[Elecraft] KPA-1500 on digital modes

[Andy Durbin]

"Elecraft's published specs rate the KPA-1500 for 1500 watts output on all modes.  In prepping for this weekend's contest, I've been running it at closer to 700 watts, because I've found that even just running on CW, with its much lower duty cycle, my amp reaches 70C quickly. "

You seem to be assuming that the KPA1500 will run hotter at 1,500 W output than it does at 700 W output.   I have no data for the KPA1500 but my data for the KPA500 show peak heating is at about 250 W RF output.   If the KPA1500 is similar then 700 W RF output will be close to worst case heating.

If you want to reduce heating then ensuring the load is as well matched as possible may be more productive than running at reduced power output.

73,
Andy, k3wyc