All 4-1000 gurus step inside

Discussion in 'Amateur Radio Amplifiers' started by W4EKY, Jan 16, 2017.

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  1. K0RGR

    K0RGR Premium Subscriber QRZ Page

    My late father built a 4-1000A linear, grid driven, that was by far the most rugged one I ever used. It would do full legal power without breaking a sweat. It's still sitting in a garage in California, and every time I go there with my pickup truck, my brother tries to get me to take it home. Unfortunately, I'm afraid the power transformer for it might exceed the GVWR of my Tundra, and I don't have a forklift to handle it - it's an old 'pole pig' with a huge iron core that is marked '1919'. It looks like something out of Frankenstein's laboratory.

    I saw a design for a solid state switching power supply that ought to provide the HV for such a device, and probably weighs 1/100th as much as Dad's old supply.

    Someone I knew built a 4-1000A amp as his senior project in the EE program at San Jose State. When we fired it up for the first time, it started to self-oscillate at very close to 27 MHz.. The wiring error was soon corrected.
    WA7PRC and AF6LJ like this.
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I'd think a conventional 1/2-ton pickup could handle it. Does it really weigh 1000 lbs? That's a bit over the top.

    Even old pole pigs were about 250 lbs or so. I'd think the "big problem" would be onloading/offloading. Might take four strong guys or a forklift. I don't own a forklift either, but they can be rented. I have a pallet jack which can handle 2000 lbs, but not a substitute for a forklift that can raise up to the bed of a pickup.
    N2EY likes this.
  3. KH2G

    KH2G Guest

  4. W4EKY

    W4EKY Ham Member QRZ Page

    Thanks for everyones replies. First off I wanna say that I am probably going in neck deep on this project, but i have made my mind up that I'm gonna attempt to build a 4-1000 amplifier. With the grace of god and help from all you experts on here, its not going to be easy but definitely a learning expierence. I have a pretty good amount of electrical expierence in the past years with three phase high medium and low voltages. From 440-12,470v.I have located an old Gates 2.5k FM transmitter cabinet. Everything is still in the cabinet except for the plate transformer of the origonal 5cxxxx tube. Nothing in there but maybe some wiring will be reusable for my build. It will be a very nice cabinet when i refinish the outside and duild the RF, tank and transformer decks. After posting an ad on QTH, a fellow ham emailed me. He has pretty much everything to build a 4-1000 amp. Not only that, he has the right stuff to build a dual 4-1000. The transformer came out of an old AM Radio transmitter. 240v primary and secondary taps are 2900, 3500 and 4000 @ 1.75 amps ccs. The transformer ran 2 4-1000's. He has a B&W 850A tank coil 10-80m thats brand new. Powerstat 240v big variac 0-280v at 18 amp. Two filament transformers and chokes along with a smaller variac to keep the filament touched up. Eimac chimney and socket. Bleeder resistors 225w 100k. Theres much more we havent really discussed and we will go through when i get to his qth. Im gonna have quiet a few questions. So we may as well start somewhere.

    1. The two filament transformers are different brands. One is a stancor and I cannot remember the other brand. But both are 7.5v @ 25A. Im not so sure about running two different filament transformers in one amp. Also i know the importance of keeping balance on the two 120v lines coming into the amp. Should I not buy the two different transformers and have a new 40-50 amp transformer wound or if it would be ok to run them what would be the best route to wire the primaries of them along with the plate transformer. The transmitter cabinet has two sets of push button switches that will be controlling two double pole contactors for the plate and filament transformers.
    AC8AC likes this.
  5. AC8AC

    AC8AC Ham Member QRZ Page

    I rarely get lucky enough to find pulls in my area . once and a wile I find stuff miss labeled on ebay and catch a deal that's how I picked up a 3cpx1500 for $75 been trying to find a spare sense . that amplifier works great BUT no tube glow so my al82 gets the most use

    the 4-1000 amplifier always peaked my want list sense a young man had a ham in the neighborhood who used one as a lamp on his desk I would spend hours talking to him about electronics . that turned into me listening with a receiver and thought wow these guys are everywhere 20 years and 3 kids later I became a ham myself . but face of radio has changed

    still my fascination with it has not . to this day I don't remember his call but he planted a seed based off that tube glowing on his bench and his willingness to listen to all my dumb questions
  6. W4EKY

    W4EKY Ham Member QRZ Page

    Here is the old cabinet. It will make a nice piece when I restore it with a whole new face and a paint job.

    Attached Files:

    KM1H likes this.
  7. W4EKY

    W4EKY Ham Member QRZ Page

    Two separate 240vac primary transformers, the primaries will wire up in series with. 120v line on one leg of each transformer? Or parallel?
    Last edited: Jan 21, 2017
  8. W4EKY

    W4EKY Ham Member QRZ Page

    Disregard the last post about the filament transformers.

    The two filament transformers are different make, same ratings with 240v primaries dual primaries.. go with another bigger single transformer or can i use these two. Also need a diagram on wiring the primaries.
    Last edited: Jan 21, 2017
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    What do you mean by dual primaries? Often this means two 120V primaries you can wire in parallel to feed them from 120V or in series to feed them from 240V (for each transformer).

    I wouldn't worry about two separate filament transformers, the only important thing is both cathodes need to be about the same temperature; doesn't matter where the power comes from.

    If this will be GG, it will take a lot of power to drive two 4-1000As. But if they're grid-driven, it won't take much. 40W drive should produce 3kW output power or so.:p
  10. W4EKY

    W4EKY Ham Member QRZ Page


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