GP68/AP73 mic/spk pinouts for APRS?

[Bob KB1MNE]

The more I look around the more I keep coming back to the GP68/AP73 series (warts an all) for cheap parts/project HTs...

Without rehashing the whole FCC type accepted or not debate...

Does anyone have pinout / PTT information on this radio series? For the prices that they're available at they seem like good candidates for portable packet in general and APRS in particular. Has anyone tried a GP68/AP73 series radio with a TNC or simple data injector like a TinyTrak/WxTrak?

[Tom in D.C.]

Bob,

The speaker/mic is the same as all the other dual-plug
Motorolas. The large jack is the audio out and the small
jack is the audio in. I believe that ordinary 1/8 and 3/32
plugs will fit. I'm using the same setup on my GTXs on
900 mHz. Cheap, dirty, and usually reliable.

Looking at a 9725D spkr/mic right now shows me two,
two-circuit plugs, so the PTT switch is probably in series with the
mic audio circuit if you're outboarding a control circuit.

BTW, the plug spacing is NOT the same as is found on
Icom/Kenwood/Vertex radios. Good old Motorola!

Regards,

[Will]

Reminder...the audio output/speaker leads must not be grounded.
The audio amplifier is a bridged circuit.

The sleve of the small plug, 2.5mm is ground, and ptt is any thing in series with the center pin, MIC Hi, on the 2.5mm plug.

Audio output is the center pin of the 3.5mm plug. A series capacitor is needed, 10 uf works ok.

Here is the S/M diagram: http://batlabs.enterzone.net/images/gpspkmk.gif

[Bob KB1MNE]

Here is the S/M diagram: http://batlabs.enterzone.net/images/gpspkmk.gif

Thanks! That's exactly what I needed! Now I at least have a chance to get it to make sense. (My last electronics class was 20 years ago... I know it's in there somewhere... )