Kenwood TM-231a/331a crossband repeater

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Joined: Wed Jul 28, 2021 4:02 pm

Kenwood TM-231a/331a crossband repeater

Post by w3tez » Wed Jul 28, 2021 4:20 pm

I have a dedicated rig for 220MHz but I also have a kenwood tm-231a 2 meter and a 331 220 as well. Im looking to make a low power crossband repeater out of the two so that I can take my 220 HT outside with me and still work the guys on 146 simplex or take the 2 meter ht outside and work the guys on 220 simplex. I know this can be done but I looked at the panel mount mic jack pin outs and it goes as follows for both radios.

pin 1- mic audio
pin 2- ptt
pin 3- down button
pin 4- up button
pin 5-+ 8 volts some models 10mA
pin 6- N/C some models
pin 7- Mic Ground(audio ground)
pin 8- Ground(standby)

Ive seen this done many of times but the configuration is always different depending on which brand and series radios you use. Ive seen this done with a pair of yaesu ft 2311rm radios for a 1.2GHz repeater. But the website would not give any details as to what pins were crossed in the 8 pin to 8 pin homebrew cable to link the two radios together. Can i link the two radios together just alone on the mic jacks, or do i have to use the mic jacks and tap into the configuration with outputs out of the external speaker jack as well. Once i know what pins i have to cross of each radio i can make the cable up to link them together i have tons of 8 pin mic plugs, speaker jacks, wire etc... thats no biggie.

Ive been frying my brain on this and cannot come to a conclusion that makes any sense. would i take the pin 8 of one radio and run it to pin 7 of the other and vice versa to make it cross band then just hook up pins 1 and 2 the same and negate pins 3 4 5 and 6. Or would i have to run jacks into the external speaker outputs on each radio and then wire the audio outputs to the mic audio pins and then the speaker jack grounds to the ptt but wouldnt that lock the radios up in transmit with no switching? I know this is simple common sense to some and Im probably over looking it. How do i key one radio up when the other receives?


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