The band input line pins are set up as input on the Arduino. As
such, they are high impedance, so I don't think there is any way
to drive them from the Arduino (short of changing the
program/sketch). I normally leave my switch controller powered
on with the K3 powered off, and have not experienced any problems.
If there were other things in the shack driving the lines, there
might be a over voltage issue for the Arduino, but I think there
would also be issues with the K3 driver circuitry. (One drives
high, one drives low and lots of current flows.)
73 Bill AE6JV
On 2/7/16 at 10:52 AM, jackbrin...@me.com (Jack Brindle) wrote:
This can work. But it can cause problems as well. You should
add isolation in the form of either small diodes (cathode
towards K3) or small resistors (maybe 100 ohms).
The problem is that if the Arduino is left powered on when the
K3 is off, the Arduino can actually leak power into the K3
through these connections and can actually power parts of the
K3 (as in parts, but not all, of the cpu). This false power can
lead to other problems, which is why we suggest the isolation diodes.
The second thing is to remember that 60 meters is coded as all
zeros. The K3 has pullup resistors on the band lines, which
will pull the band lines to whatever Vcc happens to be at that
time. When the K3 is off, Vcc is zero, which will be the value
of the band lines (i.e. not high-impedance). Thus when the K3
is off, you will see a band selection of 60 meters. KPA500
users see this as the KPA500 switches to 60 meters if it is
left powered up after the K3 is switched off.
Good luck with the project!
- Jack, W6FB
On Feb 7, 2016, at 9:47 AM, Bill Frantz <fra...@pwpconsult.com> wrote:
I have built a similar switch controller. If anyone wants a copy of the
details, please ask.
Specifically:
- Just connect te band lines directly to the Arduino inputs. It works fine.
- Don't know about cross band split. However K 3 power off and 60M look the
same.
- I don't bother. I don't change bands while transmitting. I'm not sure if the
K3 even supports it.
73 Bill AE6JV
On 2/7/16 at 3:38 AM, p...@tippete.net (Pierfrancesco Caci) wrote:
Hello,
I'm trying to make my own interface between the band data lines on the
accessory connector of the K3 and the remote antenna
switch. I have a few questions that I hope you can help me with:
- is it safe to just poll the band lines with the arduino
digital input
pins? I understand that my K3 is new enough to have the internal pull
up resistor. Should I put an isolation device inbetween?
- does the band data as provided by the K3 always track the
TX VFO?
Should I expect some weird situation if I ever try to do cross-band
split? - should I bother with asserting TX Inhibit and
keep it set for a few
milliseconds when I detect a band switch?
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(408)356-8506 | internet. I have DSL. | 16345 Englewood Ave
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