>
>I have a pair of 3-500z tubes in my final. For tune up, I set 200ma grid,
>600ma plate on cw mode. Then, I back off just a little, and switch to SSB
>mode. The question I have is whether there is any need to use ALC with my
>final. There are several reasons I ask this:
>
>1. I seem to do fine without ALC. I have a scope on my xctr and final
>output, and have one and two tone test capability for signal monitoring.
>
>2. In the past, when I did use the ALC, I got squirrelly results in
tuning,
>from time-to-time, and therefore lacked confidence in the results. When
>that happened, I would disconnect from ALC, and go back to tuneup without
>it. The squirrelly results had nothing to do with the ALC. It was just
>there trying to do its job. Other factors were at work in the squirrelly
>tuning result. But, the ALC, in trying to do its job, was
>complicating/masking other problems.
>
>3. I get excellent on-the-air reports without ALC.
>
>4. I have several tranceivers that I can use to drive the final. Of the
>three, only one was designed to be compatible with the ALC of this final.
>Of the three, they all work fine as exciters.
>
>So, is there a strong case for ALC, when the capability is there?
The trouble with ALC is onset overshoot due to un-avoidable built-in
delay. A better solution is to not use ALC and to make the amplifier
happy with the drive level by adding RF-NFB R at the input
cheers, Ron, K5BDJ
>
>
>--
>FAQ on WWW: http://www.contesting.com/ampsfaq.html
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>Search: http://www.contesting.com/km9p/search.htm
>
>
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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