The image above shows our station’s equipment dedicated to EME and Satellite operations. We built some shelves to make room for all of the equipment and create space to move our Satellite Ground Station 4.0 to this same area. The components in our 2m EME station include (left to right):
- M2 Antennas S2 Sequencer
- Icom IC-9700 Transceiver with a Leo Bodnar GPDSO and Reference Injection Board
- M2 Antennas 2M-1K2 1200W 2m Amplifier
- Green Heron Engineering RT-21 Az/El Rotator Controller
- FUNCube Pro+ SDR Dongle (not visible above)
- Transmit/Receive Relay System to enable dual-receivers/decoders (not visible above)
We’ll explain each of these components and the supporting shack infrastructure we are using for EME below.
Phase 1 EME Station Architecture
Unfortunately, the LinkRF Receiver and Sound Card to enable a full MAP65 Adaptive Polarity installation are not currently available. As a result, we’ve created a Phase I Architecture that uses an SDR Dongle and manual selection of Receive Polarity via a switch. We also added a receive splitter and a Transmit/Receive relay in front of an Icom IC-9700 Transceiver, which is dedicated to our EME setup to enable both the MAP65 and one of either the WSJT10 or WSJT-X Software Decoders to operate simultaneously.
This approach has some significant advantages when conditions are poor, as one of either MAP65 or WSJT10/WSJT-X will often decode a marginal signal when the other will not. More on this in the next article in this series which will explain the software we are using more.
Transceiver, SDR Receiver, and Sequencing
A combination of an Icom IC-9700 Transceiver and M2 Antennas S2 Sequencer handle the Transmit side of our EME Station, including the associated sequencing of the preamplifiers and Transmit/Receive Switching, which is part of our Antenna System. The IC-9700’s receiver is also used with the WSJT10 Decoder in our setup.
IC-9700 Frequency Drift and Stability
To ensure good frequency stability and limit IC-9700 frequency drift in our setup, we installed a Reference Injection Board from Leo Bodnar in our IC-9700. The Reference Injection Board uses Leo Bodnar’s Mini Precision GPS Reference Clock (the small device on top of our IC-9700 in the photo above) to lock the IC-9700 to a highly accurate GPS-sourced clock. The installation and configuration of the Reference Injection Board in our IC-9700 were simple, and Leo Bodnar’s website covers the installation and setup procedure for these components.
FUNcube Dongle Pro+
In our setup, we used a FUNcube Dongle Pro+ as a second Software Defined Radio (SDR) Receiver and as an I/Q source to drive the MAP65 Software. Information on configuring the MAP65 software to work with this dongle can be found here.
The diagram above shows the RF Paths and associated sequencing in our Version 1 EME Station. A Manual Antenna Switch is used to select either Horizontal or Vertical polarity when in receive mode. The S2 Sequencer handles polarity selection during transmission. A splitter divides the Rx signal between the FUNcube Pro+ Dongle for MAP65 and a Transmit/Receive Switching Circuit in front of our IC-9700 Transceiver. The relay enables the IC-9700 to provide Transmit signals for the MAP65 and WSJT10/WSJT-X Software applications. The IC-9700 drives a 1.2 Kw Amplifier during Transmit, and the final Tx output is metered using a WaveNode WN-2 Wattmeter.
To enable both the receivers in our IC-9700 and the FUNcube Dongle to function simultaneously, we built a circuit using a CX800N DPDT RF Relay and a Mini-Circuits 2-Way RF Splitter. We also built a simple driver circuit for the relay using a Darlington Power Transistor and some protection diodes. The circuit enabled our S2 Sequencer to control the relay along with the rest of the sequencing required when changing our EME Station from Receive to Transmit and back.
Finally, we configured a 30mS transmit delay in our IC-9700 to ensure that the S2 Sequencer had some time to do its job as the station changed from Receive to Transmit. This delay and the Transmit delays built into the MAP65 and WSJT10 software ensure we will not hot-switch the MAP65 Preamp System on our tower. One must be very careful to ensure that RF power is not applied before the sequencer can transition to the Transmit state or damage to the Preamplifiers and/or relays at the tower will occur.
Amplifier and Rotator Controls
The Elevation Rotator from our Antenna System was added to the Green Heron RT-21 Az/El Rotator Controller previously installed in our shack, and both the Azimuth and Elevation Rotators were roughly calibrated. Our EME station requires quite a few USB connections to our Windows 10 Computer, so we added a powered USB hub to our setup. Chokes were added to the USB cables which run to our IC-9700 Transceiver and our FUNcube Dongle to minimize digital noise from getting into our receivers.
Our 2M-1K2 Amplifier can produce about 1KW of power on 2m when operating in JT65 mode, and this should be enough power for our planned EME wor. Our S2 Sequencer also controls the keying of our Amplifier as part of the T/R changeover sequence in our EME station.
We added a 2m high power sensor to the output of our Amplifier and connected it to a free port on one of the WaveNode WN-2 Wattmeters in our station to provide output and SWR monitoring of the Transmit output of our EME station.
Supporting EME Station Infrastructure
We had some work to do to configure our station’s antenna, grounding, and DC power infrastructure. We redid the manual switching in our VHF/UHF Antenna Switching consoles to accommodate our new EME Antenna System and prepare for our Satellite Station to be moved into our shack soon. The console on the right provides the Grounding of the Transmit and Receive sides of our EME Antenna System as well as the selection of the Antenna’s Horizontal or Vertical polarity for decoding.
We also expanded our station grounding system to provide a ground point directly behind our EME equipment. Our DC power system was also expanded to accommodate our EME equipment.
Our station already has a GPS Controlled NTP Time Server installed, and we’ll use it to ensure that the clock on the PC, which will run the MAP65 and WSJT10 software, will have very accurate clocks for JT65 decoding.
We already have cameras that cover our Main and Satellite Towers. We’ve added a third camera to allow us to view our EME Tower’s operation from our shack. This ensures that we can visually confirm the operation of our antennas and detect any problems should they occur.
All of the new EME equipment has to be integrated and tested with the software components which provide digital operation, tracking of the moon, logging, and other functions in our station. The software setup, as well as our initial experience with operating our new EME station, will be covered in the next article in this series.
You can read more about our EME station project via the links that follow:
- EME Station 2.0 Part 1 – Goals and Station Design
- EME Station 2.0 Part 2 – Excavation, Footings, and Conduits for New Tower
- EME Station 2.0 Part 3 – Phase Tuned Receive Coax Cables
- EME Station 2.0 Part 4 – New EME Tower Is Up!
- EME Station 2.0 Part 5 – Control Cables and Rotator Controller
- EME Station 2.0 Part 6 – Tower Grounding System
- EME Station 2.0 Part 7 – Building Antennas
- EME Station 2.0 Part 8 – Elevation Rotator Assembly and Sub-System Test
- EME Station 2.0 Part 9 – H-Frame Assembly
- EME Station 2.0 Part 10 – Antennas On The Tower
- EME Station 2.0 Part 12 – Station Software
- EME Station 2.0 Part 13 – H-Frame Enhancements
- EME Station 2.0 Part 14 – New 1.5 Kw Amplifier
If you’d like to learn more about How To Get Started in EME, check out the Nashua Area Radio Society Tech Night on this topic. You can find the EME Tech Night here.
A key part of optimizing our EME Station was to reduce RFI from the network in our home. You can read about the installation of Fiber Optic Networking to reduce RFI and improve our EME station’s performance here.