"Tuning Pulsers" - Ameritron ATP-102 and MFJ-216 -- Likes? Dislikes? Reduce abuse?

Discussion in 'Amateur Radio Amplifiers' started by WD5JOY, Jun 9, 2013.

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  1. WD5JOY

    WD5JOY Ham Member QRZ Page

    Is it really THIS simple? Setting controls at 10 o'clock and adjusting PLATE and LOAD as instructed appears to produce full power from the amp. Per the AL-811H "Supplemental Instructions" tuning WITH the PULSER is quick, accurate and less traumatic for not only the AMP, but old senile folks such as myself. I've never utilized a "pulser" - but Tom's suggestion that one be utilized is certainly not to be ignored. I AM a bit slower with the hands and eyes these days - and sticking to the "5 seconds ON - 15 seconds OFF" is sometimes tough (damn dead brain cells!).

    "Adjust the two front panel controls to a 10 o'clock position. With the amplifierin stand-by, push the Carrier Tune button and adjust the transceiver's power
    control to the rated drive power of the amplifier. Place the amplifier into
    operate mode and depress the pulse tune button on the MFJ-216 Deluxe
    Amplifier Saver. Tune the amplifier for peak output power."

    I am just a bit UNCLEAR as to how to be certain WHEN the proper "pulse rate and duty cycle" is set. I believe it should be visually obvious on the WATT METER, showing as a reduction in "peak power" or even "average power".

    I guess I am simply afraid I am missing the obvious while focusing on my own doubts as to MY properly operating the pulser. I know I ask for more hand-holding than the law allows, but am I over analyzing the 'pulser' and missing the simplicity of its operation??

    Thanks for holding Old Senile Don's hand once again! Sometimes the 'sinking in' process takes me longer than the law allows.:mad::mad::mad:

    73 and again - THANKS!

    Old Senile Don / WD5JOY
     
  2. WD5JOY

    WD5JOY Ham Member QRZ Page

    I did find and have 'read' this article by Tom - W8JI ....... "Loading and Tuning linear amplifier" @ http://www.w8ji.com/loading_amplifier.htm. Certainly an excellent article - however, Old Senile Don just can't seem to get what's left of his mind wrapped around the PROPER "Pulse Rate and DUty Cycle" aspect! Yes - it should be obvious, but I fear I'm missing the most important parameters (and probably most easily set) while focusing n the technical aspects of 'right and wrong' amplifier "tuning".

    Sorry to be focused on my self-doubt rather than focusing on that which I DO understand in spite of 'thinking myself stupid'.

    Old Senile Don - WD5JOY
    (As embarrassed at having to ASK as I am at my own self doubt. It hasn't always been this way.)
     
  3. KL7AJ

    KL7AJ Ham Member QRZ Page

    A tuning pulser allows you to tune for maximum PEP while keeping the dissipation to a low level. Anywhere around 10-20% duty cycle works fine.

    Eric
     
  4. KL7AJ

    KL7AJ Ham Member QRZ Page

    You can get similar results by sending a high speed string of Es with an electronic keyer. I did that for ages. :)
     
  5. K7ELP

    K7ELP Ham Member QRZ Page

    What need idea and technique. I remember well, the peaking the grid and dipping the plate.
    73
    Ned
     
  6. WD5JOY

    WD5JOY Ham Member QRZ Page

    I think this is what was / is confusing me Eric. When I set the "Pulse rate" at about 10 o'clock and advance the "Duty Cycle" to just beyond the same point it is THEN that I visually see the "Plate Current - Grid Current" 'NEEDLES' rapidly rise and fall just a SMALL amount. At this point I interpret this as "pulsing" and set the power to maximum RF OUT on the watt meter. Checking GRID CURRENT then shows it is indeed at "maximum" (peaked) while still less than the 2oo mA allowed. I typically run the INPUT POWER at 65 watts as suggested and this gives a cushion on GRID CURRENT - running right at 160 to 170 mA. I then reduce the EXCITER POWER just a tad until Grid Current falls to 150 mA and I see only a minimal drop in OUTPUT POWER. This seems to follow the suggested directions Tom discusses (??). As a final step - advance the LOAD (opening) just a bit and all seems well. In SSB - the PEAk POWER is between 650 - 700 watts.

    Slowly getting the drasp - I hope! In years past I never used a "pulser" - but sent a series of characters and peaked RF OUT then adjusted the LOAD a bit more. It's only now that I more a bit more slowly and the EYES adjust a bit slower that I figured the "pulser" would save damaging components - no matter how I tried to convince myself I can still do it the "old way". I know I'm slower and need all the 'protection' from remaining 'keyed' too long and causing damage that I did not it years gone by.:eek:

    IF I am grasping the "pulser" principal a bit more now - perhaps that damage will be minimized. This darned 'self-doubt' is such a PAIN! I still remember to drop my drawers to do my business - but have to triple check to be certain I used the Sears catalog to clean the remains!:mad::mad::eek::eek:

    Old Senile Don - WD5JOY
     
  7. WD5JOY

    WD5JOY Ham Member QRZ Page

    And THANKS for the comments and tips. I know I am a pain in the patootie - but some days are better than others. Sunday was a "confused day" made a bit cleared by kind folks.

    73
    Old Senile Don - WD5JOY
     
  8. KD3NE

    KD3NE Ham Member QRZ Page

    Thanks for the thread, I never knew about tuning pulsars. I guess I am just too old.

    I will say that with my new AL-82 Amp and reading Ameritron's tuning instructions things sounded different then they did 25 years ago. :)

    Now I am looking at a getting a tuning pulser.
     
  9. WD5JOY

    WD5JOY Ham Member QRZ Page

    Ha Ha (or is that Hi-Hi?) Gary! When I checked to get your name I saw your "line" ...... '[FONT=Lucida Grande, Lucida Sans, Arial, sans-serif]Old man with a new radio and a few accessories! LOL" ........... I know what you mean! Accessories abound and the "pulser" is the latest for old Don. It was a bit of a foreign concept at first and I wasn't certain I had it down in my mind - but, after re-reading and finally grasping the concept it became 50% clear! New 'stuff' ....... that has been around for awhile throws me quite easily nowadays.
    [/FONT]
    YES Ameritron's written 'tuning instructions' do seem different - while still being darn near the same - or so I am reminded by some old geezer friends. My 811H came with a 'supplemental' set of instructions which I believe were written by Tom W8JI who I believe is the man behind the design. They were better than the 'manual' BT FAR but still required slapping the amp with a steady RF punch and being ever so careful to limit the time to 5 seconds ON and 15 seconds OFF - which is where my trembling hands sometimes gave me issues. I was afraid I would cook the tubes in a short time or do even more damage to the other components. THUS - the "pulser" was suggested.

    Now ....... after finally grasping the proper setup of the "pulser" tuning is SO much easier and far better for the amp. Now it's a maximum of 15 seconds ON and 15 seconds OFF -- and I find that two cycles of tuning does the job. it is quite easy once understood. I do believe that this is a good little item and will prolong the amps life far beyond what I have left in my old bones! I hope NOT - but one never knows.

    Oh by the way .... I bought the Ameritron ATP-102 which I believe is the cloneof the MFJ-216.

    My ATP-102 came with a cable with an RCA plug on each end - which is fine if your rig has an RCA JACK for the 'CW KEY'. My Kenwoods do not so it necessitated replacing one RCA plug with a 1/8" mono phone plug for my TS-590S and a 1/4" for my Kenwood TS-450S. An easy 'fix' even for me .... I just did it when all body parts were working in unison. I used a six foot audio cable - removed both RCS plugs and soldered on the 1/8" and 1/4" plugs and all was set to go; well, set to go AFTER re-checking the proper 'positive / negative' placement of wire to plug connections about 36 times to be sure I didn't swap their placement in another moment of stupidity.

    I suppose the proverbial bottom line is ............ I like it .... it works well AND now fairly easily and I think it will add a lot of life to my toys.

    73 OM .... 73!

    Old Senile Don -- WD5JOY




     
  10. WA7PRC

    WA7PRC Ham Member QRZ Page

    I've never used a pulser. I just use an inexpensive and easy to use lab oscilloscope to tune for best power and linearity (when using SSB). Tuneup takes about 5 seconds, total.

    A suitable 'scope will have a vertical amplifier response at least twice as high as the highest RF you intend to view. For 30 MHz, a 60 MHz 'scope is sufficient. Expect to pay as little as $1/MHz. I use my olde Tektronix 2236 (100 MHz). I prefer a lab 'scope to a dedicated ham scope because they tend to be less expensive and have larger CRTs and have triggered sweep.

    We know that tuning for maximum steady-state carrier power will result in severe underloading of an amplifier and on SSB, severe splatter. W8JI has it correct about insufficient loading being a major cause of splatter. However, without using a 'scope or spectrum analyzer, you're working blindfolded, relying on "rule of thumb" methods of adjustment. Even simple SAs tend to be pricey but, a 'scope won't break the bank and will let you know if you're flat-topping.

    You can also load and drive the amplifier very modestly (to be reasonably sure you're not flat-topping). But, that is contrary to the point of having an amplifier -- you want more output, not less.
     
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