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

Wednesday, 29 July 2015

First 144MHz EME QSO


After spending much of today removing my 4/6m yagi from the mast in order to put the 144MHz yagi back up I was rewarded with my first 144MHz EME QSO! 

Almost predictably the QSO was with I2FAK. Using 200W of JT65b to a YU7EF and one of my PGA144 preamps, Franco reported my signal at -21dB and he was up to -15dB with me, averaging -18dB.

I also saw an S5 calling G0GXT and PA5Y working I2FAK.  PA5Y would have been workable although his direct signal was close to and many dB stronger than the reflected signal.

The big change from previous attempts at EME on 144MHz is that the YU7EF now has a straight dipole rather than the folded dipole that had caused me so much trouble with a poor match. I have a second to add to the array at some stage.

The moon was one day past lowest declination, so at the time of the QSO, the elevation of the moon was about 15 degrees at an azimuth of 150 degrees. I suspect lots of ground gain this time!

That is now 4 bands on which I've had EME QSOs (2m,  23, 13, & 6cm) and I've heard signals on 9cm and 3cm.
Hopefully I will add these two latter ones as worked in due course and add 70cm at some stage.

Sam













Friday, 24 July 2015

Amsat Colloquium

Mainly getting ready to go to the Amsat Colloquium in Guildford tomorrow.
Early start but that may mean braving the stormy weather due to pass over this area tomorrow morning around the time we are due to start out.........

I met up with VK5DK from Mount Gambier, South Australia, today. Colin is visiting the UK with the Victoria State over 70s cricket team. Their game in Ipswich, today, almost didn't happen due to rain. But they managed to get in a few overs before calling it a day! Colin and I had the chance to chat for an hour or so. Last time I saw Colin was in South Australia some 6 years ago.

Although Mt Gambier is actually in South Australia, the tour captain told me they designated anything east of the Murray River as still in Victoria. That way they were able to include two people from Mt Gambier.  I guess it is getting difficult to find enough players over 70 to include in their touring team!

Sam




Friday, 10 July 2015

More EME dish

Whilst writing this morning's blog I realised I hadn't updated the EME dish story.
I have now used the 2.3m dish to receive the the DL0SHF 3cm beacon reflected off the moon. I've also received JT4F signals from G3WDG at around -6 dBJT ( dB below 0dB in 2.5kHz)
This is quite good but several dB lower than I would have expected. My tracking is still being refined. 

After my initial euphoria at being able to find moon noise, later tests showed it to be a lot more difficult to find when the moon was at low declination and was close to trees etc, possibly indicating a bit more  ground noise that there should have been. Whilst the moon was at low declination I took the opportunity to change the feed for the 23cm one to check this was still working. It is three years since I last made a 23cm EME QSO! The reason being the need to move the dish to a new location in the garden after my neighbour's extension went up and blocked my moon window from anywhere west of south. No NA stations west of the American East coast..... The new location is more prominent, but gives a longer moon window.

My attempts to improve the cage alignment seem to have paid dividends as I now get more sun noise to to cold sky on 23cm than when I was last active on the band. And yes, this is taking into account the currently higher solar flux!

Sam


Transverter follow up

I have commissioned another batch of Anglian transverters from my 'assembly' man!
Of these most will be for 2m, but a significant number will be 'uncommited' boards that can be either 2 or 4m ( or any other band between 220MHz and 30MHz).

As the noise problem on 4m hasn't proved to be a big problem when beaming between east through west it has not impacted my SpE activity on 4 or 6. 
DXCC and locator scores have been steadily increasing.

I am off to the Finningley Microwave Round Table on Sunday. My intention is to take a small number of various kits including the very last one of the current batch of Anglian 144MHz transverters. I will also take PCBs and devices for sale as spares or as required. As always, I will be taking the ever-popular WA5VJB PCB antennas, covering all frequencies from 400MHz to 25GHz.

Hoping to see lots of microwavers at Finningley on Sunday.

Sam