Although it’s been a bit cold working in the garage over the last few days with the temperature close to 0°C, I’ve now completed the metal work for mounting the slew drive on a short stub mast.
The mast to bracket base plates I used for the 10GHz setup last year have been adapted for the dual axis slew drive. By installing the slew drive using M10 10mm spacers I have sufficient clearance between the two base plates for a full 360 deg.
The slew drive for the 10GHz offset dish arrived at the start of December and over the last few days I’ve been testing it on the bench with the KN3G controller I started working on in October.
The slew drive has two-channel Hall effect encoders built into each motor housing, one for azimuth positioning and one for elevation. Each sensor generates 2 pulses per revolution (ppr) on 2 channels but the KN3G controller just needs to use one channel.
For my first experiments on 10GHz I used a homebrew W1GHZ 10GHz transverter with a 432MHz IF. I recently bought a MKU 10 G5 transverter from Kuhne electronic (now part of Alaris Holdings) and plan to install it at the dish along with the DU3T LNA and Kuhne SSPA.
The transverter is small, measuring only 100 x 80 x 14mm, and has two 2.54mm pin headers, a 2 row 4 pin header for power and a 2 row 13 pin header for PTT, monitoring and frequency selection.
I’ve taken part in various EME contests on 2m since 2015 and I’m very pleased to have secured 1st place in the 144MHz Category C Mixed Mode section of the 10th A.R.I. Italian EME Trophy 2024. A big thank you to the organisers and all the stations that took part, it’s always a very enjoyable contest.
ARI EME Rules and Results
During the ARRL EME Contest in August and September I was struggling to keep the dish pointed at the moon using manual methods, especially for azimith positioning. I did some research and came to the conclusion that a dual axis slew drive, normally used for solar tracking, was the way to go. These slew drives have been in use for a number of years by radio amateurs across the world to move dishes much larger than 1m offset dish, so a 3 inch model should fine.
Since conducting the receive tests on 10GHz during the ARRL EME Contest last month I’ve been busy finalising the sequencer and control circuits and started testing the amplifiers on the bench. I’m hoping to have transmit capability for the second leg of the contest in two weeks time.
Microwave amplifiers for amateur use, especially solid state ones, are a lot more expensive than HF and VHF amplifiers, a combination of lack of demand and high device prices.
The dish used for the 10GHz EME tests during the ARRL contest has been moved to the back garden where I have visibility of the moon from 80 deg. to 235 deg. azimuth when it’s at 25 - 30 deg. elevation or more. At the moment the centre of the dish is only 1.4m off the ground so I’ll gain a bit more moon visibility when I move it higher.
Using the same dish setup from the 10GHz sun noise tests two days ago I got up early on 25 August to re-assemble the feedtray and control box. I was ready to run receive tests by 04:30 UTC but the moon was too high for the linear actuator controlling the dish elevation. I started around 05:30 UTC by trying to copy the DL0SHF beacon and stations reporting on the HB9Q logger.
Over the last couple of months I’ve managed to make some more progress with the small 10GHz station. I now have a simple dish support with elevation control using a linear actuator but azimuth control is still manual. I have also added a WR75 waveguide switch, DU3T LNA from PA0PLY along with a new linear feedhorn.
After assembling the feedhorn, waveguide switch and LNA on the feed tray I remembered that 10GHz EME operators in Europe use vertical polarisation.
After several failed attempts I managed to copy GB3SEE on 10368.850 MHz earlier this week with the dish and 10 GHz modules set-up on the front patio. The beacon is only around 8km from my QTH and was a good signal when I used the dish with a Bullseye LNB and SDR back in February. I’ve since found out that the beacon had been turned off for a while which would explain why I couldn’t copy anything a couple of weeks ago!
