Sunday, 9 August 2015

More 9cm EME

Having built a new VLNA9 to replace the faulty one I was trying to use I started to get sensible results using my 2.3m dish on 3400MHz EME.
Sun noise was 12dB above cold sky and moon noise 0.35B above cold sky. These numbers are averaged from a large number of readings using continuum mode in Spectravue running on my SDR-IQ.

Having found the moon I was pleased to see a digital signal from OK1KIR. It took me a while to realise it was JT4F and not JT65C. By the time I had switched modes they had gone......I only know it was them from their posting on the HB9Q logger. There is little doubt about who it was as activity at time was low.

A little later Peter, G3LTF, offered to transmit for me. At this point I realised that the transverter LO had drifted when I couldn't see Peter's CW and knew I should. I checked the beacon at Martlesham and found it was about 13kHz low of where I expected it to be. It was pretty warm in the rack by this time. With this corrected I was able to see and copy Peter's CW. Peter then switched to SSB and with a little tweaking of moon beam heading I was able to copy his SSB at up to 52. In terrestrial that would probably equate to 41, but EME (analogue) reports tend to be a little generous!

I discovered that the expected focal point for the RA3AQ feed was apparently wrong and this lost me several dB of signal until I corrected it to be in line with what I had discovered with other feeds. I still don't know why there is this discrepancy.

I may keep the 9cm feed on the dish for OK1DFC's 9cm EME portable expedition, next weekend. I might be able to get the transmit side working as well!

Sam


1 comment:

  1. Interesting fixes here. Keep up the good work! Thanks for sharing.

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