UPDATE UPDATE UPDATE 1.13.17

UZ7HO version 0.96b and above has changed the Settings/Modem Mode from “VHF AX.25 1200bd” to “AFSK AX.25 1200bd”.


AGW Express by W2YG is no longer supported due to changes in Winlink Express (formerly RMS Express) that now allows the use of the UZ7HO Sound Modem.


The AGW Express / AGW PE setup had other uses such as running UISS by ON6MU to monitor the packet frequencies or to run TNCs  not supported by WL Express such as the KPC-2. AGW Express is still available on this site in the original Soundcard WinLink post ( Link ) but is in no way supported by SERC, or anyone else. Unless you are an AGW PE die hard or have a real good reason to stick with AGW Express, it is recommended you migrate to the UZ7HO solution.


You can monitor all packets on frequency using the UZ7HO Soundmodem just as you did with AGW PE / UISS.

W6CCD’s instructions have been modified slightly to account for homebrew soundcard interfaces.


UZ7HO SoundModem Installation

This procedure applies to use of the SignaLink USB for VHF Packet. It assumes that the SignaLink USB has been set up correctly as shown in the SignaLink operation and instruction manual. Particularly with respect to the Windows system sound settings.

  • Go to http://uz7.ho.ua/packetradio.htm and download the file soundmodemXX.zip.
  • The XX refers to the version number.
  • There are some other files you can download, but that one is the only one you need to run the program.
  • Unzip the file and copy the soundmodem.exe to a convenient folder. There is no installation required.
  • Run the .exe file. You may get a message from your Anti-Virus program. Ignore it.
  • On the SoundModem screen, click Settings/Devices.
  • Output and Input devices:
    • SignaLink USB: Select USB Audio CODEC for both Output and Input devices.
    • Homebrew interface: select your soundcard input and output connected to your interface.
  • Check – TX rotation
  • Check – Single channel output
  • Check – Color waterfall. This can use a lot of computer resources, so you may not want to check this. It will depend upon your computer’s CPU.
  • Check – Stop waterfall on minimize.
  • Check – Enabled for KISS Server Port. Do not check AGWPE Server Port.
  • PTT Port:
    • For the SignaLink USB this should be NONE
      • Make sure neither box is checked.
    • For a homebrew soundcard interface, using a com port for PTT then select the port you are using to key your rig.
      • You may need to experiment with the ‘Dual PTT’ and ‘Swap’ check boxes to get your PTT to function.
  • Click OK
  • Click – Settings/Modems
  • Check – Default settings
  • Check – KISS Optimization
  • Check – non-AX25 filter
  • Under Modem type ch: A
  • Set Mode to AFSK AX.25 1200bd. Note this was “VHF AX25 1200 bd” prior to v0.96b.
  • Click OK
  • Leave the SoundModem running, and start RMS Express. SoundModem can be minimized if you don’t care about the waterfall.
  • Set to Packet WL2K
  • Click – Open Session:
  • Click – Setup
  • Set Packet TNC Type: to KISS
  • Set Packet TNC Model: to ACKMODE
  • Set Serial Port: to TCP
  • TCP Host / Port will be set to 127.0.0.1 / 8100
  • Under TNC Parameters, select 1200 Baud.
  • Check – Enable IPoll (Bottom of screen)

At this point you should be able to click Start and connect with a gateway.
The normal sequence will be to plug in the SignaLink USB and turn it on. Then start the SoundModem and leave it running. Start RMS Express last and use it like you normally would.
With RMS Express set up like this, you can switch back and forth between VHF Packet and
Winmor without any changes, and not need a TNC for either one.

Original by Dick – W6CCD 9/03/2015 (Rev. 3)