[Elecraft] SWR - does it matter?

[Ken Roberson]

If you want your antenna match to be correct use aScopeMatch as I describe on my 630M web-site.

Thanks 73 Ken K5DNL

www.k5dnl.com

    On Wednesday, April 10, 2019, 9:03:48 AM CDT, Andy Durbin <a.durbin at msn.com> wrote:  
 
 As a counter to those who are asserting that SWR 1.5:1 is a good enough match for an antenna system I offer measured data for the KPA500.

At 14.005 MHz my KPA500, when connected to a 1.44:1 SWR load (R37, X9), had a PA dissipation of over 500 watts when producing 400 watts RF output.  When the load was changed to 1.30:1 (R39, X3) the PA dissipation was about 410 watts.  When the load was changed to SWR 1.07:1 (R49, X3) the PA dissipation was reduced to under 400 watts.  (The plots are far more informative than a text description but I can't post them here).

If you don't mind your KPA500 running hot, and are prepared to accept it shutting down with PA DISS fault, then 1.5:1 SWR may be good enough for you.  I'd rather know the complex impedance of the antenna system load and avoid loads that result in high PA dissipation.

73,
Andy, k3wyc






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