 |
| It's alive! Test bench setup with the Sub-Lunar SL-1 unit tracking the rising sun using PSTrotator software. |
For the last few years and eight State 23cm EME activations I've been keeping the 2.4M dish on the moon manually. This works pretty well if I remember to run out every 10 minutes to re-aim, and I have a visual moon. It certainly is simple, but a 2.4M dish's beamwidth is pushing the limit of manual aiming on 23cm.
With the ARRL EME contest in a few weeks and a Montana winter coming on it is finally time to embrace auto-tracking. A slew drive system was a bit beyond my budget, but Paul, W2HRO has just developed a tracking unit that I could afford. The Sub-Lunar SL-1 looks to be just the ticket to cut my workload down and keep my toes toasty warm while operating from the barn this winter.
My solution was to start with PSTRotator software running on my laptop to calculate the moon or sun position, and then talk to the Green Heron RT-21azel controller through two USB ports, the Green Heron RT-21azel runs the motors on the SL-1 rotor system, counts the pulses from both the azimuth and elevation encoders to calculate the dish's position, and reports back to the program where the dish is pointing. As you can tell basically the challenge was to integrate and debug three separate systems.
The Blue Heron Engineering RT-21azel controller is adaptable to so many different types of rotors it took a while to figure out how to teach it the specifics of both axis of the SL-1 rotor unit. The biggest key to success was telling Green Heron Engineering to configure the unit as a SPID rotor before shipping, then I could make a few modifications to the settings from there using the RT-21 Utility software to properly fine tune the SL-1 rotor unit. This ensured the unit came with the jumpers properly placed inside the tightly packed chassis.
I really like that you can reduce the size of the PSTRotator's screen once you're comfortable that everything is working well. Nice to save some laptop screen space.
 |
| The all important "STOP" button is still there. |
Long story short - after about eight hours of set up, some step-by-step debugging, and then cable building all the units play together nicely. When the moon gets a bit more declination I'll move things out to the barn and try a few contacts.
Hands on test: I spend about 12 hours on the moon during the ARRL EME contest the weekend of October 15/16 and the automatic tracking allowed me to work 56 stations on 23cm. A very good result for a 2.4M dish, around 300 watts at the feed, and near apogee. What a pleasure to just be on the moon come clouds or open skies!
 |
| The SL-1 kept me on the moon the whole weekend. |