Back a bit, I had the need to drive a remote switch and something else
with the BCD band data.
For me there was simple PIC based solution. BCD input to PIC. PIC
programmed to switch to appropriate antennas . Input BCD data echoed to
other PIC outputs. PIC outputs buffered by a ULN2003's or 2n2222's.
73 de Brian/K3KO
On 3/11/2017 1:47 AM, Jack Brindle wrote:
As I recall, it is a standard LS TTL style open-drain driver, which means it
has a fan out of about 10 LS loads. You should be able to connect several
devices. Be sure they do not have pull-ups that are connected to higher that 5
volts (some band decoders have pull-ups to 12V). The K3 has internal pull-ups
to 5V, so having 12V on these lines will subject the K3 to 12V. The internal
pull-ups will limit the current, but if the K3 is off when the decoder is on,
you could get damage or even false powering of some of the K3 internal
components.
False powering means that the component is actually powered through an IO port
instead of its main supply line. This is a very bad situation that can damage
the part since it is powered incorrectly. It is also maddening to debug since
the part (possibly a processor) seems to be working when it should not be and
can actually do some very strange things.
73!
Jack, W6FB
On Mar 10, 2017, at 2:38 PM, NOEL POULIN <[email protected]> wrote:
Hi to all,
I am on the way to connect a Bandpasser2 (band data mode) on a K3s.
Later I would like also to connect a band decoder on the same radio to switch
coaxial stubs.
I wonder if the K3s can handle more than one device connected to the Band Data
signals.
I suppose that Elecraft band output is probably designed to drive one decoder
and this decoder is designed with current maximums for each port.
I would appreciate comments and good tips about that fact...
Thanks
Noel
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