EQUIPMENT

The following are details of the portable 6m EME station  used since VK9CGJ and VK9XGJ in 2017. 

ANTENNA: I use an M2 6M8GJ  yagi mounted on an M2 24' Portable Mast . At the beginning of 2020, I built a new lighter weight manual elevation mount that allows me to elevation the antenna to aim it at the moon as it moves across the sky. There is a complete description of how I put together the antenna and mount, and how I raise it into position, along with photographs of the antenna in operation here. Here is a short video showing me raising the assembled antenna when I was operating from Palau in 2016. You can see from the video why it is important for me to try to find a place to set up where I have enough open space to raise the antenna easily. Here is a photo showing the antenna installation in Nauru in 2018, which was erected and operated in a much more challenging confined space than I usually try to find.

FEEDLINE: I use Times Microwave LMR-600 Coaxial Cable to connect the antenna to the station in order to keep the feedline loss well under 1 dB. This is essential because the signals coming back from the moon are very weak (and rarely audible to the human ear), it is essential to try to capture as much of the signal as possible before they reach the receiver preamplifier. I try to use as short a piece as possible, but much of that depends on the site where I am able to set up the station and antenna. In Nauru during 2018, and in Bolivia in 2019, the antenna was close enough to the station to allow me to use only 50' of LMR-600 Ultra Flex. In 2017 in Cocos/Keeling Islands and Christmas Island, I had to use closer to 120', to reach an open area large enough for the antenna. I always take 50' of LMR-600 Ultra Flex to connect to the antenna, since it accommodates the flexing around the elevation mount and guy lines.  When I am going to need extra feedline, I usually take a 25' piece of standard LMR-600, which is lighter weight than the Ultra Flex, to reach to the equipment.  I also take a pair of four foot long pieces of LMR-600 and a pair of four foot long pieces of LMR-400 to use as interconnecting cables for the equipment and/or to further extend the feedline if necessary.

TRANSCEIVER: To generate the RF signals on 50.190 MHz, I use Yaesu FT-857 amateur radio transceiver. I have modified it slightly as shown here, to provide an output to automatically turn on my 50 MHz amplifier.

AMPLIFIER: I use an M2 Inc. 6M1K2 amplifier to boost the maximum 50 MHz output from my station to 1000 watts output. Due to the low duty cycle of JT65A mode (transmitting only 46.8 seconds during each 2 minute period), and the additional attenuation due to coaxial cable feedline loss to the antenna, the average power output at the antenna typically is 340 watts when aimed up at the moon.

WATTMETER: The amplifier output power and antenna match are monitored with a Daiwa CN-101L wattmeter.

PREAMPLIFIER: To boost the received signal, I use an ARR MSP50VDG RF-switched preamplifier that I modified to provide output to a separate receiver.

COMPUTER INTERFACE:  A RIGblaster Plug & Play  interface is used to cleanly connect the JT65A mode audio tones generated by the WSJT10 program in my computer to modulate the USB signal of my FT-857 transceiver.

RECEIVER: The separate receiver I use is a USB RTL Dongle (NooElec NESDR SMArt - Premium RTL-SDR w/ Aluminum Enclosure 0.5PPM TCXO ). A small 50 MHz bandpass filter from Down East Microwave is used ahead of the RTL Dongle to prevent overload from out of band signals. The output of the RTL Dongle is processed by the computer program SDR-Console Version 3. The output from the SDR-Console program is sent via Virtual Audio Cable to the WSJT-X computer program to decode the JT65A modulated signals coming from the moon.
 
SOFTWARE: As explained above, I use JT65A mode from the WSJT-X software package, with the option selected to use the standard EME report of OOO and the "Shorthand" (Sh) reports of RO, RRR and 73. There are several reasons for using this version:

    1. JT65A in WSJT-X is slightly more sensitive on very weak signals than the JT65A in WSJT10.  And many of the signals I am trying to decode with my small 6m EME station are very weak!
    2. The "Wide Graph" in WSJT-X provides a much larger display of the bandpass than SpecJT in WSJT10.  This makes it easier for me to spot callers who are spread out more widely.
    3. Starting with WSJT-X version 2, there is a 64 bit version, which decodes much more quickly on my 64 bit Windows 10 laptop.

COMPUTER: My computer had been an MSI GP72 7RDX Leopard  17" laptop running a Windows 10 64 bit operating system. Starting with S79GJ in 2019, I was forced to go with something more compact, so I got a DELL XPS-13 9370. It has more than high enough resolution on the screen for the WSJT-X WIDE GRAPH and is fast, with an Intel 8th generation Core i7 processor. It also has two free USB-C ports while plugged in, so I can connect my RIGblaster Plug and Play as well as my RTL Dongle receiver.

POWER SUPPLIES: When I have access to 230 VAC, I use a Meanwell RSP-3000-48  switching power supply to provide the 50 VDC required by the amplifier, and the PowerWerx SS-30DV 110/220 VAC switching power supply to provide 12 VDC for the transceiver and preamplifier.
The 50 VDC from the power supplies is connected to the 6M1K2 amplifier via a twisted pair of #8 stranded copper wire cables, attached to the #10 pigtails coming out of the amp using a 50A battery cable connector (NAPA #740234, like a really big Anderson Power Pole connector).  After connection failures in VK9 with the standard Yaesu 12 VDC molex power connector plug, I am also now using a NAPA #740234 for my 12 VDC connection to the FT-857.  In locations where I have only access to 110 VAC, I use a pair of Meanwell RSP-2000-48 connected in parallel.  These Meanwell RSP-2000-48 power supplies provided by the DX Shop are specially prepared to be able to handle full power for the duration of the JT65 transmissions.

OVERALL STATION SETUP: I also use ferrite filters on all computer and power leads to prevent RF pickup/generation. Here is photo of my station as described above, completely set up when I operated moonbounce on 50.190 MHz from Nauru in 2018.

Revised 4 February, 2020