G'day, For what it's worth. Just completed a 31 day run of beacon operation, 4.5 hours/day, 12W QRSS10. KPA100 heat sink sitting at a steady +46C, no ill effects noticed. KPA100 outboard with KAT150. Regards, Mike VP8NO (IOTA SA-002) GQRP 10148 QRP-Canada #57 K2/100 #1400