Serial Port Test by Colin Chidgey G3YHV
The Serial port tester program is used to test PTT and CW KEYING When using the DRT and RTS lines of the computer serial port.
The program Takes these lines from the normally low to the high state for 10 seconds.
If you build a simple transistor interface for keying the transmitter be aware that the low state of the RS232 port is MINUS 12 volts, the High state is PLUS 12 volts. On a laptop it is sometimes only 8 volts.