On Thu, 29 Jan 2004 10:41:30 -0400, zemacy wrote:
>I need a bit of advise, I am unable to do CW-keying via a serial port while
>using writelog, I see no outgoing keying, the system stayes keyed down.
Two possible problems I've encountered (and fixed).
1) You don't have the required polarity inverter between the serial
line and the radio. This can be done with an NPN transistor and a 1K
resistor. The resistor goes between the serial keying line and the
base of the transistor, the collector goes to the radio keying line
(high), and the emitter goes to return of the keying line (low).
2) You do have the inverter, and it works, but there is RF getting into
either the keying line or the computer. This happens to me when I have
to use an improvised antenna that puts a lot of RF in the shack.
To figure out if #2 is the problem, try keying the transmitter with the
power output reduced to a very low level (or in code practice mode, if
your radio has one). If that fixes it, RFI is the problem.
The solution for RFI can include: ferrites on the serial cable,
shielding of the serial cable, and using twisted pairs for the serial
cable.
Jim K9YC
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