On 3/9/2019 12:57 PM, Bob McGraw K4TAX wrote:
Yes and some brand(s) of radios are affectionately known as "click
generators" being the result of they way they control power.
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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