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Re: Kx3 power output

Posted by W7GJ, Lance on Mar 03, 2012; 12:27am
URL: http://elecraft.85.s1.nabble.com/Kx3-power-output-tp7338175p7338521.html

Think it would work at 10 in JT65A mode?  48 seconds on and 72 seconds off, hour
after hour?  VY 73, Lance



On 3/3/2012 12:17 AM, wayne burdick [via Elecraft] wrote:

> 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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