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All 4-1000 gurus step inside

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

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  1. W4EKY

    W4EKY Ham Member QRZ Page

    In my quest to learn all I can about transmitting tube amplifiers, ive acquired the itch to build a amplifier. Ive researched different types of tubes steel and glass. One that really sticks out is the 4-1000. Google dosent come up with much about 4-1000 except for the Eimac datasheet. I want to hear everyones thoughts and experiences on this particular tube. HV power supplies and fillent supplies are not my concern. I have a pretty good amount of electrical expierence. Explain the requirements and limitations of this tube and whats needed to make it work, such as does it require screen voltage and how is screen voltage obtained, this will be a single band amplifier. Either 10m or 160m my Henry 2KD, Drake L4B dont have 160m and my Al-82 dosent do very good on 10m..

    Thanks 73's W4EKY Chase E. Ousley
  2. W4EKY

    W4EKY Ham Member QRZ Page

    If the 4-1000 is grid driven, there is no need for a screen supply.. correct?
  3. K9STH

    K9STH Ham Member QRZ Page

    I suggest building the single band linear for 160-meters because when 10-meters is open, you don't need anywhere near as much power as you can get out of the 4-1000.

    However, unless you already have the tube in hand, there are definitely better choices of tubes that are much less expensive and easier to use. If you want full legal power, the Russian GS-31b or GS-35b are excellent choices. The difference, between the types, is the heat sink and, therefore, the maximum power with the GS-35b being higher powered. But, the GS-31b can do full legal output and they are running right at $100.00 up including shipping from Europe. The GS-35b tubes are running about $150.00 up including shipping from Europe.

    I built a single band 160-meter amplifier that uses the smaller GI-7bT tubes that runs about 850-watts out with the puny power supply that I am using. With a heavier supply, the amplifier can do over 1000-watts output.

    I have several GS-31b and several GI-7bT tubes that I am planning on using for linear amplifier for various bands from 160-meters up to 70cm.

    Glen, K9STH
    KK5JY and N2EY like this.
  4. W4EKY

    W4EKY Ham Member QRZ Page

    im sorry, what i really meant is that if the 4-1000 tube is grounded grid and cathode driven, screen voltage and supply are not needed correct?
  5. KI6LZ

    KI6LZ Ham Member QRZ Page

    All of us teen hams built them grounded grid, lots of plate voltage and lots of drive. They were pretty cheap back then sold at most hamfests as pull outs.
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I've built amps using 4-1000As and still have them. One was the subject of a feature magazine article I wrote which was published in the July 1985 issue of 73 magazine called "Build the Block Buster" and it was on the cover of CQ magazine as well.

    The original construction article contains many photographs and complete schematic diagrams with parts lists.

    Mine are grid-driven and of course do have separate grid bias and screen supplies, as shown. I derived screen voltage using a separate transformer, bridge and filter system and it's about 600Vdc; the B+ is 4200Vdc; the bias supply is also separate (all on the same power supply chassis) and provides cutoff bias in standby and regulated adjustable bias for operating in AB1. With 20W drive it makes 1500W output power, any mode.

    The tube wasn't designed for grounded grid operation, although surely a lot of hams ran them that way. That's much simpler, as it reduces power supply complexity -- but the tube is hard to drive in GG and even with a good tuned input network takes about 150-175W to drive it to serious power, so the typical modern "100W solid state" transceiver cannot drive the tube to legal limit output. Some old tube-type transceivers could.

    Grid driven in AB1, even a little 5W rig like the FT-817 can drive the amp to about 400W output power.

    This tube runs best with a lot of B+. My supply delivers about 4400Vdc key-up and 4200Vdc key-down at 750 mA. Don't expect the kind of gain or output numbers quoted above with lower voltages, although even at 3 kV it's still a pretty usable tube. Note that Ig2 is related to B+ and if you run lower HV, you need to reduce screen voltage as well to prevent excessive screen current.
    KK5JY, KK4RSV, AF6LJ and 2 others like this.
  7. KU3X

    KU3X Ham Member QRZ Page

    My 4-1000 runs 3900 volts key down and with 70 watts of drive I can easily get legal limit out on all band. I think it takes a tad more drive on 10 meters if I remember correctly.
    Mine is grounded grid and it works on all bands from 10 to 160 meters. I do have tuned inputs. I can send you the complete schematic with a detailed parts list. In the BOM is
    the needed information for winding your own plate choke.

    A picture of the amp is here:

    I have numerous spare tubes and all have tested to be within + / - 100 watts output with the same amout of drive and the same power supply.

    At 100 watts of dive on a power supply that puts out 2800 volts key down, I would get 1200 watts out.

    If you are going to build an amp and have never done it before, get hold of one of Bill Orr's Radio Handbooks.
    Building HF amps is not as simple as point to point wiring. There's a lot that comes into play as far as layout and RF lead lengths.
    If I can do it, you can do it. But read Bill Orr's book first. The ARRL handbook is also pretty good. Pay strict attention to the tuned input design. It is a key component when it come to
    efficiency. Do it wrong and the efficiency will suffer.
    The 4-1000 in GG is a pretty good amp. One article in an old QST refered to the the 4-1000 being built like a Mack Truck. It really is.

    If you can get legal limit out with under 100 watts, I don't see the need to build a 4-1000 as Grid Driven. I did consider building one grid driven only because I could use my KX3 to drive
    it and get legal limit out.
    Barry, KU3X
    Last edited: Jan 16, 2017
    AI6KX, K8PG, KK4RSV and 2 others like this.
  8. W4EKY

    W4EKY Ham Member QRZ Page

    Thanks for your information. Would you please email me the schematics and parts list that you have? also interested in one of your spare tubes.
  9. W4EKY

    W4EKY Ham Member QRZ Page

    I have repaired numerous 3-500z amps. Everything from Drake l4bs and sb-220 and built several HV power supplies for various projects at work, but at a larger magnitude. As far as similarity, isnt the concept and circuitry pretty much the same as a GG 3-500z..
  10. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    Hmmm. I thought you were contemplating building a twin 3-500Z linear.

    Last edited: Jan 16, 2017

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