Re: [Elecraft] K3 band data lines

I've done an experiment. I got a 7805 and powered it from a separate power supply. The negative of the 7805 is connected to the GND of the arduino. If I connect the 5V from the 7805 to one of the digital inputs, the arduino powers up and executes my program, lighting up the leds as expected. If

Re: [Elecraft] K3 band data lines

The opto isn’t needed. Just a low-voltage-drop diode (1N5711 should work) with cathode towards the K3, pullup resistor (47K to 100K) to +5V (or whatever the Arduino runs on, might be 3.3V), then the Arduino input pin. This will protect the Arduino from being falsely powered from the K3. This

Re: [Elecraft] K3 band data lines

I'm not familiar with Arduino circuit details, however... logic inputs typically have a clamp diode to Vcc. So, if you are applying 5V to an input without powering the circuit, in other words, Vcc=0, then you are forward biasing the protection diode. This is very likely what is powering the

[Elecraft] K3 band data lines

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

Re: [Elecraft] K3 band data lines

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

Re: [Elecraft] K3 band data lines

Thanks Bill. My point about the tx inhibit was that I plan to have a "manual selection" button, and I was thinking that maybe it would be nice to have a "fool avoidance" built in. The fool being me, of course. Pf > "Bill" == Bill Frantz writes: Bill> I have

Re: [Elecraft] K3 band data lines

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

Re: [Elecraft] K3 band data lines

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