[TRLog] I need help interfacing IC706MKII

Larry Weaver n6tw@csi.com
Thu, 10 Jun 1999 10:17:59 -0700

>I want to use an IC706MKII as 2nd radio (using a TS940S as 1st radio). Do I
>really need that CT-17 interface? Is there a cheaper work around? Can I key
>the IC706 with the same keying transistor Isetup  use for the TS940S?
>help somebody. Thanks in advance.

First, I use the same keying circuit as used with my TS450, worked fine in
the recent CW WPX

You need the CT-17 (or one you can build for considerably less money) to
convert the RS-232 signal levels to the TTL levels used by ICOM CI-V
interfaces. A circuit for doing this is in a QST article, Feb. 1992. The
circuit diagram is available on the WWW at


A printed circuit board is available from Far Circuits at


for $3.50US.

There is also as circuit diagram which has been used with an IC706 at



Larry N6TW

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