After reading the Elecraft Technical Notes on their wonderful KPOD product, I’m so confident that it would be an absolutely awesome controller for my Arduino and Raspberry Pi projects that I just ordered a second one. The first one controls my K3, the second one will be used to develop software that sends input command packets to the Arduino or Raspberry Pi and then, code will send the appropriate control commands to the output.
My first project will be to control this antenna tuner – the Palstar BT1500A. Two stepper motors will turn the L and the C controls. Here’s the script for how it will work:
This is the exact same way that I would tune an antenna tuner in the shack. But my “Modified Bobtail” with its open feed works very well with this tuner remotely and at the base of the antenna. Because I am transmitting with 1500 watts I am not at all comfortable with trying to use a fully automatic remote tuner – as I have heard too many stories of people blowing up MFJ remote tuners at the base of their verticals. I am sure they were trying to use a shortened vertical on bands that caused excessive voltage at the base of their antenna, and that they never looked into N6BV’s TLW program that comes with the ARRL Antenna Book.
When I was using the Elecraft KPA-500 and KAT-500 in the shack I was basically “lazy” and just let it do its thing. It wasn’t very efficient, but I could be lazy. At 500 watts, you don’t see nearly the issues you do at 1500 watts. This is where QRO teaches lessons that QRP can’t.
I find because of the high voltages that can happen with 1500 watts at the base of a vertical – or vertical array – that I would rather take a few minutes to manually tune and then know there will be no arcing or sparking, and most importantly a nasty amplifier fault.
I have support from Elecraft, and will seek support from Adafruit – run by “Lady Ada” Limor Fried, AC2SN, and will get a proof of concept working and publish this in QST. Then I will open the project as an Open Source project.
If you are interested sooner than when the POC proves success – please let me know – I’d love to have contributors and collaborators!