Author Topic: TTL port for remoting TH-742 Display  (Read 1949 times)

kc6wrd

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TTL port for remoting TH-742 Display
« on: 2010-05-07, 04:14:24 »
I have set up my 1258 pair for remoting my Kenwood TH-742. I use 220 Mhz and The
TH-x42 & x41 radios are the only ones made that both do 220 Mhz and use a Detachable Displays.
The audio set up works well but, I cannot get the display to remote.

I used the 1258's TTL ports and when I press the display's power on button it lights up but the display is blank. I've tried every combination of settings I could find -- no joy. Looking at the schematics for the TH-x42 it appears that is uses no protocol at all. In other words the 1258s need to be transparent. So that when the Display (control head) CPU raises or lowers it's ouput line to the local 1258 control end of the link, the remote 1258 radio end 1258 needs to raise or lower its output line to the 742 radio. Data transfered the other direction, works the same way. The circuit description says the data rate is 31250 bps.

Will the 1258s operate as described above? If not how about adding that mode?