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The drawing that you're using looks correct. You *should* have 8-9.6 VDC on the ext mic input because that's the bias voltage for the amplifier and electret element in whatever mic is used with the unit. Rx audio is low level audio at 4-600 mv, unbalanced to ground, so you can't simply connect a speaker to that pin, you need a power anplifier if you're going to drive a speaker.
Here is what I was aiming for http://www.storm.ca/~nand/990/RICK/rptr.pdf Using the M1225 and a maxtrac for a bidirectional setup. I was able to key the radios but thats about all. i was testing the setup one way with the maxtrac being the RX radio and was not geting any audio out of the m1225 on TX. Maybe the maxtracs pinout is the one in question? I was able to get the RX audio out of pin 11 though with a very small speaker.
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Both pinouts are correct, as far as the numbers go. The Maxtrac picture is shown as though one were looking at the connector on the back of the radio. The M1225 does not appear to be shown that way...it's been a while since I looked at which way the accessory plug goes into the M1225, but I believe it goes in "tab down", just like the Maxtrac. So, is it possible you're not looking at the correct pins on the M1225? If it plugs in 'tab down', use the Maxtrac pinout for both.
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