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Re: [Amps] Alpha 87 (not 87A)

To: amps@contesting.com
Subject: Re: [Amps] Alpha 87 (not 87A)
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Tue, 7 Nov 2017 10:00:12 -0800
List-post: <mailto:amps@contesting.com>
On 11/7/2017 9:44 AM, Steve Wright wrote:
People seem to visualise all this heinous crap coming out of their antenna and taking away everyones' rights, but I challenge any person to furnish any sort of valid complaint regarding any harmonic.  And I mean a COMPLAINT, not someone three doors down being able to detect your 3F.

It is a serious mistake to view harmonics as the only product of distortion. Any mechanism that produces harmonics will also produce intermodulation, which shows up as clicks on CW and splatter on SSB. They are two heads of the same snake. We can kill harmonics by filtering them, but we can't do that with IMD.

K6XX, an engineer who works for Elecraft, mostly on their power amps, gave an excellent talk on this topic to our contest club several years ago. In it, he noted that the distortion increases a LOT in a power amp that is not properly tuned. For solid state amps, this tuning is accomplished by giving it a matched load, either the antenna itself, or with an antenna tuner. Bob is my neighbor, and we're both serious contesters (and also good friends). When I moved in 11 years ago, one of the first things he did was make sure that I knew how to tune my amps, and the importance of doing so.

http://k9yc.com/K6XXAmpTalk.pdf

73,Jim K9YC

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