Fldigi Users Manual  4.1.17
CW Keyline Configuration

fldigi supports CW keying using a serial port DTR or RTS signal line. The serial port may be on unique for keyline use or be a port shared with a PTT signal line. Shared ports include

  • RigCat serial port
  • Separate PTT serial port


fldigi must be in the CW mode, and the transceiver set to CW mode for the keyline to be active.
Configure the DTR/RTS keying on the "Modem/CW/DTR-RTS keying" tab:

config-cw-dtr-keying.png
CW DTR/RTS keyline configuration


Select shared port use by enabling either the RIGCAT, or Separate PTT box.

Select a unique serial port by selecting the port and enabling the Connect button.

For all port selections you need to specifiy the signal line, DTR or RTS, which is used for the keyline. If shared, it must not conflict with the PTT line.

The CW keyline timing may require compensation. This is highly dependent on both serial port hardware, pc architecture, and operating system. The combined effect of the three will be to lengthen the key down/up intervals. The calibrate button is used to measure the timing inaccuracy. The measurement is made by sending a sequence of ten "PARIS " strings at the current CW WPM setting. The time to transmit is measured and compared to the ideal timing, 1200 msec / WPM. Be aware that this may transmit the characters. Use low power or a dummy load for the test. If needed, the computed compensation value will be entered in the Comp control. You may also manually enter or change this value.


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