with a pair of 4CX800s that was grid driven. You can download the manual.
Or duplicate the collins 30S1 circuit. Good tube.
Fred I think you had the 4CX1500A.
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ke7trp
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« Reply #5 on: September 12, 2011, 12:50:11 PM »

Fred, Do yo have pictures of that beast???

Hi Kevin
I hope someone here can give you advice how to do this at home with some simple set-up. I don't think you want to ship the tubes from your QTH and hope they are not damaged just for a test.
I read that you at least have a socket and air. That's a beginning...
That is a helluva tube.........I had a plate modulated TX, not built by me, that screamed in Class C 2500W out at 3500VDC at 5 amps...The power supply was common to the modulator deck, which was a pair of 4CX1200A's.......I'm guessing you are going to make a leanyear?Huh
I will look around the shack...I might have the original schematic for the class C design...I could scan and post here as a PDF
Fred
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flintstone mop
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« Reply #6 on: September 12, 2011, 08:28:04 PM »

Yes Pete
it was the 4CX1500A which is a different filament voltage...

Hi Clark I have some links to the AMWINDOW dayzzzzz

http://www.amwindow.org/pix/htm/mop981.htm
Around the middle of the page is "see more of the transmitter" several more pages of the innards...........It was a helluva box........I did dumb move...Sold it and it hasn't been on the air since.......possibly 10 years...
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Fred KC4MOP
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« Reply #7 on: September 12, 2011, 09:46:03 PM »

That was a nice rig.
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ke7trp
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« Reply #8 on: September 12, 2011, 11:04:52 PM »

That really was a Kick ass Rig there Fred. Where is it?  Why not try to track it down?
C
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Patrick J. / KD5OEI
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« Reply #9 on: September 13, 2011, 12:41:19 AM »

There are a few good pointers to 4CX1500 amps in this BB. I'd asked about a 4CX1000 for a friend, but the several examples offered were of the 1500.
http://amfone.net/Amforum/index.php?topic=26574.0
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Radio Candelstein - Flagship Station of the NRK Radio Network.
flintstone mop
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« Reply #10 on: September 13, 2011, 06:51:54 AM »

That really was a Kick ass Rig there Fred. Where is it?  Why not try to track it down?
C
Clark I would have to PM you about that story................It was a dumb move and I know where it is.
Later....................
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Fred KC4MOP
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