Interfacing Nokia BSR / Kyodo KG110 radios to PC

Audio connections

Pinout

Modulator input is in pin 5. Output from discriminator can be found on pin 6. Modulator requires approximately 5 Vpp signal for 3kHz deviation so output level from cheap audio devices needs further amplification.

Radio controls

Insert a 10k potentiometer between pin 12 and ground for squelch control. Some other interesting control pins are 10 and 11 (Volume control for monitor speaker, insert speaker between pin 16 and ground or to the speaker connector if the radio unit has it installed) and 26 (S-meter).

PTT is controlled by connecting pin 15 to ground. COS information is on pin 9 (0/8 V signal).

Level conversions for PTT/COS

Depending on the control port used on PC, PTT/COS signals need some level conversion. Attached is a simple schematic for level conversions to serial port. Transistor and diode types are not critical, almost any generic ones will be ok on this use. rs232-conv

Example of amplifying and adjusting the audio signals

Couple of pictures of simple LM386-based amplifier built into the radio unit. _MG_2236 _MG_2237 _MG_2238 _MG_2239

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