> Does such a product exist? I've only seen units providing
say 4 relay
> closures, which are far too few. This application really
needs a minimum
> of 16 "virtual wires", with capability to add further
blocks.
Ian,
When I lived in Cleveland Ohio I had a single very long
coaxial cable to a field where I had receiving antennas. I
used tones that were part of a BCD encoding system to drive
relays. I used NE555's to generate the tones and those phase
lock loop decoders (567's or whatever number they were) to
decode them and TTL logic. I multiplexed the tones on the
cable with signals and a 48 volt AC power supply voltage to
run preamps, attenuators, and directional switching systems.
I think I could control about 64 different functions.
I'm sure it would be easier to do something these days.
At my present QTH I use BCD encoded control lines. Three
conductors select 8 antennas, a 6-pair underground telephone
cable handles all my receiving arrays. When or if I need
more wires (they are full now) I'll start to multiplex with
voltages by using -dc, +dc, and ac. I like my hardware to be
simple because of lightning.
DX Engineering sells a little box that provides the
multiplexed voltages.
73 Tom
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