[WriteLog] Updated Port Setup

[Michael C. Joens]

A couple years ago I posted a setup for multiple serial ports. It is now 
part of the WriteLog web site, which I consider quite an honor. Well, for 
those interested, it's time to update my setup. Lightning destroyed my PC 
and radio three months ago, and the insurance bought me new equipment. So 
now I have an IC-756PRO (replaces the 756) and I built a new PC with a 
Pentium 4. The "problem" with the new computer is that it has no ISA slots. 
As a matter of fact, most new PC's have only PCI slots.

So here is my setup, using three COM ports. Actually, the PCI bus makes 
some things easier because ports can share interrupts.

Port   IRQ   Base    Purpose
           Address
COM1    4    03F8    PTT, CW, FSK
COM2    9    D400    Modem
COM5   10    DFA0    Rig control
COM6   10    DF68    Packet
LPT1    7    0378    Printer
LPT2   10    DC20    (not used)*
Sound  11    DF00    Soundblaster PCI128
Netw.  03    D800    Network card
Mouse  12   (none)   Mouse

* I had planned to use LPT2 for CW keying, but it turns out I didn't need 
it.

COM1 is on the motherboard. The Intel D850GB motherboard has only 1 COM 
port (but it has 4 USB ports). Other boards may have 2 COM ports.
COM2 is assigned to the modem. The Actiontec modem is controller-based 
(rare these days) and lets you choose the port.
COM5, COM6 and LPT2 are on a PCI add-on card. CompUSA sells two different 
types. The one I use has the two COM ports on the board and the LPT port 
uses a short cable.
The Soundblaster PCI card works like a charm. It installs with "legacy" 
drivers that emulate the ISA bus environment. There used to be problems 
with PCI-based sound cards, but this one is compatible with all the 
programs I have.

Additional hardware:

- Rig control interface (CT-17). Depends on your radio.
- Level shifters for FSK, CW and the PTT line. I use optocouplers now, but 
2N2222's work too.
- Isolation transformer from rig output to soundboard.
- For PSK/SSTV I use an isolation transformer between the soundboard and 
the computer. A small relay connects the sound to the radio's accessory 
input when the computer pulls the PTT (RTS on COM1) line. That way I don't 
get interference when I use the microphone. The IC-756PRO has a digital SSB 
mode, so it's easy to cut off the microphone in digital modes. This is much 
simpler than my previous arrangement.
- A Top Ten coax relay box for antenna switching. The Top Ten decoder reads 
the band voltage from the radio. Alternately, you can use the LPT2 port to 
drive any antenna switching arrangement you may have.

I hope this helps some folks set up the ports for WriteLog. If anyone is 
interested in the computer-to-rig interface I built, send me an email 
(direct) and I'll send you the schematic.

Have fun, see you in the pile-ups!

Michael Joens, K1JE