Ian White G/GM3SEK wrote:
> I'm starting to lay out a new HF/VHF home station on a 1-acre site...
> and can already see the numbers of 200-500ft control cables expanding
> out-of-sight.
>
Hi Ian,
About 20 years or so ago I built a remote HF station that ran on a radio
link. For the controls I used a UART chip at each end. This gave
parallel to serial and serial back to parallel at the other end. It
provided 8 lines out. 4 of the lines were used as data lines which went
to a 4 bcd in to 10 line out chip.
The other 4 lines from the UART were used as address lines which fed bcd
decoders that could be latched or momentary as needed. The combination
provides 128 control lines each of which can be momentary or latched
functions by whatever logic you attach.
The serial data was put on the carrier of the control transmitter by an
fsk modulated tone that was above the audio so both control and audio
could be used at the same time. I used some Xr (sp?) chips for those
functions. If you run a single wire line no tones would be needed. Just
run the serial data from the UART's on the wire.
All this was done with no microprocessors.
Don't know if UART's are still available or not.
Another control device that would probably be simpler is garage door
opener chips. They have some that have 4 bcd (maybe more) lines in and
serial data out for the transmit end and a similar receiver chip with
serial in and bcd out. If you close one line on the transmit end it
gives a closed line out at the receive end.
Feed those into bcd to decimal chips and you are good to go.
They require quite wide band width as they use some rather narrow pulses
but should work fine on a single pair of wires or some of the remote
control frequencies such as the garage doors operate on. No good for the
ham bands.
73
Gary
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