Take 1, IC800D. Replace the loudspeaker with an 8 to 10 ohm resistor. Connect a small transformer across the loudspeaker (terminating resistor) to isolate the dstar receive audio from the FM radio. There is a +5 VDC signal from the micro in the ID800 used to mute the loudspeaker. This signal goes to nearly 0 VDC during receive. (The squelch signal on the ID800 does not work on DSTAR - only FM and maybe AM for packet connections). I used the 5V going to 0 V during receive to turn on a small PNP transistor used to turn on the transmitter on a MA/COM M3 repeater. I set the M3 up for duplex 4 wire audio. The 600 Ohm secondary from the ID800 goes to the line in on the M3.
The DSTAR to FM audio is 'reasonable' but I prefer the crisp audio from the ID800 to the more bass sounding audio from the M3. Next I used an 8 pin data connector in the mic jack of the ID800. Took RUS (receiver unsquelched) from the M3 to an NPN keying transistor, to the PTT lead on the ID800 (be careful - there is +DC in the mic connector and you could really do some damage connecting to the wrong pin. Finally I took line out from the M3 through a second 1:1 600 Ohm transformer with a pad to drop the level into the mic jack of the ID800. FM to DSTAR is marginal to acceptable as far as audio quality goes. Also the volume control on the ID800 needs to be set and taped in place for reasonable TX audio into the M3. The M3 is set up for 3 khz @ 1000hz = -=10 dbm 600 and vice versa. Channel guard adds 0.75 khz - to the TX setting. I did not leave the FM to DSTAR mic / ptt connection hooked up. I do leave DSTAR to FM connected and have the gateway connected to 5A in the morning and 1C afternoon - just to give the FM folks a taste of what DSTAR is like. Plan is to leave it a month or so, the then unhook it so I can have my ID800 back for fixed station operation. Your mileage may vary. I sure DON'T want to pollute a nice DSTAR network with not so good sounding FM, but I wouldn't criticize anyone for making such a connection (with prior consent of the reflector owner / operator and gateway operator and others who swim in the same stream) on a limited basis for demonstration purposes. (maybe 1 hour a week for a net for a month or so, but certainly not full time). Please don't start a war over this - my opinion only - 73 steve nu5d. PS - I am disappointed to say the least about the audio quality reports from unbiased listeners - also 30+ years in LMR and familiar with empahsis / de-emphasis, roll off, etc. sb Bob Witte K0NR wrote: > We've got a local D-STAR 70 cm repeater on the air and I am looking > at approaches to allow access via analog FM users. > (This is probably a religious issue, so please chill :-) -- There is more to ham radio.....
