Conditions have been poor and the weather has been terrible, but I reached a small milestone: I completed a moonbounce QSO with my 100th unique station (initial), and have since gone on to work a couple more. I’m happy with that, given my ridiculously small antenna and the fact that I’m limited to moon-rise only. The low height of the antenna above ground (approximately 6 or 7m) results in only two usable ground-gain peaks (around 2.5 and 12 degrees elevation), so my windows of opportunity for EME are indeed very limited!

I’m sure there are people with similar systems to mine that have never considered EME, perhaps thinking their antenna is too small. Please do give it a go! As an incentive, here’s a few statistics from my 102 unique EME stations:

• Number of EME DXCC: 34 (15 are unique to EME)
• Number of EME Squares: 88
• Number of EME Fields: 22
• EME best dx: ZL3TY, RE57OM, 18956km

I’ve also heard quite a lot more stations that I’ve not yet worked, including a better ODX, so there could be more to come…

I arbitrarily chose the 100th initial as a target to reach before making any changes to the system. Now that’s done I can think about what to do – current plans are to add 70cms, and perhaps add elevation and/or a second 2m antenna.

By now, most VHF-ers have heard of the Graves radar on 143.050MHz in JN27si, France. The radar transmits very high effective radiated power (ERP) CW towards the southern sky at various azimuths switched in sequence and, apart from its intended purpose of tracking satellites for the French Air Force, provides a very useful beacon for radio hams. More details can be found on PE1ITR’s excellent webpage, here.

The ERP from Graves is high enough that it’s easy to receive moonbounce signals from it. In the past I have had excellent results using just a small 2m antenna, with enough signal to noise margin to suggest even smaller is possible – shown below is a 25 minute waterfall of signals captured from IO91wv in 2008, using just a 4el yagi fixed at around 100 degrees azimuth:

Signals from Graves radar using 4el yagi, as received in IO91wv.

Graves’ moonbounce signal is reliable enough that, by tracking the Moon’s azimuth with an antenna fixed at, or near, zero elevation, it’s possible to get some idea of what that antenna’s pattern looks like at higher elevations. There are (at least) a few caveats: Firstly the earth-moon-earth path is not 100% reliable or stable, so there will be signal variations that are unrelated to antenna performance; Secondly, 143.050MHz is some way away from the design frequency of a 2m yagi, so the antenna pattern will probably be skewed slightly; and Thirdly, Graves’ antenna pattern appears to be focused between 15 and 40 degrees elevation, so measurements need to be made when it sees the Moon within that window, which might preclude being able to test one’s own antenna at all (especially low) elevations. I decided to have a go at measuring it anyway, and was quite pleased with the results…

A quick run down of how my system is configured:

• My 2m antenna is an 11el F9FT, rotatable but with a fixed elevation of about 10 degrees. The rotator is computer-controllable, with an Easy Rotator Controller fitted to its control box.
• The antenna can track the Moon’s azimuth, using F1EHN’s superb free EME System software.
• Audio from my FT857D is fed to a Windows XP PC, via an isolated interface (bought from ebay, cheaper than I could have built it for).
• The audio is analysed, in this case, using DL4YHF’s excellent free Spectrum Lab software.

Spectrum lab isn’t necessarily the easiest thing to set up but it does provide powerful audio analysis features, which, incidentally, were hardly touched during this test! For this measurement I used Spectrum Lab’s plotting feature (Main menu->View/Windows->Watch List & plot window), with “watches” set for finding the peak signal (amplitude and frequency) within a small range of audio frequencies, targeted at where the signal from Graves was expected to be. Watches were also set to measure the base audio noise amplitude, and the peak-minus-noise amplitude.

With Spectrum Lab running as described above, I set the antenna tracking the Moon and started logging results from 15:26z on 13th November 2013. At this time the Moon was at 14 degrees above the horizon at JN27si, i.e. almost within the antenna pattern at Graves. Having to wait for the Moon to enter Graves’ beam pattern meant that the Moon was already almost 5 degrees above my horizon, already above my first ground gain peak: I don’t see that as a problem because I already know that the antenna works fine at very low elevations, I’m more interested in what happens higher up!

Running the measurements through to a little beyond 18:30z, when the Moon’s elevation at Graves went above 40 degrees, gave the following result:

Graves radar moonbounce signal plotted against time

The top graph shows the peak amplitude of the Graves moonbounce signal (green) and the average base noise amplitude (red) against time. The bottom graph shows the audio frequency of the Graves moonbounce signal with dial set to 143.049MHz USB, within a few tens of Hz (blue) and the difference between the two signals from the top graph (mauve). The slowly changing doppler as the Moon rises can be clearly seen on the blue trace, with a few “spikes” where the signal is too weak to get a lock.

As previously mentioned, I already know that I get a good ground-gain peak between 0 and 5 degrees, which is not shown on the above graphs. However, the graphs do show two clear strong peaks, between approximately 16:05z-16:35z and 17:03z-17:32z, with a later insignificant peak. At my location on 13th November, these equate to elevations of around 10-15 degrees and 19-23 degrees respectively. The lower window is no surprise to me, agreeing well with previous results off the Moon. What is surprising is the higher window which appears to be equally as good: In the past I’ve always assumed that I might as well stop looking when the Moon’s gone above 15 degrees, but this shows that it might be worth looking again a little higher up! I shall certainly give it a try 🙂

Moonrise today was in a very favourable position for this location, in a direction I know from past experience provides good ground gain. It was also at a conveniently sociable time, which is always a bonus!

I saw on the N0UK EME chat that Bob, ZL3TY (RE57om) was active and he was kind enough to set up a sked for 07z, at which point my Moon was just starting to rise and his was setting: We had a little over ten minutes of common window.

Almost exactly on cue, Bob’s signal appeared and the QSO ended up being quite easy. I had a nervous moment when Bob continued to send “RO” after I’d sent a period of “RRR”, but signals were back up in the next period and all was ok.

So that’s my longest distance QSO (ODX) on 2m, at 18956km (or 18984km, it depends on how it’s calculated?) – many thanks to Bob for making my day. It’s going to be a difficult one to beat!

Transcript of JT65B sequences:

065700  Transmitting: JT65B   ZL3TY EI3KD IO51                         
070400  2  -24  1.9  100  3 *      EI3KD ZL3TY RE57          0  10 
070500  Transmitting: JT65B   ZL3TY EI3KD IO51 OOO                     
070600 10  -25       102  4   RO                                   
070700  Transmitting: JT65B   RRR                           (Shorthand)
070800  2  -30       103  3   RO                                   
071000 10  -24       104  1   73                                   
071100  Transmitting: JT65B   73                            (Shorthand)
071400  2  -26  2.1  108  4 *      CQ ZL3TY RE57             1  10

Hermann, DL2NUD and René, PE1L have made it to Rwanda and are active on EME as 9X0EME. After moonrise last night I decided to listen/watch on their 2m frequency for a bit of fun and immediately saw about 12 stations calling in the opposite period.

Unfortunately the frequency the 9X0EME team were using, 144.112MHz, has a couple of noisy spurious carriers here within the JT65B passband. I could see the sync tone from them at around -26, but was failing to get decodes because of the QRM. It was obviously time to kick back and watch the action, rather than join the QRO pile…

The expedition’s signal faded after the Moon went above about 6 degrees elevation, as is usual at this QTH. I knew from past experience that signals normally reach a second peak at around 12 degrees elevation and also that, by then, the mutual doppler would bring 9X0EME’s signal to a better frequency relative to my QRM.

I wasn’t disappointed! True enough, from about 11 degrees up the signal started to appear again and when I saw that a previous QSO was coming to an end I started calling. From the previous traces I’d seen from other callers, I reckoned a lot were calling with their TX set more or less exactly on 144.112MHz, so I decided to set my TX with a shift of -300Hz to put my feeble signal in “clear air” 😉

This is the resulting sequence (9X0EME in bold, EI3KD in italics):

234400 1 -31 199 3 RRR
234500 Transmitting: JT65B 9X0EME EI3KD IO51
234600 2 -25 2.5 194 3 #
234800 2 -30 191 4 RRR
235000 1 -26 2.4 188 3 # EI3KD 9X0EME KI58 OOO 1 10 
235100 Transmitting: JT65B RO (Shorthand)
235200 0 -27 2.4 188 3
235400 0 -29 2.5 186 2
235600 0 -27 0.9 183 3
235800 3 -29 182 5 RRR

The first two “RRR” received were for the previous contact. Although I was struggling to get decodes through the QRM every period indicates a decent sync detection, as shown by the DT of 2.4 or 2.5 seconds (equating to how long it takes for the signal to get to the Moon and back) and the constant DF of around 188Hz.

There was some confusion at the end because the team were operating a policy of “two periods of report and if no reply move on”, which is very reasonable for a much sought-after expedition during the initial pile-up. At 23:58 a message appeared in the N0UK EME chat asking me to try again later because they hadn’t seen my reply – but at the same time I was receiving a clear “RRR”? It turned out that they’d typed the message and in the time it took to send to the chat had seen my “RO” – they had already started sending “RRR” which I then received straight away! So the QSO was completed by the skin of my teeth, for what is probably an EI-9X first on 2m (completed at 25/06/13 23:59z).

Thanks again to “The Team” for a brave and adventurous expedition – best of luck and safe journey home.

After two weeks of trying, I finally managed to work 9G5EME on 2m, via moonbounce (EME)! The contact was completed at 23:00z on 26th April 2013, for an EI-9G first.

I have to admit I hadn’t really tried too hard at the start of Team Athletico’s expedition, presuming that it wouldn’t be possible to work them with my system (see below). However, after I’d heard the first signals I became seriously motivated! I can only use EME at moonrise, because I have no elevation control on the antenna and moonset is always obscured by a very electrically noisy building, but I listened at every opportunity.

My system is very marginal for EME, with an 11el F9FT at only 6m a.g.l., a fixed elevation of 10 degrees, 400W from a Beko HLV600 sspa, and an SSB Electronics SP-2000 masthead preamp. Past experience has shown that the best signals often occur for me when the Moon is at around 3 or 4 degrees elevation, and then again at around 12 or 13 degrees. Due to the local topography, my largest ground gain occurs when the Moon rises over the north-eastern horizon: I thought the early days of the expedition (when the Moon had a high northerly declination) would be my best chance because of this, but it turned out that I effectively had no common window with 9G at that time because trees were attenuating the moonrise path at their end.

So, apart from a few periods of signals from 9G5EME some days earlier, I had no success up until the final day of the expedition. Even on the final day, with the Moon passing through my first antenna null at 5 degrees elevation, there was nothing other than fleeting (and then lost!) signals both ways. Tom, EI4DQ, was also QRV, and had exactly the same experience. Stress!

I knew that I had one, final, chance. As the Moon starting rising up towards my second antenna peak, there it was – a trace! And then a decode!

225000  1  -26  2.4   57  3 *      CQ 9G5EME IJ95            0  10

Ok, quick, get into gear and start calling them. Next period:

225200 0 -26 2.6 54 4

No decode, damn! Still seeing a good sync at -26, keep going… Next period:

225400 1 -27 2.5 54 3 #

Gah! Still no decode, sync is ok but getting weaker, could be disaster… Next period:

225600 1 -26 2.6 54 3 # EI3KD 9G5EME IJ95 OOO 0 7

Yes, a great decode!!! But the QSO is not yet complete: Next, I have to send a R-Report. I start transmitting “RO”. Next period:

225800 0 -27 3.2 51 12

This isn’t easy… again, no decode… come on! Next period:

225800  0  -27  3.2   51 17

It’s not looking good, signals are getting weaker and the QSO is still not complete. But if I look hard enough, I can convince myself that I can see, visually on the trace, what looks like the tones for “RRR”. It’s not decoding but stick at it! Next period:

230000 2 -30 52 3 RRR

There it is! The QSO is complete, although I start transmitting “73” as a formality. On the next period I visually see the tones for 73 coming back on the trace although it doesn’t decode, but it doesn’t matter. Here is one very happy ‘3KD 😀

Many thanks to Team Athletico: Eltje PA3CEE, PE9DX Johan, and PE1L Rene for a fantastic expedition, and for knocking 2 years off my life expectancy…