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Re: [CQ-Contest] Handicap For Dirty Rigs

To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] Handicap For Dirty Rigs
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: k9yc@arrl.net
Date: Mon, 20 Oct 2014 22:43:09 -0700
List-post: <cq-contest@contesting.com">mailto:cq-contest@contesting.com>
On 10/20/2014 2:05 PM, Stuart Phillips wrote:
The FCC publishes required levels of operation for several aspects of radio performance but 
is silent on matters like phase noise etc beyond using phrases like “commonly accepted 
engineering practice”.

Hi Stu,

As I wrote in TXNoise.pdf,

"FCC Rules 97.307 (a) No amateur station transmission shall occupy more bandwidth than necessary for the information rate and emission type being transmitted, in accordance with good amateur practice. Figure 12 clearly shows that Yaesu and Icom transceivers are using 3 times more bandwidth than Kenwood and 5 times more than Elecraft. As I read the Rules, this puts anyone using them in violation of 97.307 (a)."

Follow my logic. Elecraft, with their K3, have defined "good amateur practice" with respect to CW. Kenwood's TS590S, less than half the cost of a K3, is next best, and the modern ICOM and Yeasu rigs are much worse. I've seen data from Flex for their 6xxx-series rigs putting them in a class with the K3 for cleanliness, but these data have not been verified by ARRL. In simple terms, today's ICOM and Yeasu rigs are in violation because they use MUCH more than the minimum bandwidth needed for transmission. 97.307 (b) and 97.307 (c) expand upon that standard.

As I see it (and as principal author of all AES Standards on EMC, I have used similar wording), "good amateur practice" with respect to occupied bandwidth was specifically written into the Rules to not tie the hands of innovative designers and allow the State of the Art to advance. Wayne Burdick, Elecraft chief engineer, showed many (all?) of his cards in an Appendix to my report. There is no magic there, simply good, innovative engineering. The methods are available to all.

For years, we were taught that CW bandwidth was related to CW speed, which is a total falsehood -- CW bandwidth is solely a function of rise and fall waveforms, distortion in RF stages, including the output, and phase noise.

73, Jim K9YC


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