In message , Gazz writes
I have taken the 40 way channel selector switch out of an old CB radio,
and want to see if i can figure out how it works, with a view of using
it on my computer (i need 10 switch detents over a 90 degree arc for a
control lever, hence the 40 switch detents over 360 degrees of the CB
switch gives me what i want when i use a quarter of a turn on it)

The switch is made by uniden, and has the following markings on it...
SR-334, P-79 2-5A, they are stamped in, the UNIDEN word is cast in the
back plate as well as 'PSS-23'

i apeers to be made up of 4 x wafers, each individual wafer has 5 pins,
and they are stacked front to back, i.e. there's room for 6 pins, but
one is missing giving 2 space 3 pins, then the next wafer is 3 space 2
pins and repeat.

that gives a total of 20 pins,

i'm going to play with the multimeter on it, but wondered if anyone
knew how they work internaly,

i need to make it work like a 2 bit gray scale rotary encoder, know how
to do that with a single pole rotary switch where there's an obvious 1
common pin and the switched pins (uses a few diodes to give the A, B,
AB, 0, A, B AB etc output) but can i do that with this switch?

In the 1980s, I modified a few UK CB sets for use at the top end of the
amateur 10m band. Most designs used a limited variety of dedicated
synthesiser ICs - the LC7317 being a typical example (the intention
being to make it difficult to move them off the original CB
frequencies), and the channel was selected by a binary coded decimal
address. The channel selection switch was designed to provide the
appropriate address directly. However, I don't really have any immediate
access to any further useful information.
--
Ian