Big Day on the 2-M EME Project

Wheeeeee!  Big-Time progress was made today.  I did some minor work on the antennas by covering the driven element screws with Coax-Seal, putting some Silica Gel packets in the T/R Relay - LNA box to keep down the condensation, taping some of the control lines together, and making a small re-alignment of the rearward boom.  

The next step was to see how far off my rotor indicators were from where they should be.  I had a good visual on the moon so I had Evelyn use the Rain Proof Hoist Crane Pendant to move the antennas as I stood out in the yard to visually align them with the moon.  Once we had the moon square in the sights of the antennas, I went inside and looked at where the MoonSked program said the moon really was in Azimuth and Elevation from my QTH, and compared that to what the rotors indicated on the EA4TX ARS-USB rotor controller.  I then repeated that same operation four more times over the next hour or two.  As it turned out, my Azimuth reading was consistently 7° greater than what it should be and my Elevation reading was 5° less than what it should be.  Here is what the antennas looked like when we had the pointing "nailed."  Note that in the photo below you can see the moon lined up with the left-hand antenna. (Click on any photo to see a larger image.)

Now here is where things got GOOD!  I have a "driver" program that interfaces between MoonSked and the EA4TX ARS-USB unit and in looking at it, there is a "Setup" button.  When I opened the setup screen, there were two adjustments to "compensate" the readings between the two.  I inserted a +7° in the Azimuth box and -5° in Elevation box and told the driver program to "AutoTrack" the moon.  It adjusted the rotors to exactly where they "should" be pointing and I ran out in the yard to see that BINGO! - the antennas were indeed pointed right at the Lunar Orb!  WHEEEEE!  This is HUGE for my project to have the antennas actually pointing at the moon consistently and the AutoTrack feature working to keep them pointed there regardless of whether or not I can see the moon!

After that, I began running WSJT 10.0 as well as the MAP65 program while the AutoTrack kept my antennas pointed at the moon.  After about an hour, I saw on the WSJT EME - 1 chat page that K9MRI was calling CQ on 144.149 MHz.  I put my K3S on that frequency and WHAM! - the WSJT 10.0 program copied his CQ!  At 2309 GMT I copied his first CQ and then at 2313 I copied him with the best signal strength of -18 dB:

231300  6  -18  2.9 -283  3 *      CQ K9MRI EN70             1  10

K9MRI is running 8-M2 XP28 Yagi's and 1 kW.  So, he has a pretty big signal.  However, it is interesting to note that at 2300 GMT, the Degradation is 5.8 dB so not the best of conditions.  That probably explains why I was not able to copy the two or three 2-yagi stations that K9MRI worked over the next hour or so.  Still, I'm totally PUMPED that my receive is doing as well as it is.

But, I noticed that while I could copy K9MRI just fine on WSJT 10.0, I had zero copy on MAP65.  I began looking to see what could be causing that program to not receive and realized that when I had selected the Audio Source (which was for the FUNcub Dongle Pro+ SDR Thumb Drive) I had chosen the DirectX audio stream.  There was also an MME audio stream so I selected that instead and a few minutes later, MAP65 copied K9MRI - SUCCESS!

Now as I sat at the computer, I could see both WSJT 10.0 and MAP65 copying the signals off the moon.  This is AWESOME!!!  One reason I was trying to get the MAP65 program running is that it basically works like CW Skimmer in that it listens to 60 kHz of the 2-M band all at once and copies EVERY station it hears.  It prints out the messages that those stations are sending along with the frequency they are transmitting on, the audio frequency offset and the signal strength!  Since I was only able to copy one station tonight, here on the right is the "Messages" window of MAP65 showing the signals I actually copied!

The color code gives the most recent messages in Red, older ones in Yellow and the oldest in Gray.  All I need now is to have a little better conditions so I can hear more stations to see just how valuable this MAP65 program will be to me.

I can't wait for conditions to get better.  And, I am really, really close to being able to transmit.  I have the TX feedline connected, the wiring of the amplifier power supply is nearly complete, and there is not too much I still need to do to finish off this project.  If nothing gets in my way, it should just be a few days until I can echo test.

NEWS FLASH!!!  -  As I was typing this, the screen I was typing on was covering the MAP65 screen.  I just took a look and WOW, I had copied another station off the moon:

149 -151 0 0110 2.6 -26 # CQ K5LA DM61 0 23 0

I actually copied two CQ's from K5LA and this was the strongest one.  K5LA runs four 9-element yagis and is located in El Paso, TX.

Finally, on the left is a shot of the antenna array.  You can see the feedlines from the back of each antenna connecting to the power divider, which then connects to the T/R Relay - LNA box on the rearward boom, and inside that PVC box is the T/R Relay and the LNA (preamp.)

Lots of work has gone into this setup and it's about time for it to pay off!  Right now the moon is down to under 14° Elevation so it's time to shut things down and hit the sack.  I took a look out the front door and the moon is beautifully hanging over Hurricane.  Maybe I'll keep the station listening for a little longer just in case a VK, ZL or JA shows up [grin].

P.S.  A ZL did indeed show up on the Chat page but my noise had jumped up to S-9 so there was no chance for me to copy him.   Another time - I will!

W8TN's 2-M EME Project

My last post was about my grandsons digging the hole for my new tower.  Why do I need a new tower?  Well, I'm building a moonbounce (EME or Earth-Moon-Earth) station for 2-M and need a place to mount the antennas.  This project has been in the planning stages for over 3 years now.  About 14 months ago I started to get serious and placed the order for one antenna.  Delays in shipping that antenna led to me adding a second antenna to the order and the 2 antennas were received from England on July 5th last year.  I chose the InnovAntenna 13el 144MHz LFA yagis as about the longest I could reasonably put up at my QTH.  Each antenna has 16.12 dBi Gain at 144.100 MHz on an 8.003m (3.85 λ or 26.26 foot) boom.  Two of them spaced 4m apart horizontally should give 19.05 dBi (16.9 dBd) total gain. This amount of antenna gain coupled to a 1,000 watt amplifier should give me a modest moonbounce station using WSJT software.  I will, of course, be limited to a single polarity and thus subject to dealing with Faraday Rotation but I should be able to work dozens if not hundreds of stations off the moon.

Block Diagram of 2-M EME Station

One major reason for choosing the LFA (Loop Fed Array) antenna is that it has been specifically designed to reduce the amount of noise that is normally received off the back and sides of the antenna.  The tight, highly suppressed pattern and closed loop fed system ensure everything from rain static to man-made noise are heavily reduced.  This is pretty much an essential feature of an antenna that is trying to hear the super-weak signals being reflected back from the moon.  It has a really excellent G/T figure (-1.33dB @ 144.100MHz) showing it is hearing very little from the rear and sides of the antenna.

To the left you can see the current block diagram of my 2-M EME station.  It has evolved as this project has progressed.  The diagram on the left is current as of October 29, 2017.  Click on any photos to see a larger image.

I started out planning for an extremely simple configuration that would just allow me to make the occasional EME QSO.  But, as planning progressed, I kept adding features to make it the most efficient and productive station I could manage.  To that end, I added the EA4TX Antenna Controller that when connected to software on my computer will automatically keep the antennas always pointed at the moon without the need for me to manually adjust the rotors.  I then added the BG7TBL GPS Disciplined Oscillator that will take signals from the GPS satellites and produce a highly accurate 10 MHz reference signal for my Elecraft K3S to ensure it is precisely on frequency.  This is very important with WSJT signals so I felt this would be something that would remove the necessity of my needing to manually insure the frequency accuracy of the radio.

Everything else in the system was chosen to keep the signal losses as low as possible.  Toward that end the preamp will be located as near as possible to the antennas.  The preamp will be directly connected to the T/R relay with a right-angle, double-male N-connector.  All control lines will be shielded.  All computer lines will have ferrites installed on them.  Low loss cables will be used throughout the system including 7/8-inch Heliax for the TX feedline.  The antennas are mounted right outside the shack to keep feedline losses to a minimum.  Using just two antennas is not going to make me a Big Gun.  But, if I can make those two antennas and the rest of the station perform to their maximum ability, I will do well.

I then decided to add the FUNcube Dongle to the system to allow me to see all the stations which I am able to hear who are bouncing off the moon at any particular time without the need to tune around for them or set schedules to work them!  Unlike HF, you usually can not "hear" the signals from the moon but the computer can.  However, it needs for you to be pretty close to the frequency of the signal in order for the computer to decode it.  The FUNcube Dongle is a SDR (Software Defined Radio) just the size of a USB Thumb Drive.  It can listen to a range of frequencies and decode (using the MAP65 software) all the stations in that range of frequencies at once.  You can think of it as acting like the CW Skimmer of moonbounce.  On the right you can see an image of one of the output screens in MAP65 when I ran it and used a sample file for testing.  You can see that it shows the frequency of each station along with what they were transmitting.  I am so excited to give this a try on real live EME signals!

One other very important part of this 2-M EME station is a good low-noise preamp.  To take full advantage of that item it needs to be mounted as close to the antennas as possible.  I purchased a couple of these preamps from WA2ODO and on the left you can see the Noise Figure Meter printout from the best of these two preamps.  Putting such a low-noise preamp right at the antennas will help to keep the system noise figure as low as possible.

As I continue to progress with this project I will Post articles here on my Blog about various aspects of what I'm doing.  Hopefully, before long I will be able to post the images of my first EME QSO's in a LONG time.  I was on 2-M moonbounce back in the 1980's but only made about a half dozen QSO's with CW.  It was huge fun but I'm expecting this new incarnation to be an order of magnitude better!