27-November-2018 SHF UKAC

There was some nice rain scatter (RS) before the contest. GB3FNY showed significant doppler rain scatter & the frequency of it shifted significantly as I swept the dish across the cloud.

All the RS seemed to have gone by the time the contest started at 7:30pm!

Conditions seemed poor. For the first time, I failed to work Keith G4ODA on 3cm. It took two goes to find Nick G4KUX.

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For the first time I worked fewer stations on 13cm than on 3cm: only six contacts.

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20-Nov-2018 23cm UKAC

Conditions were the worst I could remember on 23cm. I tried twice to work Brian GM4BYF. I could only hear snatches of him via AS (Aircraft Scatter). I failed to work him. Peter G4CLA was just audible. Gordon GI6ATZ was very up and down in signal strength, but I worked him using CW (morse code). I finished with only 21 contacts in 8 squares.

5-November-2018 opening on 3cm – G4BAO and GB3CAM

I was logged in on ON4KST’s site & saw a post on the chat from John G4BAO indicating that he had noticed a lift on 3cm. He worked Neil G4DBN who is a bit NE of here. I messaged John & he put his beacon on. I found it straight away, not far off where I thought the dish should be pointing. I peaked it horizontally and vertically.

John was 559. His signal was a bit up & down. I managed to decode “try SSB” from his morse code & we switched to SSB, where he was 53.

John & I have tried a number of times on 3cm and this is the first time we made it.

I could also hear GB3CAM a good 20+dB above the noise. This was a first too as the only beacon I have heard on 3cm up to now is GB3FNY.

The conditions didn’t last long and GB3CAM soon disappeared into the noise.

SHF UKAC 23-October-2018

Both 13cm and 3cm bands started at the same time this month, so I started on 3cm with 3W into the waveguide to the off-set horn on the 80cm dish. Peter G3PHO was the strongest I’d heard him off our reflection point before the contest. We managed some communication using SSB. He dropped a bit as the contest started, so he was my first contact using morse code/CW.

I struggled to hold the dish direction in the wind.

Nick G4KUX was my best DX, though he was the weakest I’d heard him for some time. I got six contacts in four squares, all the usual suspects.

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On 13cm I managed 12 contacts in 6 squares with an average of 112 km/contact. John G3XDY was my best DX at 237 km. I’m still using the SG-Labs 2W transverter with no amplification. One day I will have a BPF for this band and amplification!

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23cm UKAC 16-Oct-2018

Conditions were pretty average and all my contacts were in the UK. I could hear the Martlesham beacon before the contest, so that was an improvement on the September UKAC.

My best DX was Jon GM4JTJ. At first, it was very difficult to hear Jon as a local station Steve G0EAK/P was operating very close to Jon’s frequency. I worked Steve & mentioned that Jon was close by & Steve volunteered to move frequency. Steve is one of those people who places the general good of amateur radio above the competitive nature of contesting, whilst remaining a keen competitor. His good manners are part of his operating approach, making him an example to others. Thank you Steve. I worked Jon using morse code (CW) as usual.

I managed 32 contacts over 15 locator squares, averaging 125 km per contact, so reasonable, but nothing spectacular.

IO93 presents me with a wall of strong local signals to negotiate when trying to work the more distant, higher scoring stations. My old Bob Platts pre-amp must have some amount of band pass filtering in it, which is necessary here. The local Crosspool towers are very close by & chuck out all kinds of RF including TV, emergency services communications, pager systems & the output of dozens of microwave dishes in all directions. Cross-modulation products are a constant hazard, so filtering is important. A wide band “23cm” pre-amp at my station gets wiped out.

I have tuned a BPF for 23cm in case I need it. I can add relays to switch it in and out. All this would worsen the Noise Figure, so I have avoided it so far.

Davis Vantage Vue Weather Station 6250UK fault – no wind speed reading

I have had several weather stations at this location, bought via RadCom, Maplins & the like & none of them have survived long. They don’t seem to be able to cope with the weather! The latest of these is a Davis Vantage Vue. The package including the software had cost about £600, so I was hoping for a high quality station which would last many years.

The wind speed reading has shown zero for some months. I took advantage of the good weather today to take the sensor assembly down and investigate the problem.

It has been installed for two & a half years, so it is outside the two year warranty period now.

The anemometer and temperature sensor board is marked on the top:

Product: #6357OV, Model No. 6250UK, Manufacturing code MK15102 0050.

On the back is a sticker marked: 7345.405, D151012, GF026.

The magnetic sensor is marked: DAVIS 1507.

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With the case off and the other telemetry working, I tried waving quite a powerful magnet near the magnetic anemometer sensor. This produced no reading.

I stripped away the water-proofing from the sensor device. I measured the resistance across it, in situ: 830 ohms.

I put an oscilloscope across the device and spun the anemometer magnets over the device. This produced voltage kicks, both positive & negative! So perhaps the device is a Wiegland wire sensor rather than a reed switch? This suggests that the rest of the rectifier/switching circuit is working.

I checked the receiving station: it showed a wind speed reading!

I put it all back in the box: no reading! I took the lid off the box again and re-soldered the two connections to the device, using a dab of flux & a little extra solder. Still not working. Perhaps there is some sort of intermittent fault?