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:[email protected]>
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:[email protected]>
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:[email protected]>
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:[email protected]>
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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