George,
Actually 53 degC is not that hot. Look at the specs for semiconductors
and you will find that is only a medium temperature.
Actually at 500mW, it is unlikely that the KX3 will be damaged by even a
continuous key-down.
If you are operating it outdoors, you should keep it out of direct sun.
If it concerns you, I would suggest adding one of the aftermarket heatsinks.
73,
Don W3FPR
On 9/9/2018 12:11 PM, George Pasek wrote:
I am using my KX3 as a WSPR beacon at 500mw with a Arduino based controller
which provides GPS time sync, WSPR data, and audio. Currently I am running
mono band at 1 two minute transmit cycle per 10 minute time block. Now I want
to add KX3 band switching to my controller and increase my T/R duty cycle.
Watching the PA.I current I see that my current 2 minute ON 8 minute OFF cycle
shows a 30c ON – 46c OFF temp range. Running a 2 minute ON 2 minute OFF cycle
shows a stabilized 36c – 49c range after about 5 ON/OFF cycles, and running
continuous transmit cycles stabilizes at 48c – 53c after 6 cycles. So based on
these 3 duty cycles I see a 16c, 13c, and a 5c temperature rise. The 2 on/8
off has the lowest max temp but the widest temp range, the continuous transmit
has the highest max temp but the lowest range. My plan would be to have my
controller switch the KX3 through 5 bands transmitting the 1 minute 53 seconds
on a band and switching to the next band during the 7 second opening.
I have done extended temperature calibration with the XG50 so frequency
stability should not be a issue.
My question is, 53c (127f) is hot, are there any thermo stress issues to the PA
or the KX3 in general with running any of these three duty cycles? Obviously I
don’t want to damage my KX3.
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