Technical Corner

In this section, you'll find schematics for interfacing your radio to the sound card, and other technical information. If there's something you'd like to see here, please let us know, and we'll see what we can do.

The schematics and information presented here apply to both ChromaPIX and W95SSTV, except where otherwise noted.

Windows ME and RS232 push-to-talk issues

Interface schematics and information

Sound card and other Application Notes

Windows ME and RS232 push-to-talk issues

The new "Millenium" or "ME" version of Windows may cause the RS232 DTR and RTS lines to go "high" when it loads, keying  your transmitter, and leaving it keyed.  In order to address that, we've written a small program, FIXCOM.EXE  .  Here's how it works:

In your AUTOEXEC.BAT or Startup group, put a reference to FIXCOM, and specify the COM port number you want to "fix".  For example,


will "fix" COM2 .  FIXCOM supports COM ports 1 - 8.  If you use more than one port, simply use two references, each for the desired port.  Again for example, we'll use COM1 and COM2:


You can download FIXCOM.EXE here.  (~32kb)

Also, Del Schier, K1UHF at West Mountain Radio has written a batch file to make it easy to use FIXCOM.  You can visit the RigBlaster support page for details.

Interface Schematics and Information

Click on the images below to display the schematics full-screen. Once the schematic is displayed, you can right-click on the full-size image to save it to your hard drive.

Interface schematic

Isolated interface, with level control and MIC/SSTV switching
(can be used with the optional RS232 PTT interface below)

RS-232 Push-to-talk interface
(can be used stand-alone, or with the interface above)

Yaesu FT-847 interface schematic
(Courtesy of Dan Huton, VA3JDH)

ICOM interface schematic (includes IC-706)
(Courtesy of Dan Huton, VA3JDH)

Application Notes

AN100 - Setting up the sound card

AN100 - Configurando la tarjeta de sonido (courtesy of PaulÝ N˙˝ez, EA3BLQ)

(2000) Silicon Pixels