AL-82 vs AL-1500

Discussion in 'Amateur Radio Amplifiers' started by WL7PM, Feb 13, 2020.

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  1. WL7PM

    WL7PM Ham Member QRZ Page

    Pair of (chinese) 3-500Z are around $450 plus freight...
    3CX1500's out of stock at RFParts, DXEngineering, maybe a few on E-Bay....?
    All three of Ameritrons "Big Boxes" will run 1500 watts continuous.
    Comparing the AL-82 and AL-1500 which would you rather have NEW?
    How about Used if priced reasonable ?
     
  2. AG5CK

    AG5CK Ham Member QRZ Page

    The AL-1500. The 8877 doesn't have to work very hard to make legal limit. It has more gain so your rig can coast along too.

    If/when the 3cx1200a7 in my AL-1200 finally dies it's getting an 8877. I don't mind the 90 second warm up time but it's something to consider.
     
    K0UO likes this.
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Yes, the 8877 is a better tube if you don't mind the warm-up time.

    The Ameritron "big box" amps are all nearly identical except for the tube(s) and evidently the only "weak link" is the HV filter caps are being pushed to their limit, operating and very close to their maximum WVDC ratings under normal operation. I believe Lou W1QJ (maybe with someone else, I forget) sells a "more margin" board with an additional capacitor in series so the caps are all operating well below their max ratings, and if this is still true, that's a change I'd make.

    Bummer to have caps fail, especially if you really want to use the amp and don't have any spares.

    People complain about the audible noise level from all those amps (blower noise) if the blower is run at the full-speed position...but "that's life" and the blower does its job.

    All kinds of tubes may have limited availability in the future, as fewer are manufacturing any and the market has shrunk a lot now that BC transmitters, plasma generators, sputtering machines, MRIs and all the other hardware that used so many of them are going (or have already gone) solid state. 3-500Zs can have limited storage life, so "new old stock" tubes that have been sitting around for years are a roll of the dice -- some may be fine, others may be gassy and there's no way to know by looking at them. 8877s have very long storage life.

    The 8877 in my 6m amp, built in 1985, was a used "pull" from an industrial manufacturer when I bought it for $100 in 1985...it still works fine and still produces 1500W output 35 years later. I think it has a date code of 1981 or something. They last a long time, at least the Eimac ones did.
     
    K0UO likes this.
  4. WO1X

    WO1X Platinum Subscriber Platinum Subscriber QRZ Page

    Any opinions on how long a GU-74B will hold up?
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    No clue.

    However it sure ain't an 8877.:)

    GU-74B data sheet states its max grid dissipation rating is "2 W". Plate dissipation rating is listed as "600 W"

    8877 grid dissipation rating is "25 W". Plate dissipation rating is listed as "1500 W"

    Big difference.
     
    K0UO likes this.
  6. WL7PM

    WL7PM Ham Member QRZ Page

    Am I correct in my understanding the 3CX1500 is long OUT of Production ?
    Was the 3CX1500 ever considered a " Rebuildable" tube ?
    Does anyone know if NEW production AL-1500 are equipped with actual NOS Eimac 8877 ?
     
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    AFAIK Eimac still makes the 3CX1500A7 and the only first-tier authorized distributor is Richardson:
    https://www.relltubes.com/products/Magnetrons/Triode/8877-3CX1500A7.html

    Ameritron still advertises the AL-1500 available with an Eimac tube:
     
    K0UO likes this.
  8. W1QJ

    W1QJ Ham Member QRZ Page

    They are still in production both Eimac and Chinese. A ham never need buy a new one. Many NOS ones NIB floating around along with 100 percent good pulls.
     
    K0UO likes this.
  9. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    This is a photo with an examples of a Ameritron 1500 single 8877 and a special diplomatic unit that has two 8877s, notice the grid current meters differences. The two tube model meter goes to 400 ma, I've never seen it run over a 100ma even on the two tube, for. Safety both units have grid current safety, Shut off.

    On the 2 tube the high voltage power supply is over 4000 Watts at over 2 amps.
    Both amps are using industrial pull out tubes used in MRI's.
    20190226_150856.jpg
     
  10. WL7PM

    WL7PM Ham Member QRZ Page

    Once you figure out which of those 2 amps you want to KEEP.... Sell me the other one !
     
    K0UO likes this.

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