[AMPS] CW/SSB Tune Up
Mon, 8 Oct 2001 21:35:12 -0700
>Aloha Rich and others who have responded, hope
>I have the following correct:
>In response to my question,
>> >Question: leave things just as they are now, or increase
>> >the drive power to bring the SSB peak readings back up
>> >near 1500 watts?
>> tune for max out with max drive, provided that the anode
>> current rating is observed.
>Yes, in my Henry Amplifier manual, Henry publishes a full page
>of your instructions on the importance of correct amplifier
>tuning. They indicate that the info is reprinted from the March
>1989 QST, an article by you, AG6K. But no specific details!
>Now, Ok, here is the tricky part.
>1. My amp has an Eimac 3CX3000A7
>tube. The supply voltage, key up, is about 6200! Unit is
>a Henry 8K. So per your method, I would set this puppy up
>for the about 5+kW output on CW into the Bird Coax Resistor,
>8890-300 dummy load load, for starters.
For starters, you need at least 450w drive. PEP out should be around 9
assuming 60% efficiency.
>Presume I would use the 50 wpm dits for this tune up. Would
>keep tweaking until the maximum output cababilities
>of the amplifier seem to have been reached. Wow,
>have no idea how high that might be!
It's a bunch with 6kVDC.
>Next step written by others:
> 2. Then adjust the loading control such that the output
> decreases by about 50-75 watts. Said to lower IMD.
Not helpful with this bottle because the IMD c, 16db better than the
> 3. Reduce the drive to the amplifier to obtain maximum
>legal output as seen on your dummy load/peak reading digital
Doing such be reducing mic. gain is best.
>Depending upon the band, this would cut the input drive to the
>amp from about 200 to 275 watts down to about 60 or so,
>approximately to come down from the 5000+ output to the Bird.
>I have NEVER had the amp put out such power(5000+W) to the
>dummy load or anywhere else. I might be afraid to, hi.
5 out is no big deal, It's not even one S-unit more than the legal
> These 200+ watt drive powers are from Paul Johnson at Henry in
>the data sheets that came with my amplifier a few years ago.
>4. Assuming that your antenna system is 50R +j0, switch
> to the antenna system.
>With the tuner between the amp output and the antenna feed, this
>5. You should see very little change in power output as
> viewed on the peak reading watt meter whether you operate
> in cw or ssb mode.
True - with a resonant choke PS.
>6. You can adjust the power output control of the exciter
> slightly to achieve the maximum legal power output of the
> amplifier as seen on the in-line peak reading watt meter.
>Ok, have I got it correct? Bought the 8K a few years ago in
>order to have very clean, cool, lowest possible distortion and
>the legal output power.
Sure, but one should not run less power than is needed to communicate.
If it takes 9 to rise above jammers/sociopaths, that's just fine. "Speak
softly and carry a big stick."
- R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.
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