Another AL-811 Tuning Question(s)

Discussion in 'Amateur Radio Amplifiers' started by W1DLA, Dec 17, 2010.

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  1. W1DLA

    W1DLA Ham Member QRZ Page

    I got essential help here. The first message from WB2WIK solved almost all of my problems. The MFJ instructions are not clear about the "quickly tune Load and Plate" to max power stage (nor are the videos below) and just knowing (1) not to use too low of a power out of caution, and (2) upping the load to lower the grid during this process rather than lowering it to raise power, filled in the missing pieces for me.

    The MFJ videos, for those who come across the thread...

    http://www.youtube.com/watch?v=OT1UaCrVvd4
    http://www.youtube.com/watch?v=zPcfRfn_No0&feature=related

    ...and the AL-811 manual, contradict much of what was said here and I'd refer you to them.

    Thanks for the help. But, why do some folks always presume stupidity on the other end rather than their own misunderstanding of what's being said. Anyway, I said I have two meters, the MFJ does read peak, forward and reflected. Almost every instance above of somebody thinking I was doing something screwy was either a typo or a communication problem with email type discussion.

    QRT
     
  2. WG7X

    WG7X Platinum Subscriber Platinum Subscriber QRZ Page

    What we have here.... Is a failure to communicate!

    Thwack!

    :p

    Sorry OM the devil made me do it!

    73 Gary
     
  3. W1DLA

    W1DLA Ham Member QRZ Page

    160 solved

    P.S.

    The problem on 160 was the MFJ-962D tuner limits on 160. Tuned up using the Bird (and plate dip) on FM, looks fine. If the MFJ is in there it kinda loads up and SWR climbs as the carrier is on (2 sec, not long)...the Bird doesn't budge and another SWR meter from a friend doesn't budge. Tuned, once you switch to SSB with lower PEP out the MFJ and other SWR meters coincide. I should've focused there given the cautions about 160 in the 962D manual...again, thanks all...I'm squared away.
     
  4. W8JI

    W8JI Ham Member QRZ Page

    This thread is a great example of how Internet group sessions spiral into noise.

    Let me run through this for those interested.

    The 811 amp is dissipation limited. It, like the Collins and heath Warrior and other 811 amps, hammers the tubes pretty hard. This is OK if we don't apply full drive with the plate out of resonance or a really messed up load, but if we ever do that even for a dozen seconds it is really rough on tubes.

    Because of that problem the manual gives a rough starting position, and warns to make a first tuning attempt at low drive. Here is what the manual actually says as the entire tuning steps:

    [​IMG]

    Note that nowhere in that does it say to adjust the LOAD control at low power. It simply says peak the PLATE and then look for proper meter ratios between plate and grid. It says advance the load if grid is too high, and decrease the load if grid is too low.

    I don't think there is any way to make the manual more clear. It specifically says the final adjustment is at full drive, not to exceed certain limits of exciter power (80 watts) and that is ALL. It says to reduce power, back drive off. It NEVER says or implies in any way to retune at lower power.

    The manual warns to NOT retune at reduced power.

    If people follow the exact letter of the 811 manuals, both of which are nearly identical, there will be no problem.

    It is really just a three step process:

    1.) Check everything out and preset the amplifier for the band
    2.) Apply a safe amount of drive and dip the plate or peak the output. This makes sure it is in resonance.
    3.) Apply full safe drive and peak load and plate controls.
    4.) Reduce drive if you want to reduce power.

    There are some exception in the RTTY and FM sections, but nothing really conflicting with the basic tuning. The tuning method above is safe for the amp, and pretty simple. Other than the check out it is only three steps, and avoids slamming the tubes with unsafe currents out-of-resonance.

    Sometimes the best advice is RTFM. If there was a way to make it better, it would be rewritten.

    73 Tom
     
  5. K8MCN

    K8MCN XML Subscriber QRZ Page

    Tnx Tom-I followed your instructions 3 years ago and have never had any trouble or complaints!!
     
  6. W8JI

    W8JI Ham Member QRZ Page

    If anyone can think of what is confusing in this, please let me know!!!

    [​IMG]


    I have been looking it back over and maybe the use of Ip instead of staying with plate current in step 8 might cause a problem???


    Thanks, Tom
     
  7. W1DLA

    W1DLA Ham Member QRZ Page

    Confusing

    "Quickly adjust the plate and load" real clear...especially if the power to get to the 150ma is so low that power goes up as load goes down...

    Look guys, get a life. If the best you can do is chastise somebody who you don't even know the extent of their background or education I pity you. Let the thread die...I got what I needed from it.

    I'm sad to say that I've discovered two types of hams...those that are kind, helpful and ready to help others into the hobby. Those that are arrogant, defensive, take the opportunity to slam others to try to bolster their pathetic self images, and tune up maliciously on top of other folks. QRZ has both...get a life.

    Obviously I wouldn't have asked if it wasn't confusing to me. I showed to to several others and they felt the same. I've published more instructional material than all of you combined. I know what is clear and what is not. And, I was just looking for a little civil help. God this ranting is truly pathetic.

    P.S. MFJ manuals are as well know for their clarity as their products are for quality control.
     
    Last edited: Dec 19, 2010
  8. W8JI

    W8JI Ham Member QRZ Page

    I'm trying to improve the manual or learn what is wrong. Why not help instead of being nasty?
     
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I don't think the Ameritron manuals are great, either, although I haven't spent time reading all of them.

    Then again, I think the Yaesu manuals are mostly horrible, and Icom and Kenwood typically aren't too much better.

    Ten Tec manuals have been pretty good, I think. Haven't spent a lot of time with Elecraft or Flex.

    When writing a manual (which I did for a profession, back about 35 years ago:p) it's important to write it completely from the user's viewpoint, and not one's own. And then index it, for God's sake. With modern computer resources, this takes absolutely no time at all. I cannot imagine writing a manual without a 3-4 page index of every single thing anyone would want to look up: It's just too damned easy, but many do a very poor job of it, or don't do it at all.

    I wrote a book about 3 years ago about PCI Express stuff, for the computer industry. We sold several hundred thousand copies. Almost every response I received was, "Thanks for the amazing index...it saved me so much time."

    And a good index is the easiest part. All I do is go through the book (or manual, or article) from the first word to the last word, making each new "key word" an index topic. I put them all in Excel, and then when I'm finished I click on "sort alphabetically," and have an automatic index, sorted alphabetically. I could index the King James Bible in less than one day doing this.
     
  10. W8JI

    W8JI Ham Member QRZ Page

    Any constructive comments about what might make those instructions clearer would be great!!
     
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