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Title: 4CX1500B Post by: ZL4MD 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 Title: Re: 4CX1500B Post by: w1vtp 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 Title: Re: 4CX1500B Post by: W7TFO on September 11, 2011, 11:18:32 PM John at Econco in Woodland, Ca tests all my power grid tubes for free. :D
I have to pay for shipping both ways. 8) They rate them in terms of "in spec" = good. :D Contact him and set it up 800-532-6626 . 73DG Title: Re: 4CX1500B Post by: flintstone mop 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???? 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 Title: Re: 4CX1500B Post by: WA1GFZ 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. Title: Re: 4CX1500B Post by: ke7trp 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???? 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 Title: Re: 4CX1500B Post by: flintstone mop 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... Title: Re: 4CX1500B Post by: WA1GFZ on September 12, 2011, 09:46:03 PM That was a nice rig.
Title: Re: 4CX1500B Post by: ke7trp 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 Title: Re: 4CX1500B Post by: Opcom 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 Title: Re: 4CX1500B Post by: flintstone mop 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? Clark I would have to PM you about that story................It was a dumb move and I know where it is.C Later.................... |