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
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