K3s/10: Max FP temp?

[Bill Leonard N0CU]

I am starting to use some digital modes and couldn't find any specs/guidelines on max power, duty cycle or FP temp. Running only 5W on JT65 (ie, 50% duty cycle) I see the FP temp get up to 43C after just one or two QSO's. Is an external fan recommended when using high duty cycle modes?

Thanks,

Bill N0CU