Amateur Radio

Packet Interface for the Yaesu FT-817


You use the information on this page ENTIRELY AT YOUR OWN RISK. I (the author of this page) will NOT be held responsible for anything that happens as a result of using this information.


In order to transmit packet data from the FT-817, the radio's PTT (Push To Talk) must be activated. AGWPE uses the RTS (Request To Send) pin on the serial port to signal this. A simple circuit can be used to achieve this, and is described in the following text.

Note that although this interface is intended for the Yaesu FT-817, it should be fairly easy to adapt it for other rigs with separate Transmit, Receive, PTT (Push To Talk) and Ground connections. The connector between the interface and the rig is all that will need to be changed. See your rig's instruction manual for connector details.

Some smaller handheld rigs (for example) do not have PTT connections. This interface will NOT work for these.

Required Components:

2 x 3.5mm Mono Plug
1 x 9 Way D-Type Socket
1 x CT-39A Packet Interface Cable (see note 1)
1 x 10k Resistor
1 x 2N3904 Transistor (see note 2)

Cable to connect 2 pins of D-Type socket to main circuit

Note 1:
This cable is sold by companies such as Waters and Stanton specifically for this purpose. Alternatively, many computer mice connect to the PC using a connector that fits in to the FT-817 data connecter. If you have any old mice with such a connector then it's lead could be used. Pinouts for the FT-817 data connector are shown in the FT-817 operating manual (page 41 in mine).

If you do use the CT-39A cable, the wires are colored as follows:

Color Data Pin Function
Brown 1 Data Input (Tx Audio)
Red 2 Data Ground
Orange 3 PTT (Push To Talk)
Yellow 4 Rx Data (9600 Hz)
Green 5 Rx Data (1200 Hz)
Blue 6 Squelch Status

Not all of the connectors on this will always be required. For APRS work (using UI-View) for example, only the Data Input, Data Ground, PTT and 1200 Hz Rx Data connections are necessary.

Note 2:
Pinouts for the 2N3904 Transistor, are as follows:


Now What?

In order to use this interface, the AGW Packet Engine (AGWPE) needs to be installed and set up. I won't describe how to do this here, as there is an excellent guide already available here. There are also links to the software from that page.

Once AGWPE has been started, the appropriate packet software (e.g. UI-View or WinPack) can be executed.

I'll look forward to seeing you on UI-View (144.800 MHz)...