EME

In mid-August, I added a MODBUS RTU relay module to the Kuhne MKU 10 G5 breakout board, allowing the receive frequency to be switched between 10368 MHz and 10450 MHz from the 10 GHz controller in the shack. I used the Kuhne Suite software and its plug-in for the transverter, together with a USB-to-TTL interface connected to the transverter’s serial port, to test and verify the configuration. I also carried out tests using a MAX2870 signal source to confirm that signals at both 10368 MHz and 10450 MHz were being correctly converted down to the 144 MHz IF.

A few weeks before the first weekend of the 2.3 GHz and Up ARRL EME Contest I moved the 1.2 m offset dish I use for 10 GHz EME back to the rear garden. I had spent some time evaluating both positions and came to the conclusion that having more moon time towards the east would be better.

During the ARRL EME contest I completed 15 QSO’s on 10GHz, including 6 initials. I was very pleased to work ON4CDU, my first 1.2m dish QSO. Being able to peak the dish on moon noise using the new nudge switches was extremely useful and I consistently saw 0.5 - 0.7dB of moon noise.

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.

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.

In October 2023 I gained DXCC award #227 for 2m - all QSO’s were via EME.

This EME station map is based on data from the call3.txt database file maintained on the MMMonVHF site. The red dot indicating the location of a station is shown at the centre of their grid.

I have only included stations that have a 6 character QRA locator and an "EME" label and ignored stations marked as "Expedition".

This call3.txt data is maintained by users and therefore only as good as the information they supply. There may be stations that are inactive on EME, QRT or SK. If you want to be included on the map, or if your information is out of date please visit MMMonVHF - My VHF-Database data and add/update your entry.

In May 2021 I changed the feed arrangement on my 144MHz XPOL EME array to transmit right hand circular polarisation (RHCP). Circular polarisation (CP) is frequently used for EME on 1296MHz and above, it’s not so common on 144MHz or 432MHz. The main advantage of CP compared with horizontal or vertical polarisation is that losses due to Faraday rotation are minimised but there is a -3dB penalty when one station is using CP and the other is using linear polarisation.

In January 2022 my SSPA shut down with a high VSWR warning when I was operating the 2m EME station. I tracked the problem down to the masthead control box that contains the antenna changeover relays and LNA’s. After testing on the work bench I found one antenna changeover relay sticking in the “on” (energised) position after control voltage was removed. The relays are setup to be energised during receive cycles so if it’s stuck “on” I would have been transmitting into an open circuit. See Station - RHCP arrangement.

Background

The existing switching unit for my EME station is built around a sequencer designed by DL4KH that I bought at Ham Radio, Friedrichshafen back in 2005. This unit provides sequential control logic for the transverter, power amplifier and LNA and antenna changeover relays mounted at the masthead to prevent hot switching. The sequencer has five relay driven outputs with a 40ms delay between each stage. The delay can be changed by swapping out a resistor and jumpers can be used to set relay outputs to either the switching voltage or ground.