Portsdown 4 - First build now available

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
radiogareth
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Re: Portsdown 4 - First build now available

Post by radiogareth » Fri Aug 21, 2020 7:31 pm

A cheapo (£5 delivered) Picam plumbed in this evening using a 12" ribbon, Pluto to Pluto across the shack on 3.4GHz. Glaring lights are very bright LED so I can see what I'm doing,
Lucky to have a working Purple Stealth amp for the band too and a duplexer that should help the front end.
Next question is a suitable gain antenna. Bi-quad perhaps? Flat-plate from yagi.pl?
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Gareth

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G1LPS Terry
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Re: Portsdown 4 - First build now available

Post by G1LPS Terry » Sat Aug 22, 2020 3:15 pm

Hi Gareth
Ive just changed from a 20db panel to a 91 element loop yagi on 3.4ghz.
Big difference and now hear 6 uk beacons from up here in IO94EQ
Used the JVL calculator. The antenna required no tune when checked on a MiniVNA 2

Here's my setup / loop yagi dimensions
https://g1lps.com/9cm/

Terry

radiogareth
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Re: Portsdown 4 - First build now available

Post by radiogareth » Sat Aug 22, 2020 6:10 pm

Very helpful Terry. Another build project for the autumn and winter :-)
Gareth

2E0NJT
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Re: Portsdown 4 - First build now available

Post by 2E0NJT » Sat Jul 24, 2021 7:46 pm

Having built a portsdown 4 i found some problems on the software i bought a good quality sd card and loaded rasbarian connected it to the network and ran the script to start the software download, it all went ok or seemed to the standard menu appeared on screen but a few funny things occured when trying out some of the settings.
On the band viewers you get the grid and the trace appear but also loads of code running through it and i could not get a c920 camera to work with it, so i decided to try loading it again but this time i plugged all the usb hardware in while running the download (not sure if thats needed) and when it finished everything works so much better cameras all fine and now that my minitione is fixed it loaded the beacon from QO100 perfectly ive checked out the transmit side of the lime mini to my marconi 2955 at several frequencies it seems to produce about 36mw at 145 mhz.
I did notice the software version had changed from the previous version i downloaded perhaps these bugs were already solved.

I have a question about firmware for the lime mini at the moment im only building this to work through the satellite at 2.4ghz and 10ghz direct i will add other things later do i need to use the std 1.30 fw in the lime or upgrade it to the dvb fw to be able to transmit video.

Nigel

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Re: Portsdown 4 - First build now available

Post by 2E0NJT » Sat Jul 24, 2021 7:52 pm

Sorry forgot to ask does the wifi work on the raspi 4 i tried logging on to is and using sudo raspi-config and then in the menu i setup my wifi connection and that didnt work and if you press the wifi button on the portsdown menu the screen is blank at the top with exit at the bottom so cant set it up there.

Nigel

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Re: Portsdown 4 - First build now available

Post by G8GKQ » Sat Jul 24, 2021 8:43 pm

Hi Nigel

The quality of the SD Card does not matter - the exact timing specification does. That is why we recommend the red and grey SANDisk Ultra UHS1 cards. I've seen problems with both Kingston and Samsung cards - the Raspberry Pi is very fussy and does not like those.

For QO-100 I recommend the 1.30 firmware for the Lime Mini. You only need the DVB firmware for high SRs (4000 kS).

Many people have used the WiFi, but it is not something that I recommend or test. Particularly when transmitting to QO-100.

Dave

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Re: Portsdown 4 - First build now available

Post by 2E0NJT » Sun Jul 25, 2021 9:23 am

Thanks Dave,

I did use the card you recommend perhaps there was a glitch on the download, at least its all working now.

With regards to wifi just wanted to be able to update from the shack but i will have to just use the link indoors.

Thanks again.

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Re: Portsdown 4 - First build now available

Post by G8GKQ » Sun Jul 25, 2021 9:48 am

OK Nigel

Using WiFi is the least reliable way to perform Portsdown (or Ryde) updates and, in my view, asking for trouble.

I would strongly suggest running a semi-permanent Cat 5 cable from the house to the shack; the effort will pay off in the long run.

Dave, G8GKQ

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Re: Portsdown 4 - First build now available

Post by 2E0NJT » Sun Jul 25, 2021 12:25 pm

Dave

Not possible at the moment as im building a side extension but eventually i will do just that.

1.2 m dish is above the garage at the moment so i can adjust it and see in the shack but thats moving later as well.
Not bad for £15 new.
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Cheers
Nigel

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