OPTION AD is designed to interface an 8558 AutoTune with a 8525B & 8528 Transceiver
Layout:
Fitting Instructions:
Photo of board inside radio:
A common fault with the board is the transistors V5,V7,V9,V11 which are
BD675,
fail. An easy test for this is to attempt to tune the antenna with the
lid off the radio.
Touch each of these transistors in turn. If they are HOT,
replace them. Not much
else goes wrong with this board.