Moon Bounce
This page will document my attempts with my college radio club, K2GXT, to successfully complete a EME contact. I pitched the idea to the club my senior year, and the goal was to complete it before I graduated and using majority of parts we already had. We also wanted to present it at Imagine RIT, a festival showing off student organizations and other projects at RIT.
Antenna - 18 Element UHF Cross Polarized Yagi
The antenna was one of the first parts chosen. The club already had an 18 element cross polarized UHF yagi. This gives about 14.76dBd of gain. The antenna did not have any mounting hardware with it, but has mounting holes.
To mount and control the antenna, a Yeasu G-5500DC was purchased. This was expensive at $750, but will be much easier than trying to homebrew something. It also will allow easy adjustment from afar. A speaker stand was used to hold the rotator and antenna.
Radio - Kenwood TR-9500
For the radio, a UHF transceiver that can do SSB is needed. The club has two options, a Kenwood TS-2000 or a Kenwood TR-9500. The TS-2000 has many more features and is more modern, but also much larger and more complex. The TR-9500 is the radio we went with.
The TR-9500 has 10W of power. This is not enough for EME. Luckily the club also has a Mirage D 1010 UHF amp. It gives 100W of power with 10W input. To get a higher signal on receive a KP-1/144 Mirage Pre-amp is used.
The radio, amp, pre-amp, and antenna are all attached using LMR-400. Due to the huge gain of the antenna, the safe distance from the antenna is 28ft in a controlled environment, and 62ft in an uncontrolled. We went with a 40ft run of LMR-400 to be a safe distance away.
To connect the TR-9500 to a computer for digital modes, the club luckily has a SignaLink USB Interface. Unfortunately they do not sell a cable for the TR-9500 as it is rather old. The radio front panel mic connector is a GX16-6 aviation style connector. The SignaLink conveniently uses a RJ45 connector. Using the pinout from SignaLink's website, a cable was assembled using an old ethernet cable. To get audio from the radio into the SignaLink an audio cable from the speaker out port on the radio is connected to the SignaLink.
Power
For power we used a Harbor Freight "Tail Gator" generator we were able to borrow from another club at RIT. One extension cord ran to the antenna where an Astron RS-35M supplied 12V for the pre-amp and amplifier. Another extension cord ran to the radio setup where the laptop, antenna rotator, and Mean Well LRS-350-12 power supply for the radio.
Radio setup facing the antenna
Rotator, Antenna, Pre-amp, Amp, and Power Supply
Radio Setup
First Attempt 3/24/2021
Our first attempt went pretty well. We were not able to hear our own echo or make any contacts, but we learned a lot and figured out some problems we hadn't thought of. A Harbor Freight Folding Camping Table ($30) was used to hold the radio, laptop, and rotator and worked surprisingly well. It's much lighter and cheaper than a folding table, but worked just as well.
Our main issue, we think, is getting audio back into the computer from the radio. We do not believe it was working at all. One major issue we had was not knowing the software well enough. More testing and prep should have been done to make sure we knew how to use the software correctly, and the SignaLink worked correctly with the radio.
Second Attempt 4/22/2021
Unfortunately our second attempt was foiled by the weather! Rochester had an April snow storm forcing us to cancel. As we approached the end of the semester, everyone got busy with classes and projects, and we were not able to reschedule.
Third Attempt 4/2/2022
The following year the club decided to try again. I had graduated but kept up with their efforts and provided help when able. The club was able to borrow an Icom IC-705 radio from one of the advisors, as well as a nicer generator. The 705 was a huge upgrade. We were able to have full computer control and audio over a single USB cable. The club managed to get a beautiful day to try again. The club also setup the rotator to be computer controlled to allow for easier and more accurate alignment. Unfortunately even with these changes we were not able to hear our own echo off the moon. The best guess is our power and gain is too low. From looking at the calculations, we are very close to the lower limit of receivable signal, and the calculations are best chance scenario. A larger amp and an antenna array would probably make it much easier to successfully hear our own echo.
