The u.rat world tour: First stop – EBARC

On Friday, August 11, I will kick off the first stop on the 2017 u.RAT World Tour at the East Bay Amateur Radio Club (EBARC): http://www.ebarc.org/events.htm The second stop on this World Tour will be Pacificon – Saturday morning (I’m waiting on the time slot at this point): http://pacificon.org/ You will notice that the Pacificon web site still points to last years event, so…

A Funny Thing Happened on the Way to the U.RAT . . .

OK, so that’s a bit dramatic – but I’ll be busy first wrapping up the final “packaging” of the u.RAT Demonstration Board, and then writing articles and presentations. I will submit the article to QST with the main theme one that I will repeat at EBARC and Pacificon – which is that the “Maker – Ham” connection is a real force to be reckoned…

Presenting at Pacificon 2017

I’ll be presenting at the Pacificon 2017 Antenna Forum on Friday and then again on Saturday. Friday’s presentation will be “Low Band DX Antennas” and will feature the Mod Bob and touch on the BT1500A with uRAT, and then on Saturday it will be all about the U.RAT from more of a ham – maker perspective. I’m quite excited about Pacificon this year, especially…

U.RAT Demo Board

The u.RAT with stepper motors bolted in and coupled to the variable capacitor and roller inductor The two drivers and Raspberry Pi Zero W will be placed in between the capacitor and inductor. I have an Astron switching supply and a 12v to 5 volt step down component to supply the stepper motors and the Raspberry Pi Zero W. The NEMA-23 steppers only draw…

Let’s Spin a Roller Inductor

As expected, even though the variable capacitor was a massive Palstar model, a roller inductor has more friction, hence requires more torque. When I spun it as fast as I could it drew just under 1 amp. That’s very reasonable. One BIG issue is that with “direct drive”, the set screws would unloosen – this is because the shafts of the stepper are stainless…

Let’s Spin a Variable Capacitor

There is more than enough torque for the large Palstar variable capacitor. There was little extra power drawn, but not much. I’ll try the roller inductor later today.

U.RAT Key Learnings

Here are some key design notes and learnings: I had to use a Raspberry Pi due to the fact that the KPOD driver software is written in C and compiled on Linux. The KPOD is a proprietary device using the HIDRAW protocol, so its not exactly the same as a keyboard or mouse The WiringPi library turns the interfacing part between software and pin…

The U.RAT Kill Switch and LCD Display

Spinning a capacitor is no problem – you can spin it as much as you’d like in either direction. But the roller inductor would not last if a high torque stepper motor keeps banging on its stops. My first idea (following the KISS rule) would be to just add some leds – green for L – and turn it on when the rocker switch…

U.RAT – Next Steps

I’ve cleaned up the uRAT code and removed probably 2/3rds of what was in the Utility KUSB that Paul, N6HZ wrote, and so now its close to as lean and mean as possible. I am sure if I download a code editor that has C dependency checking I can get rid of more lines – but for now its clean enough – all unused…

The uRAT Has Landed!

YEAH BABY, YEAH! The uRAT now works very nicely – exactly as I had envisioned it working: The “secret sauce” included: Elecraft sharing a KPOD utility that is part of their development and QA suite (thanks Paul, N6HZ and Eric, WA6HHQ!) WiringPi – Gordon Henderson of Devon, UK, who created a C library that makes it as easy to work with RaspberryPi GPIO as…