Ameritron AL-811 - no power out - What am I missing?

Discussion in 'Amateur Radio Amplifiers' started by N0AKF, Mar 27, 2015.

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  1. K9STH

    K9STH Platinum Subscriber Platinum Subscriber QRZ Page


    I don't actually own one of the AL-811 or AL-811H amplifiers. But, I have worked on a number of them for others, just like several of those who have already replied. Unfortunately, they are lacking in design and, often, when new, in quality control. Ameritron is owned by mfj and mfj is notorious for quality control problems. To a fairly good extent, they are a "pain in the posterior" to repair. In my opinion, the old Heath SB-200 is a MUCH better amplifier even though it doesn't have the 160-meter band. In fact, the old Heath "Warrior" amplifier, which uses 4-each of the 811A tubes, is a much better amplifier.

    I have an AL-811 sitting on a shelf right now. A client dropped it off for repair at least 2-years ago and hasn't come back for it. It definitely is working, right now. But, I don't have any idea as to how long it will work when put back in service. I have been tempted, at times, to find space on my main operating console and see how long it holds up. However, I definitely will NOT run it to 600-watts output! With 3-each 811A tubes, a peak output of like 450-watts is much more reasonable. I typically run my Heath SB-200 at 600-watts out on 80-meters through 20-meters and reduce the output some what on 15-meters and 10-meters. My main linear is a Henry/Tempo 2001 and I have a Heath Warrior located at my Heath "original" twins operating desk.

    Glen, K9STH
  2. KM5FL

    KM5FL Ham Member QRZ Page

    That statement just proves you don't have a clue..

    First, you need to understand the purpose of this particular forum.. It's an AMPLIFIER TECHNICAL FORUM where those with a TECHNICAL question or some issue with a particular amplifier come seeking a solution. Those in the know such as Carl, Lou, Glen, and others (yes, myself included) can help the OP solve the problem.. If the problem relates to a design flaw, THOSE IN THE KNOW (read that, "those who have experience solving the problem") will let it be known that the problem is due to a specific flaw or weakness. This forum is not a "chit - chat" forum where inexperienced people like you can stir the pot with undocumented "proof" of something to the contrary. You take any 2 of the various contributors to this form and they will have a combined total of 60 - 80 years (or more) of knowledge and experience with amplifiers.. ANY TWO.. It's obvious you aren't either one of them.

    You need to go back home and operate, repair, modify, design, and BUILD amplifiers for a while. When you gain about 20 or so years of amplifier experience, come back here and contribute some of that experience and knowledge... Then we may afford you the respect you have earned..

    Last edited: Apr 1, 2015
  3. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    Yeah, I know... Carl's an interesting character, but we love him anyway...
    My point in several posts on this topic has been, "why do many of these amps work OK and some of them just seem to be dogs?" I don't repair RF amps for a living, but ops in my 'hood drag their BS into my shop because they know I have a good wine collection, tools, and electronics smarts (and my wife is good lookin' and a great cook! That's probably it now that I think about it...). One 811 I've seen painted the inside of the chassis with confetti, and one just needed a new set of tubes and a tune up. Both are owned by good operators with decades more Ham experience than myself, the recording engineer... (AF idiot)

    so... WTF is going on with these things?

    My question to the more knowledgeable repair guys here is if they have noticed a trend of component dress or other specific details that may shed light on why many of these amps work OK and why some of them are Bench Queens.

    I'm on the road still and I just saw Glen's post and that seems to make sense. The 3 tube version is good for 450 watts or so. An op just can't expect 3 811'a to give much more than that. Run 4 811's at 600 watts or so and that's probably enough. Be gentle on the tune ups, etc... and the cheapo 811 amps will probably be OK...

    nuff of my 2 cents...
    Last edited: Apr 1, 2015
  4. KC9VFO

    KC9VFO XML Subscriber QRZ Page

    You are assuming I am looking for your respect...nothing is farther from the truth.

    K9STH is a reasonable man and I will listen to him, I read many of his post. ...Like I said I am appreciative to MFJ/Ameritron and its designer for building a fine amp which works for most of us at an affordable price. All I got to say, The amp works fine.
    Last edited: Apr 1, 2015
  5. KM5FL

    KM5FL Ham Member QRZ Page

    I too read your original post.. "Clicky" huh..... How did you put it, something about joining in???

    With this statement, you called me out:
    I highlighted the important part. I posted a reply, then retracted it.. That's when you took a "second poke at the bear" (me).. Now, before you get in deeper over your head, I suggest you turn loose of this tiger's tail and drop the subject....

  6. KC9VFO

    KC9VFO XML Subscriber QRZ Page

    No, actually I thought you were someone else joining in...been a long day...anyway I am going to go operate on the bands with my Ameritron 811 H for awhile.
  7. KM5FL

    KM5FL Ham Member QRZ Page

    Chris, I think the problems run several layers deep.. The concensus of opinion seems to run along the lines of the AL-811 and it's 4 tube brother is simply too cheaply designed. It appears, that given the poor quality of the available parts, it's just not possible to design an amp of that power range that will retail somewhat south of $1,000. Witness the fact that over the years, Ameritron has made many design changes and modifications to the amp. Then, a few years ago, along comes those cheap Chinese tubes that just add to the failure rate. Another layer is the known fact that MFJ's quality control is hit and miss at best.

    The final straw is that Ameritron advertises the amps' output to be higher than it should be.. Ameritron claims 65% efficiency, but that's not a factor in the formula. Rather, it's arrived at by doing the computations. Compute backwards using Ohm's Law, the readings from an accurate watt meter, and using the maximum plate disapation rating of 65 watts for an 811A tube and see what you come up with for actual "maximum" output power.. The older 811A tubed amplifiers of previous years could make the power they did simply because those old tubes could better handle the "abuse".. At 450 watts output, three 811As are being asked to disapate something around 100 watts each.. That's asking a lot from a Chinese tube of dubious quality.. People who operate these amplifiers at, or at least not to far over those numbers, will probably not have a lot of problems with the amp.

  8. KM1H

    KM1H Ham Member QRZ Page

    A lot of people said the same about the Pinto and Vega also. An econobox of any kind is exactly that and sucks in the bottom dwellers until it receives an early burial.

    No need to worry about that, you dont have any from here. OTOH you make a nice foil for showcasing what many of us feel is wrong with way too many of the current crop of hams...All mouth, limited knowledge. The best part is you dont know when to shut up and keep getting whacked over and over. Even a dumb dog finally wakes up. The ones who come here looking for help with a problem or to increase knowledge get it and turn into decent members of the hobby.

    I and others will continue to bash the AL-811 family and hope others will stop buying them until they are fixed. Meanwhile buy a good used amp or buy less booze and butts to save up for an AL-80B. Very few have room or interest in a 160M antenna anyway so why pay a premium for an amp with it?
  9. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    I could say the same about all those who bash the FL-2100B. Mine is mint, does easy 600W out and didn't break the bank. Sure it might not be the best design, but it works. It's easy to work on and cheap to keep going. The original Cetron's still look new and I baby them, so they should last a while yet. I keep the drive level around 60W and get lots of compliments on the signal, and they don't even know I have an amp on. When and if I can afford a new amp, I think it will be an AL-80B. My main requirements are all band coverage and the ability to do about 800W for RTTY.

    Personally I couldn't care less if the op on the other end is running a $6K Alpha amp or $10K transceiver, but if the bragging helps you sleep at night, have at 'er.
  10. KM1H

    KM1H Ham Member QRZ Page

    There is nothing new in that post as you would find if you went thru weeks, months, or yearsyears of archives on here; these amps have been discussed for ages. At 150W per tube good 811's have always survived. For the AL-811 even the manual is wrong!

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