[Elecraft] KX1 low output on 7mHz

Ron Reis nthdegreeinc at gmail.com
Tue Jan 10 10:46:45 EST 2017


Recently finished the build of my KX1 and noticed that the power output on
7 mHz is lower than on 14 mHz.  The manual states that it is typically the
opposite, with 14 mHz 0.2 - 0.3W lower.
I checked the voltage across a dummy load with my scope, converting P-P to
RMS and the using the 50 ohm load to calculate the output in Watts.
Working into 50 ohms gives me 2.7W out on 7 and 3.6W on 14.  Seems like the
14 mHz output is about right, but something is wrong with 7 mHz.
The manual suggested squeezing the turns on L2 to occupy about 60% of the
circumference of the core.  Rather than improving things, the output on 7
mHz was reduced to about 2.3W, so I went back to the normal distribution of
the coils.
All of this is with a 14.0VDC well filtered and regulated power supply.  In
each case the VSWR was reported at 1.0 with the 50 ohm dummy load.

Any ideas anyone?

Thanks and 73,
Ron
KB6K


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