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Cheapest & Reliable 800 watt PEP Out Amp

Discussion in 'Amateur Radio Amplifiers' started by N8FVJ, Apr 9, 2019.

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  1. N8FVJ

    N8FVJ Ham Member QRZ Page

    IMO the best bargain is a used Ameritron AL-811 three tuber with 572B tube upgrade. Amp is usually $400-$450 and three new 572B are under $200. 80 watts in, 800 watts PEP out on 75 meters, a little less on 10 meters. It will run 1000 PEP out with 100 watts drive on 75 meters, but 800 watts is about the same on the receive end. The extra 572B in the four tube model is a waste of a tube, both the 3 or 4 tube Ameritron have the same strong power supply and three tubes does not need neutralization.
     
  2. N7WR

    N7WR Subscriber QRZ Page

    Sorry but I must disagree. I have owned AL 811's, Al 811H's and AL 80 B amps. There is NO WAY a 3 tube 811 (and the 572B "upgrade" does NOT increase potential power out. The power supply limits the potential) will produce 800 much less 1000 watts. NO WAY. Nor will the 4 tube version (811H). The AL80 B, which in response to the OP's question is the one I recommend, is "rated" at 1000 watts. Realistically running it at 800 watts is what one should do. The 3 tube AL 811H will last at 450-500 watts. Pushing it even to its "rated" 600 watts will shorten tube life. Trying to push it beyond that is foolish.
     
    W2AI likes this.
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The AL-811 power supply is not so robust.

    I have two blown transformers in my garage, after replacing them for people who thought they were.:p

    The AL-80B has a way more serious power supply/transformer. Of course, it's also bigger and heavier.
     
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  4. N8FVJ

    N8FVJ Ham Member QRZ Page

    19 lb AL-811 transformer is not exactly light weight. About same as a Heathkit SB-200. 26lb AL-80B is more heavy duty though.
     
  5. N7WR

    N7WR Subscriber QRZ Page

    Al 811 transformer voltage 1500
    Al 811H " " 1800 (max)
    Al 80B " " 2700

    I rest my case
     
    N2OTG and W2AI like this.
  6. KV6O

    KV6O Ham Member QRZ Page

    The plate transformer alone in my QRO-2500DX weighs over 40lbs, which is more than what many amps weigh.
     
  7. K6BRN

    K6BRN XML Subscriber QRZ Page

    Heck! If ya want the best heavy metal for the least, my buddy has a Henry 2K console, dual 3-500Zs (new) for about the same as an AL-811. Need to pick it up, though. With a truck. Better have a good back.

    THAT one WILL run a kilowatt all day and never break a sweat.
     
    K6LPM likes this.
  8. N8VIL

    N8VIL Ham Member QRZ Page

    I have and use my Al-811 (3 tube) amplifier at 450-500 watts and find it reliable. In my opinion more than that and you are stressing the tubes and power supply. They are a decent amplifier if used conservatively. They were over rated for marketing purposes.
     
    N2OTG and KD2ACO like this.
  9. AA7QQ

    AA7QQ Ham Member QRZ Page

    My 811H does a decent 600 watts or so & I have the 572Bs in it. If I go higher, you can just see some clipping.

    Ed
     
    KD2ACO likes this.
  10. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    That's several pounds of copper and iron... a pretty big difference, actually.
     

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