GB3EY Repaired

Locator: IO93WT
Location: Hull, East Yorkshire
G3GJA
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Joined: Sun Nov 20, 2011 3:44 pm

GB3EY Repaired

Post by G3GJA » Tue Oct 29, 2019 5:44 pm

GB3EY was returned to service in beacon mode at 1530 today the 29th October.

********PLEASE NOTE THAT GB3EY IS NOW USING 2000kS/s********

Although the failure of the driver PD85004 left a chunk of carbonized PCB underneath it, surprisingly it was possible to repair the board with some 0.2mm copper sheet shims cut to fit the available space. A pair was used, with one above and one below the tab of the LDMOS device and then the whole lot was heated until some solder between the shims flowed.

A 5mm hole was drilled through the sandwiched sheets to take an M5 bolt. A chunk of Maplin heatsink left over from another project was drilled and tapped to take the M5 bolt on the other side of the PCB. Once assembled with copious amounts of heatsink paste the steel bolt was found to take the heat from the PD85004 surprisingly well. A small 25mm fan was attached to the heatsink to increase it thermal capacity. Hopefully, this will last a little longer!

The gain of the driver is within half a dB of the original so the grounding / heat removal properties of the copper shims seems to have worked and the shoulders of the 225mW output are still more than -50dBc.

Reports welcomed!

Clive G3GJA
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Wolfie G8VAT
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Re: GB3EY Repaired

Post by Wolfie G8VAT » Tue Oct 29, 2019 7:52 pm

I'll have a quick look tomorrow Clive.. But I'm just about to commandeer the Alfords magmount for something else (short term).. It will return to civvy street weekend of the 9th..
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Re: GB3EY Repaired

Post by Wolfie G8VAT » Thu Oct 31, 2019 10:33 pm

I still have the magmount and I'm afraid I have seen nothing over this way Clive, not a peep.. zip.

I visited all the places I previously visited on the work journey and there's nothing at all. Nothing around home either I'm afraid.
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Graham G8VAT

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Re: GB3EY Repaired

Post by G3GJA » Sat Nov 02, 2019 1:56 pm

That's weird. I can't explain why that should be, although Richard G4YTV has suggested that it might be due to the slight tilt on the antenna to the East. At 25m it's only just discernible from ground level and would have been the same as when the antenna was at 14m when you could see it. The signal across the east of the coverage area is good.

I would have thought that an antenna with 6dB gain over a dipole would not have such a restricted vertical aperture as to completely cut off signals in your direction. The downward tilt from the EY antenna to your QTH is -0.39 degree so as long as it's reasonably vertical you should see it.

Perhaps the Fresnel effect was helping when at 14m and has less effect at 25m? I presume you have tried the receiver before on 2MS/s signals?

I think some field tests are needed. Somewhere I've a got a Severnside antenna that might do for some /p checks when coupled with a G4DDK pre-amp and the Bravebox monitor.

Clive

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Wolfie G8VAT
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Re: GB3EY Repaired

Post by Wolfie G8VAT » Sun Nov 03, 2019 9:55 pm

I haven't Clive, excuse me I forgot the 2MS/s part and will need to change the settings.. Duh!

However I'm off to colder climes for a few days and the magnet is now a stable camera mount.. I will be back late Thurs..
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Graham G8VAT

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Re: GB3EY Repaired

Post by G3GJA » Mon Nov 04, 2019 10:00 pm

That will be the problem then Graham. I've just dug out my Bravebox and initially got nothing too.

The 'found signal' presets stored in its memory can't be edited (or at least I haven't worked out which part of the manual tells me how to do that!) so I have got mine to rescan and it's come up with 95% strength and 85% quality on EY.

I got a report from Bob G7AVU, who shouldn't be able to see it at all, and it's pretty much the same as it was when it first came on at full height. Tony G0AZQ at Nafferton was having difficulty but I think that is due to issues at his end. Richard G4YTV reports normal signals at his QTH.

73

Clive

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Wolfie G8VAT
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Re: GB3EY Repaired

Post by Wolfie G8VAT » Fri Nov 08, 2019 10:52 pm

I'm back now but haven't had time to play just yet, however tomorrow is free and I believe better weather (well it can't be worse)..
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Re: GB3EY Repaired

Post by Wolfie G8VAT » Sun Nov 10, 2019 1:15 pm

Yep, EY is there Clive, I only had time to check in a couple of locations, but looking good so far.

Why the reduction to 2M/s?
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Graham G8VAT

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Re: GB3EY Repaired

Post by G3GJA » Sun Nov 10, 2019 5:45 pm

That's good to hear Graham. I also heard from Tony G0AZQ today and he's now seeing it too although he doesn't know why he wasn't able to see it earlier. I'm just wondering whether he has one of those Wimo antennas that get water in the driven element. He says he's got a 2:1 SWR but I would be worried about that.

2MS/s is being recommended by G8GTZ with his ETCC rep for ATV hat on. There is a 3dB advantage apparently, although I haven't been able to confirm that, and there is a significant bandwidth reduction. With the pressure on 23cm coming from Galileo it is thought that we should be as economical as possible with the bandwidth. The truth is that with the more advanced codecs now in use and the DVDS-2 modulation schemes it's possible to get much more through less bandwidth.

73

Clive

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keng8vdp
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Re: GB3EY Repaired

Post by keng8vdp » Mon Nov 11, 2019 10:44 am

Receiving great in Barnsley

https://youtu.be/kBvf-Zj4Q2o

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