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. KO6WB

    KO6WB Premium Subscriber QRZ Page

    Have you opened the amplifier cover and made sure the tubes are all seated and the plate caps are connected?

    At 50 watts the grid current should be over 100 mA and the plate current around 450-550 mA.

    On the TS-590, look at the power output while trying to drive the amplifier. It should remain at the level you previously set it to when operating in STBY.

    If the power output has decreased then look at the SWR function on the 590. It should be below 1.2:1 or so. If not, then you have an input problem.
    The setting and menu selections you have for the 590 are spot on. So, there's no problem with the 590.

    Hope this helps
    73
    Gary

    P.S. If you are unfamiliar with high voltage circuits then make sure you have help from someone that has and never work alone. There's a goob more to this. So, be very careful. One slip and you'd never have another bad day to worry about.
     
    Last edited: Mar 28, 2015
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If the plate current is zero when driven, the tubes aren't connected. The idling current alone, without any RF drive at all, once the amplifier is keyed, cannot be zero.
     
  3. W9JEF

    W9JEF Platinum Subscriber Platinum Subscriber QRZ Page

    Full plate voltage reading, only 20 mA grid current, no plate current...sounds like the 811-A's are biased to cutoff as in standby.

    I would check the operation of Ry 1--coil should show voltage, and it should close on transmit. BE CAREFUL!!!

    [​IMG]
     
    Last edited: Mar 28, 2015
  4. N0AKF

    N0AKF Ham Member QRZ Page

    Well I was going to check it out after work last night - went to power it on and no power at all to the amp. No meter, no fan nothing. Both fuses ceck good with a multi meter. (o.oL. So I have contacted the vendor - it has a 30 day warranty. I have boght numerous items from them before and they are a top notch dealer so I know they will take care of it. THANK YOU all for the advice!
     
  5. KJ4UQT

    KJ4UQT Ham Member QRZ Page

    This may very well be a blessing in disguise.

    I wanted to say this when I read your first post.

    But, the AL-811 amp was already there.


    Save a few more dollars and move to a AL-80B.

    Best of luck with whatever you decide.
     
  6. KM5FL

    KM5FL Ham Member QRZ Page

    You've already been made aware of the woes of owning
    an AL-811/H amplifier. I alluded to that on your other thread
    concerning this very amp.. The poor tube quailty and other
    inherent problems have been discussed numerous times in numerous
    threads in this forum.. Take the warnings and problems you're
    experiencing with this newly purchased AL-811 as a "sign from above"..
    If the dealer is as good as you say, return the amp, get a refund
    and be done with it.. Your very best bet is an AL-80B, it's hard to
    beat for the bux.. It will easily run 600 - 700 watts all day
    long and never break a sweat..

    KM5FL
     
  7. N0AKF

    N0AKF Ham Member QRZ Page

    Your right, I should have done more research :( I read the reviews at eham, and was aware of the MFJ/etc woes, but thought maybe buying used from a dealer someone else would have found the bugs and they were taken care of. The dealer is at a hamfest this weekend, so will see Monday. They are good folks so I have no doubt they will take care of it.
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I agree AL-80B is a solid amp and nobody has any problems with them. I have one myself which is rock-solid for 14 years now.

    AL-811, not so much.
     
  9. KM5FL

    KM5FL Ham Member QRZ Page

    Don't take this as me picking on you or singling you out.. Believe
    me that's the last thing on my mind. You're not the first person with
    the belief that "the bugs have been worked out.." The amp in it's
    basic design has some "bugs", some are "field correctable", but most
    are inherent to the design and can't be readily corrected.. The quality
    seems to be hit and miss.. Getting your hands on a good AL-811/H, be
    it new or used, is a crap shoot at best.. A gamble I'm not willing to take.

    Today's 811A tubes all come from China. And the Chinese, for what
    ever reason, just absolutely cannot manufacture a quality tube.
    They're all crap to begin with, and when these problematic tubes are
    Installed in a crappy designed amplifier, the sparks start flying..
    And the problem is really amplified (pun intended), when the owner
    believes those inflated output figures and trys to run the amp at
    those outputs.. The tubes literally melt down..


    KM5FL
     
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    IMO Ameritron has done an amazing job of trying various technical patches in the AL-811. But 811As are a 70-plus year old design and while they were pretty good when American made and RCA actually agreed Collins could push them way beyond their ratings for the 30L-1, that was a long time ago. Despite their fragile nature, I had four of them in a Gonset GSB-201 that could literally have all four tubes glowing red and producing 800W output power, and the darned things didn't fail -- they lasted several years.

    I don't think you can do that with 'today's' tubes. And maybe can't ever do that again.

    The Chinese 3-500Zs such as the RFP branded ones seem quite good. My AL-80B came from the factory with a European made Philips tube that lasted five years of very heavy use; but I switched to an RFP brand Chinese tube almost nine years ago, and again through heavy use it still works fine with no signs of degradation. They seemed to have found the formula, and RFP does test them and offer a good warranty, which they do honor.

    The Chinese 8877's are evidently okay also, and Alpha is using them. I understand they got the formula from Eimac, including some tooling and assembly/test procedures. Magnificent tube if you get a good one.:eek:

    I'd leave 811As to audio amp service where they're usually run at 1200V.
     
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