Batboard

I am trying to interface a "telephone style handset" (p/n RLN4756A) to the accessory port of the CDM 1250. The accy port provides floating spkr+ and spkr- pins. As far as I know, the handset has a common ground, mic high, ptt, and handset audio. I have all working except the handset audio.

The reason for connecting it to the accy port is because they still want the conventional mic hooked to the mic jack.

Does anybody have any expierences hooking this up?

Thanks!
-Sonny

Sonny,

You may be able to interface the handset audio through an audio isolation transformer. However, the audio level at the 16 pin accessory jack will directly correspond to the volume control on the radio. If someone were to crank up the volume, the handset audio would become very LOUD, making the handset unusable. You might be better off running the handset from the microphone jack, & connecting the hand-mic through the 16 pin accessory connector. It’s just a thought.

trg

Check out the thread "Second mic for CDM1550" in this forum

The "receiver" in the handset is fed thru a 1uf cap and a 1K resistor from one side of the radio's speaker line, other side is ground.