These things sure don’t like high SWR, as smoke came out of mine once!
I finally realised I was transmitting on 28MHz into my 50MHz yagi… Ooops!!!
Anyway… R23 crapped itself… big time. Went open circuit.
Refer to PBA overlay below.
Tom, K4ICJ, from JPS provided me with the following information:
R23 should be a 51 ohm 1W resistor.
What probably happened is that your 6 Meter Yagi looks like a very low impedance for 10 Meters and this did not allow the RF detector in the ANC-4 to develop enough voltage to operate the relay. Hence, your full transmit power on 10 Meters was absorbed by the 51 ohm resistor – at least for a little while.
You might want to check R24, R25 and R26 to make sure that they still read 51 ohms each
And a tip… do not mount R23 hard on the PCB – space it off the PCB by a few mm.
You can use ceramic beads for this purpose. At least you won’t char the PCB next time.