![]() ![]() The SWR instrument mis-reads due to RF interference.There are several possible reasons for this, e.g.: Timing diagrams of the EDX-2 control signals If the transmitter does not send (sufficient) RF, the RDX-2 relinquishes the KEY signal 330 msec after activating that signal.T 4 = T 4 + 8 msec: the transmitter relinquishes the START signal and stops transmitting the carrier.upon finishing the tuning process, the EDX-2 relinquishes the KEY signal to the transmitter. T 3 = T 2 + T tune: the EDX-2 tunes (typ.T 2 = T 1 + 2 msec: in response to the active KEY signal, the DX-70 sends a carrier (3-10 watt).Pull-down in the EDX-2 is open-collector. ![]() In the DX-70, the KEY input is pulled up to +5 VDC.T 1 = T 0 + 15 msec: the EDX-2 responds by asserting the active-low KEY signal to the EDX-2.Pull-down in the DX-70 is open-collector. In the EDX-2, the START input is pulled up to +5 VDC.The transceiver asserts the active-low ( = pull-down) START signal to the EDX-2. T 0: the operator activates the 'tune' function on the DX-70 transceiver.The tuning process is quite simple, see the timing diagrams below:
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