Posted by
wayne burdick on
Mar 03, 2012; 12:17am
URL: http://elecraft.85.s1.nabble.com/Kx3-power-output-tp7338175p7338488.html
Jim Dunstan wrote:
> The KX3 specifications indicate a nominal 10 watts output. When
> operating a mode such as PSK, which presents a continuous output,
> what is the recommended power output?
We recommend using 5 W for data modes and keeping transmissions
reasonably short. However, you can definitely use full power (up to 12
W) if the duty cycle is low, such as during hunt-and-pounce in a
contest. Of course as the duty cycle goes up, so will the PA and case
temperature, and eventually the KX3 may automatically roll back your
power output.
I just did a test using the built-in PSK-D mode, alternately
transmitting and receiving for 20 seconds each (simulating short
contest contacts). At 12 watts (20 meters), the temperature never got
high enough to roll back power during ten minutes of this.
I then tested the KX3's high-efficiency TX mode, which reduces current
drain by roughly 50% for a given power level. This mode kicks in at at
5.0 W or less in CW/FSK-D modes, and at 3.0 W or less in all other
modes. So I set power to 3.0 W in PSK-D mode, which is amazingly
effective given the S/N ratio of PSK31, and transmitted continuously.
After 5 minutes the PA temperature was still increasing slowly, but
I'm guessing I could have gone on for another 5-10 minutes.
The lesson, here, is to let the other station transmit once in awhile :)
Wayne
N6KR
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