> Many 2-channel RC transmitters contain the Signetic chip (NE5040??) which
> >is actually a 7-channel encoder.  You just need to connect additional
> >pots to the unused pins.  Such a modified transmitter would still be
> >"dumb," so including a PIC for digital processing makes a lot of sense.
> >
> Mike,
>
>     Thank you for the ideas! I realyy have to rethink on all of them, and
> also have a look on the Signetics chip.
The Signetics chip set is the NE5044 and 5045 7 channel encoder and
decoder. They were
used in about 90% of r/c radios up to the eary '90s. Their NE544 was
very popular as the servo
control chip. ACE r/c used to sell rf boards for you own tx projects
plus you could buy any
of there radio components. Not sure if this is still true after their
takeover.