March/April 2009
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E51EME Summary After Lance and Karen missed their flight from LAX to RAR they unexpectedly ended up in ZL ... actually it was a real bonus to be given the opportunity to see another country! We took them on a short tour of the highlights  ZL1RS QTH :-P before driving down to Auckland to catch the flight to Rarotonga in the south Cook Islands that night. Upon arrival in Rarotonga we set up Lance's 6M antenna first because he could operate effectively on 6M at new moon. The 2M station went together the following day with the antenna array mounted on the balcony of the holiday rental home at about 8m above the lagoon level. I commenced operation at the next moonrise after new moon.  Unfortunately no signals were received during the first moonrise period due to an intermittent RCA connector on my interface box not supplying power to the masthead relay. The coax relay in the masthead box was permanently switched in the "TX" mode. After tearing the whole RX chain apart the simple problem was finally found and I started to work some stations ... ... but the RX was still down. You know there is something wrong when the "big guns" who are normally -15 at home are only coming in at -27!! The preamp was the culprit this time. It appeared to be providing gain, but it was "all noise"! In order to replace the preamp with the spare one I had to remove the masthead box and install the spare preamp at the shack end of the feedline. This compromised the RX performance, but not by much because the main feedline loss was just 0.5dB (10m of LMR-400 coax). Both Lance and I noticed some difficult conditions on both 2M and 6M at moonrise. Signals varied wildly and the expected ground gain was masked at northern declination by thick vegetation down the beach front. On 2M I could usually see strong signals from 0-2 degrees, but between 3 and 10 degrees signals were very erratic. Lance was seeing a similar effect on 6M. We had several theories for this ... sharp ground gain lobes and nulls due to the 2M array being 8M above the lagoon level (but this does not explain the same effects on 6M where the antenna was only just over 1WL high), ionospheric absorption, ionospheric diffraction or scattering due to highly charged ionosphere at the tropical latitude (-21S), or tropo ducting reflecting the signal away at low elevations. Unfortunately the common moon window to Europe where many 2M EME stations are located was at our moonrise which occurred during the local day time hours. As a result, this window was severely disrupted by the difficult conditions, so I lost many QSOs. I will keep this tropical region propagation effect in mind when planning future dxpeditions!  When the moon was above 10 or 12 degrees of elevation the signals tended to stabilise and my own echoes also became quite consistent. I worked many stations very quickly and easily when the moon was well elevated.  The array was finally moved off the balcony location down to ground level for the last two days of operation. This was done in an attempt to broaden the ground gain lobe and get the advantage this can bring as was seen at A35RS. The new site also gave a better shot to moonset that was otherwise blocked by the house when the array was on the balcony. The effort was met with moderate success ... still some severe fading, but the ground gain lobe at moonrise seemed to be wider and more effective with the array at a lower height. I will keep this array height factor in mind when planning future dxpeditions!  70cm QRPp EME ... 15 element YU7EF yagi on a 3.4M wood boom (a length of very old decking timber found in the bushes!)  The Mirage D1010 was mounted at the feedpoint to reduce feeline loss! We even made the local news paper!See you from "the next one" ... 73, Bob ZL1RS/E51EME E51EME results, 27 March - 06 April 2009 :145 different callsigns contacted via 2M EME
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