FDK Multi750 * Mic wiring, Servicing and alignment details*

The FDK Multi-750e was launched in the UK in 1981. A 2m ham radio multimode tranceiver, at a good price, and with a matching 70cm transvertor controlled from the front panel. There are still a good number around, but many have stopped working because of a very common fault - the potentiometers on the PCB were verry prone to intermittent working - especially on the final amplifier board.
If you have one with problems, it really is worth giving all the pots a good clean, and sweeping the boards for 'dry' solder joints. Meanwhile I have a copy of the service manual as a series of GIF images which you can view and print out here.


The FDK750 is fitted with a 6 pin microphone socket.





used on packet or APRS A 2.5mm loudspeaker jack at the back of the FDK carries received audio to the TNC. Both TX and RX lines into the TNC are through a 180 degree 5 PIN DIN socket. The cable into the TNC is screened.

Clockwise from the indentation in the socket, looking at the radio mic socket:-

1. Earth
2. +5V
3. Up
4. PTT
5. Mic
6. (centre pin) Down

Multi 750e Servicing and alignment: