On Fri,12/16/2016 6:37 AM, Jim Thomson wrote:
## Excellent presentation.
Thanks, but although I used Power Point to show the data, it's really
just an engineering report on lab work that I have done. And the only
place it's been presented is as this file on the internet.
## The k3 is a superb radio for cw. But its -29 db pep IMD3 on tx, is
nothing to brag about. The dishtronix at
-30 db pep IMD3 is no better.
2-tone IMD measurements are NOT the be-all and end-all of describing a
radio's performance. In ARRL Lab tests, the K3 showed the same superior
CW keying bandwidth that I measured, and when it was introduced in 2008,
was by far the best in that regard that ARRL had ever tested. The
current version, the K3S, introduced in 2014, is roughly 8-10 dB better!
And all it takes to make that improvement to a 2008 K3 is to replace the
synthesizer board, at a cost of about $250, and it's an easy field
replacement.
But back to IMD -- it is well known, and Elecraft says so, that IMD
performance improves a lot when the output power is reduced to the 50W
range, which is what it takes to drive most commercial power amps. K6XX,
who works for Elecraft, showed that in a talk he gave to the Northern
California Contest Club in 2013. It's on my website. Note that he was
NOT praising the radio -- the talk was about how to transmit the
cleanest possible signal. I contributed to the talk with on-air
measurements of some local signals that were driving both of us nuts,
and with a disciplined series of a neighbor's IC7600 (with his
cooperation).
http://k9yc.com/K6XXAmpTalk.pdf
73, Jim K9YC
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|