Hi Manuel (Manuel Castro Caamaqo), in <000001bdb0b9$02cd76e0$c0c37ac3@malone> on
 Jul 16 you wrote:

> (Sorry for my poor english)
> I am very interested in building a system of remote control for a similar
> RTX but old, it is the Kenwood TM-702, maybe can serve me as orientation the
> work made with TM-V7?, i'm sure some control IC exists with bus I2C in
> TM-702.

I'm not sure about it.  The TM-V7 does NOT use I2C itself for the display,
it has proprietary and undocumented a 3 wire pseudo asynchronous full
duplex serial protocol.  It's my chip that translates this protocol (which
I hacked with selfmade tools and a logic analyser) to I2C (could have been
any other protocol as well).  I think (haven't tried) the TM-707 uses the
same protocol low-level wise but may use other high level data structures.