[Elecraft] ALC control of W6PQL amp from my K3

[John Simmons]

Jim and all:

I have been a ham and avid CW op since 1970. I remember the Drake twins 
having a wonderful sound on CW, an almost bell-like sound. Has anyone 
looked at the CW waveform of those old rigs compared to the new generation?

-John NI0K

> Jim Brown <mailto:jim at audiosystemsgroup.com>
> Saturday, March 09, 2019 3:34 PM
>
>
> I wouldn't call that affection, but rather disgust. And I wouldn't 
> blame it entirely on how they control power.
>
> Several years ago, I produced a study of ARRL Lab reviews of the CW 
> bandwidth of about 20 transceivers, including some of the most 
> expensive. The best (the cleanest) was the K3, followed by the Kenwood 
> TS590. The worst were Yaesu rigs, with Icom about half as bad.
>
> The study is here. http://k9yc.com/TXNoise.pdf
>
> Not included in the analysis are the current generation of Flex rigs, 
> which, when tested by ARRL Labs were pretty dirty, but made pretty 
> clean by new firmware released not much later. Also not included was 
> the improvement to the Yaesu rigs by new firmware released after I 
> leaked a preliminary version of my study to someone who I strongly 
> suspected would pass it along to the factory. :) The improvement is 
> documented here.
>
> http://k9yc.com/FTDX5000_Report.pdf
>
> A primary contributor to excessive bandwidth is excessively fast 
> rise/fall time of keying, and the best rigs (the K3 and the Flex 6000 
> series) carefully shape keying to minimize CW bandwidth while 
> maintaining clearly defined keying. The worst rigs do none of that, 
> include controls that allow the user to change the rise/fall time, and 
> set a fast (worst) time as the default.
>
> 73, Jim K9YC
>
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> Jim Brown <mailto:jim at audiosystemsgroup.com>
> Saturday, March 09, 2019 2:38 PM
>
>
> No, it does not. It is science. ALC should NEVER be used to set the 
> output power of a power amplifier, because doing so produces lots of 
> distortion (splatter, clicks). ALC should be used ONLY to protect the 
> power amp from damage in the event of problems in the antenna system 
> or operator error.
>
> 73, Jim K9YC
>
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> KENT TRIMBLE <mailto:k9ztv at socket.net>
> Saturday, March 09, 2019 11:59 AM
> Along with this, it should be noted (especially for new Amateurs) that 
> . . .
>
> Don is correct (always is) concerning the non-employment of ALC with 
> respect to Elecraft transceivers which produce power differently from 
> other brands.  On this reflector, the recommendation not to use ALC 
> pertains solely to Elecraft products.
>
> However, many Elecraft owners own and operate other brands of 
> transceivers and amplifiers.  When using those other brands, the 
> instructions provided in the transceiver manual AND the instructions 
> provided in the amplifier manual about using ALC should be followed, 
> especially with solid state amplifiers. Those instructions often 
> differ from those recommended by Elecraft.  Some brands require a 
> one-time ALC calibration procedure prior to use.  Once properly 
> configured, they are usually free of the distortion Don rightfully 
> talks about.
>
> As a friend of mine puts it, the ALC controversy borders on being a 
> religious issue.
>
> 73,
>
> Kent  K9ZTV
>
>
>
>
>
>
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> Don Wilhelm <mailto:donwilh at embarqmail.com>
> Saturday, March 09, 2019 11:01 AM
> Bob,
>
> It is important to understand that ALC does not control the amplifier, 
> it is an attempt by the amplifier to control the transceiver.
>
> ALC is sent FROM the amplifier in an attempt to control the power of 
> the transceiver.
>
> Used indiscriminately, that will cause distortion in the driving 
> transciver.
>
> Elecraft does not recommend the use of ALC for power control because 
> of that.  Set the power output of the transceiver to drive the 
> amplifier properly and adjust the amplifier ALC to produce no ALC at 
> that point. If the amplifier has fault detection, then ALC can be used 
> to drop input power if a fault occurs - that is the only legitimate 
> use of ALC.
>
> So in many cases, an ALC connection is not needed.
>
> 73,
> Don W3FPR
>
>
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