This interface works with the following
Kenwood radios: TS-50, TS-60, TS-140, TS-440, TS-450, TS-680,
TS-690, TS-711, TS-721, TS-790, TS-811, TS-850, TS-940, TS-950 and the R-5000.
Note: In addition to the interface I describe here, the
TS-711 and TS-811 require the Kenwood IF-10A
TS-940 requires Kenwood IF-10B
; and the TS-140 and TS-680 require the Kenwood IF-10C. The IF-10 interfaces can be built as is described here.
This interface can be built for around $20 including shipping. Because
the Kenwood radios use 5 volt TTL levels we use an FTDI USB
. I found several companies that produce FT232RL breakout
boards for around $14. NKC
was the one I purchased from, and they had the
six pin DIN plug necessary to connect to my Kenwood TS-850SAT.
The USB serial port and the Kenwood both are both data terminal
equipment (DTE) and neither is data communications equipment
(DCE). This means that signal and control wires must be crossed
over so the RX from one goes to the TX of the other and the RTS of one
goes to the CTS of the other. The levels of the FT232RL need to
be 5 volts, not 3.3 volts. This is accomplished by removing a
"jumper" solder bridge on the breakout board at SJ1 and soldering a
jumper from JP1 pin 1 to JP1 pin 8 (blue trace on the schematic
below). See the schematic below. The signals to and
from the Kenwood need to be inverted as well. You do that by
downloading the MPROG program from the FTDI web site
Once you have installed MPROG and the D2XX drivers which it requires,
start MPROG with the FTDI board connected to your computer's USB
port. The GUI interface is pretty intuitive. Below is a screen-shot with
the proper settings.
to scan for the device, and then check the check boxes for
inverting TXD, RXD, RTS, CTS and to make the LEDs follow the data on TX and RX, you need to set C0 through C4 as shown on the screen shot. Then you click the program
button. Now your device inverts those signals as is needed for
the Kenwood TTL interface.
It might be a good idea to slip small ferrite beads over end of each
wire except ground. I didn't think of that until I had soldered
it all up, but I may go back and do that sometime soon. It keeps
the RFI down around the shack. The lump you see in the USB cable
is a big ferrite bead.
Thanks to Robin Midgett, K4IDC for the screen-shot of the interface with the proper selections.