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.

I use an Icom IC-705 and a homebrew Arduino-based sequencer for my 10 GHz EME station and have completed many QSOs over the past 18 months. I put the sequencer together a couple of years ago and it follows the same pattern as many other designs, protecting the waveguide antenna switch and LNA. Part of the control circuitry is a transmit inhibit stage which applies -4 V to the ALC/SEND connector on the IC-705. This prevents RF from being generated when the PTT is keyed until the ALC voltage drops to 0 V. I used the same technique many years ago with an Icom 251E on 144 MHz, and decided to implement it here after reviewing the sequencer designed by Bertrand, VE2ZAZ / VA2IW [1].

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.

I finished building and testing the 10 GHz 25 W GaN PA at the end of February and installed it at the dish on 2 March. My first QSO was with ON5TA -16/-17, followed by OZ1LPR -2/-16, GW3KTH -19/-22 and IW2FZR -16/-18.

Good results had previously been achieved on 10 GHz EME using 10–12 W into a 1.2 m dish. Over the winter period, the decision was made to increase transmit power to approximately 25 W by constructing a higher-power amplifier stage.

With no prior experience in building RF power amplifiers at microwave frequencies, a substantial amount of time was spent reviewing published designs, conference proceedings, application notes and device data sheets. Detailed notes and test results were maintained throughout, helping to identify problems and make appropriate modifications.

I haven’t been active on 10GHz since the end of August, when I moved the dish to the front garden where I have more moon visibility to the west.

During October and November I moved the transverter and SMPS for the PA from the feedtray into a separate unit which is located under the the feedarm, close to the dish. I also made up some new feedarm supports for the dish as the previous ones were a bit short.

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.

KN3G controller

The combination of the KN3G controller and slew drive have been working well but occasionally I need to peak the dish on sun or moon noise. When I built the controller I didn’t use any manual switches - all of the main functions I need are available through the Nextion touch display.

After a few failed attempts early last month, a combination of good moon conditions and fine, dry weather towards the end of May/early June helped to complete my first 10GHz EME QSOs.

On 22 May I completed my first ever 10GHz EME QSO with OZ1FF -13/-20, followed by ON5TA -12/-15, F6BKB -15/-18 on 23 May, and ON5TA -16/-19, G4YTL -16/-22 on 25 May.

Over the last couple of weeks, whilst waiting for moon conditions to improve, I took the opportunity to tackle a few issues.

Frequency accuracy

I use an Icom IC-705 at 432MHz as the IF radio. To measure frequency accuracy I used WSJT-X in freqCal mode and harmonics from a Leo Bodnar GPSDO running at 10MHz fed through a 120dB attenuator. I also used the GB3VHF and GB3UHF beacons which can be copied at my QTH on a rubber duck antenna indoors.