Wednesday, 30 September 2015

23cm EME revisited

After the best part of three years QRT on 23cm EME I thought that with the dish relocated to a more favourable position in the garden and yet another dead wych elm tree removed ( Ivy is still a good 'noise generator!)fom the garden boundary, i would have a listen during the September 2015 ARRL all mode EME contest.
In total, over the two days and also Monday evening, I decoded or heard ( on CW or SSB) more than 20 different stations, with the best being JA6AHB. Signal levels ranged from -5dBJT down to around -22dBJT.
I looked carefully for VK5FA who was running just 40W but even though I knew he was there when working other Europeans,  I could not get a JT65C decode from him. Maybe next time. Andy is located in Adelaide and as I am going there next month I thought it might be nice to work him or at least give him a signal report.
Today I started to terminate my 14m length of LDF5-50 transmit cable. The cable runs from the shack to the dish so that the amplifier can stay in the warm, dry, shack, as previously. Although the cable loss should be 0.8dB at 23cm, the measured loss on my network analyser stubbornly refused to go below 1.3dB. I suspect the extra loss is from the old connectors I am using. With 200W in the shack this means I will just about achieve 100W at the feedpoint wih the additional loss of the short patch lead around the rotator. That is a smaller transmit signal than I used to achieve with the dish closer to the shack using around 8m of 5-50.
If I am going to take this seriously I will have to think about moving the amplifier closer to the dish. Maybe even run 300W in the old Storno case as I had previously planned to do.
The VLNA preamp performance is quite adequate and gives a sun to cold sky ratio closer to what I would expect than I saw previously.

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