Ameritron AL-811 & AL-80B - Best Value Amplifiers

Discussion in 'Amateur Radio Equipment Reviews' started by N8FVJ, Oct 9, 2019.

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  1. N8FVJ

    N8FVJ Ham Member QRZ Page

    There has not been a post since 2007 on the AL-811. So, I will review what I consider the best two HF amplifier used bargains. New is not necessary and is expensive. First, either amplifier does not require rebuilding replacing the power supply capacitors or out of tolerance resistors. Keying is 12 volts at 100ma, no high voltage interface required.

    The AL-811 can be purchased for around $450 used. This amplifier has the same power supply as the AL-811H with four 811A tubes. Bands are 160 meters to 10 meters with a tuned input. This amplifier is very reliable giving service day after day. The issue with the AL-811 is the weak tubes. You cannot safely get more than 450 watts PEP out with three 811A tubes. The only reason I list this amplifier is it can be upgraded with three 572B tubes. Four 572B tubes in the AL-811H is a waste of money, does not produce any more power and requires neutralization unlike the three tube AL-811. The 19lb power transformer is powerful enough to support 800 watts PEP out with 572B tubes reliably year after year. Three tubes is about $150 and these are new. The 811A tubes in a used amp may be soft anyways. For $600 with new 572B tubes + shipping costs, it is a lot of power out for the money.

    For about $800 used, you may want to consider the Ameritron AL-80B. This amp is 160 thru 10 meters with a tuned input and same low voltage relay switching as the AL-811 amplifier. These amps are new enough that rebuilding is not needed. The AL-80A & Heathkit SB-1000 is at times a little less expensive vs the AL-80B and about the same as the AL-80B. Avoid the AL-80 as it is a different amp and not reliable. The AL-80B has a huge power transformer weighing 26lbs. It will produce 1000 watts PEP out. Using a single 3-500Z, a replacement tube costs $200. The 3-500Z tube is very heavy duty with a 500 watt plate dissipation rating. Three 572B are rated 480 watts plate dissipation, but I consider the 572B closer to about 130 watts plate dissipation per tube.

    In my opinion either of these amplifiers will produce within 1 S unit of a legal limit output HF amp and the replacement tubes are not too expensive. Some new replacement ceramic tubes can cost as much as these amplifiers. I would not own an AL-811 without the 572B tubes though. You should enjoy years of trouble free service at a reasonable cost. Failures are very uncommon in either amplifier.
     
  2. W5LZ

    W5LZ Ham Member QRZ Page

    "I would not own an AL-811 without the 572B tubes though. You should enjoy years of trouble free service at a reasonable cost. Failures are very uncommon in either amplifier."
    Then I would suggest the AL-572 amplifier. To substitute a 572 for an 811 requires making a couple modification to that AL-811. You are right though. Those amplifiers seldom make a mistake, the operator does...
     
    W1TRY and K0UO like this.
  3. N8FVJ

    N8FVJ Ham Member QRZ Page

     
  4. K0UO

    K0UO Subscriber QRZ Page

    I think you're going to see a lot of tube type amplifiers selling at a much lower price.
    Just like what has happened to transceivers since the 7300 has came out prices have Fallen on good used equipment.

    Just about everybody I talk to is using a new transistor HF amp or thinking about buying one. Which eventually means all those tube amp that many of us have, (a lot of guys have two or three or more) are going to be coming down in price and become more affordable.
     
  5. N8FVJ

    N8FVJ Ham Member QRZ Page

    That is good news regarding tube amplifiers. The reason I do not care for SS amps is I use a myantennas 8010 and do not need a tuner as the antenna is 2 to 1 or less SWR on all bands. SS tuners without a built-in tuner will not operate into a 2 to 1 SWR and cost a fortune. I saved around $300 less the antenna tuner making the amplifier 1/2 price to speak.
     
    K0UO likes this.
  6. N8FVJ

    N8FVJ Ham Member QRZ Page

    BTW- I did not modify my AL-811 with 572B tubes. Works perfect and the tubes operate within tube specifications.
     
  7. W5LZ

    W5LZ Ham Member QRZ Page

    An AL-811 was the first 'new' amplifier I had. It was serial number '13', honest, not a joke. Even with my less than adequate knowledge of amplifiers I can't say it was the best thing ever made (a number of subsequent changes were made by Ameritron). The second one was better in a number of ways. I can tear up anything and after some of the modifications I made to it, it followed the first one into the 'surplus' pile. Later got an AL-80A. Sure, it had a few qwerks. but a very nice amplifier over all. Best advice I can think of is buy bigger and run smaller. Things last a lot longer that way. After getting to something around 500 - 800 watts, there's no significant change in your signal strength till you at -least- triple the power output.
     
  8. N8FVJ

    N8FVJ Ham Member QRZ Page

    There is a limit of reliability benefits using a powerful amp at say 3/4 power vs maximum power out. If the transformer and tubes can comfortably perform the task, who cares. Three Cetron 572B tubes in an AL-811 at 500 to 800 watts PEP out is going to take the Cetron tubes from a 25 years life to 23 years? The transformer is simply unaffected at either 500 or 800 watts out. If it was a 14lb vs 19lb transformer, that would raise a question at 800 watts PEP out.

    MFJ designed a lot of transformer capacity in the AL-811 amplifier. Interesting the AL-572 amp uses a 21lb transformer for 1300 watts PEP out. It is definitely overloaded with using I guess M19 laminations in both transformers. If the very unlikely higher efficient M6 laminations were used in the AL-572 I would have to rethink my calculations.
     
    Last edited: Oct 13, 2019
  9. AC9VT

    AC9VT Ham Member QRZ Page

    I picked up a Al-572 today that looks good, might test run it tomorrow, pending a new short run of a 220 circuit into the shack but a pretty easy job. Indications from inspection and cleaning are promising. Seems all original other than 10 meter wire clip and a kinda tired looking set of russian 572's. I am sure it could benefit from a new set of 572b's and if I need to I will and be still only have 811h type money in it. If it works but a bit soft i will just run it for now, only looking for 600 ish watts for now anyway. Wish me luck. P.S. who is selling the prefered choice in new 572B tubes if I were to need to order a set next week. ???
     
  10. N8FVJ

    N8FVJ Ham Member QRZ Page

    Only one manufacture makes 572B. That is Shuguang of China. RF Parts in the USA with their label is the same tube. Now, the Chinese 572B has been constantly improved and likely in the last year is up to date. So, ask the year of manufacture. China sells Shuguang 572B tubes as low as $44 each on eBay- about 3 weeks delivery to USA. RF Parts in the USA sells the same 572B tube for $89.
    If you want only 600 watts PEP out, there is a high voltage tap in the AL-572 that lowers voltage for using 811A tubes. Four 811A lasts a long time used at 600 watts out, but not at 800 watts out. The 811A sells for $34 from RF Parts. A Pvsane 811A from China is $21 on eBay, but I do not know the year of manufacture and if a Shuguang manufacture tube. The best deal and known to last 20 years is the Russian G-811. These tubes are $21.59 each in lots of four from Ukraine on eBay. The AL-572 is rated at 1300 watts PEP out, I would operate the amp at 1000 watts PEP out with 572B tubes due to the weak 21lb transformer. The AL-80B has a 26lb transformer and rated at 1000 watts PEP out- go figure.

    BTW- 600 watts PEP is about equal to 400 watts CW. So, do not operate four 811A above 400 watts CW. RTTY is de-rated more than CW too.
     
    Last edited: Oct 13, 2019

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