Thursday, 27 August 2015

Clearing the bench

I have decided it is time to clear the workbench. I am down through the first (top) layer and starting to find the interesting stuff like coax adapters, tools and missing components.
I have decided that it is time to change the 15 year old + anti-static matting and the heat proof matting used when seam soldering PCBs into tinplate boxes. It's looking like a run to Rapid Electronics tomorrow.... First I have to reach that layer, though!

I'm hoping a clean bench will provide the encouragement I need to get on and complete some of the current ( stalled) projects.

What prompted this?
Acquiring more parts yesterday when the local computer shop announced it was closing this week and a number of PC processor heatsinks and cooling fans were made available for a small donation to the local sea rescue service. Also the imminent arrival of more amplifier PCBs and reels of components.
I also need the room to finish off the new 24GHz transverter.

Time to go and start digging, sweeping, examining, storing and throwing out, again.
Bye.




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


Wednesday, 5 August 2015

9cm EME

I spent a bit of time today trying to figure out how to mount my 9cm RA3AQ feed to the cage on my EME dish.
This evening I managed to mount the feed to a surplus aluminium box chassis of the right height to bring the centre of the feed in line with the centre of the dish.
Tomorrow I plan to add the 9cm LNA and feed the 9cm signals back to the transverrter in the shack through a length of LMR600 that is already installed in the duct.
This weekend has been designated as the 9cm Activity Weekend (AW) when all those with suitable equipment for the band can make contacts, do measurements and generally check out the system without the inevitable pressures of a contest or new DXCC/Locator challenge!

Sam