Post by andy on Jun 30, 2022 3:42:13 GMT -5
Some 30+ years ago I got the SB2 PTT switch and headset for my FT290. Since then it has been adapted a number of times to fit other radios and I now use it on my FT8900 together with a standard computer-type headset/boom mike. Since I couldn't find any details of the wiring online I've had a look inside and come up with the attached diagram which might be of interest. I also have the SB1 which is almost identical but differs in some of the resistor values.
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SB2 Dia.pdf (35.17 KB)