>
>One of the better articles on using/making a PA appeared in VHF
>Communications 4/1985 by DJ4GC "Two-metre Power Amplifier using Valve 4
>CX 1000 A" and "Power Amplifiers - How they are operated" with spectrum
>displays.
>
>The author discusses in detail the point that reducing mic. gain is no
>way to drive a PA, one needs to have an adjustable RF control. Reducing
>mic gain can have the effect of increasing intermods and splatter,
? I have not seen a case where advancing the mic. gain reduced the
observed level of on the air splatter.
>the object is to capture the exciter's ALC action in its linear range (at a
>medium to high mic gain setting), so that the ALC action is continually
>"on", not pulsing on and off only at voice peaks
? Presumably, eliminating commas and periods plus shortening the pause
between words would help greatly -- provided that one used near-max. mic.
gain. .
> achieve(the dreaded 1 ms pulse
>on various modern rigs). Also, too much RF level from the exciter
>increases the linear's IMD, and don't blame the poor LO or IMD of the
>exciter for this! Get a copy of the article, its well worth it.
>
>As they say, "if you are holding a hammer, everything looks like a nail"
>(hams read: "if you have a 2 kW linear, everything looks like an
>antenna, or smoke it").
>
>> Why pay good money for a tube and not utilize it's emissive capability?
>> However, one should not use more power than is necessary to
>> communicate. Power adjustment can be easily achieved by adjusting the
>> microphone gain control. My guess is that fewer than 0.001% of CBers and
>> fewer than 2% of hams would even consider deliberately turning down
>> microphone gain.
>
>For too optimistic, Rich....
>
- cheers, Ian.
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|