[ct-user] Serial interface & keying

waldemar@zedat.fu-berlin.de waldemar@zedat.fu-berlin.de
Mon, 10 Jan 2000 22:17:17 +0100

> > Yes you can use a single serial port simultaneously for rig control and for
> > CW keying, I have done so.  I use an ICOM781 and its interface only uses 3
> > wires (RX, TX and Ground).  The DTR line is free and you can use it for CW
> > keying using the appropriate transistor circuit shown in the CT manual.  I
> > have done this only with CT using DOS, I have not tried this with WinCT.
> >
> > It works, but there is a serious drawback, which could easily be fixed by
> > Ken (if  could get his attention):
> >
> > I start CT using a batch file, which first loads and starts the COMTRS's,
> > COM1 for rig control & CW keying, COM2 for PacketCluster TNC.  Immediately
> > after COMTSR for COM1 starts the radio goes into key down mode.  And it
> > stays in key down mode until CT loads, starts, gets to the final
> > screen--then you must hit one of the CW function keys to send something.
> > Only then does the key down condition clear. COMTSR is asserting DTR true
> > when it could be easily changed to do just the opposite at initialization.
> >
> > Of course you can switch your rig to SSB temporarily to get through this
> > frustrating problem, or you can switch to LPT keying which completely avoids
> > this problem.  I switched to LPT keying, purchasing a separate LPT card.
> >
> > COMTSR needs to be modified to correct this problem.

Thanks to all that answered my query. It really works!! I gived up 
every time my rig went online after starting comtsr2, but going 
through the procedure described above it really works!!
I use home-made interface consisting of one 74HCT04, 2 NPNs, 3 
resistors, a diode, a zener diode and a electrolyt-capacitor, all in 
SMD fitting in a 9 pin housing. Not very RS232 conform, but it 
works fine, now including keying :-)))

Thanks a lot

Waldek, DL7ANQ & SO6ANQ

If someone needs, I can post cirquit diagram, but it is not painted 
yet ;-))

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