![]() ![]() It’s basically a very crude cable to repeat audio, and, key the transmitter. I brought a cheap cable on eBay, mainly for the connectors, but, I figured before I cut it about, I would make a schematic, in case I ever needed the cable. The signal diode prevents collisions and bus conflicts between TX and RX it is arranged so that the cathode is connected to the TX pin on the TTL adapter and the anode to the RX pin.Īn old faulty Ethernet cable was hacked about to make the connections. ![]() The signal pin used is pin 2, and typically orange. Using an Ethernet cable with standard wiring, the ground connection uses pin 5 of the Ethernet connector, which is usually blue-white. A standard silicon signal diode such as the 1N4148 (almost anything will do), and an RJ45 Ethernet connector to fit the microphone socket. It didn’t take long to reach success!Ī USB-TTL adapter such as those easily available on eBay was used, which cost around £1 (or a little more with genuine chip-sets on). Seeing they were available cheaply on eBay, and knowing the likely ‘guts’ of such a cable, I decided to experiment with some standard designs. While experimenting with radios for the MMDVM Project (and here), I needed a programming cable for some Motorola GM340 and GM380 radios.Ī friend of mine had access to the programming software through his job, but couldn’t locate his programming cable for these radios.
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