Extending Langstone to include 10GHz

Forum for discussion about the Langstone Microwave Transceiver that shares some features with the Portsdown. Wiki: https://wiki.microwavers.org.uk/Langstone_Project
radiogareth
Posts: 723
Joined: Wed Jan 06, 2016 9:46 am

Re: Extending Langstone to include 10GHz

Post by radiogareth » Tue Apr 27, 2021 12:43 pm

I'm playing with a pair of Langstone (portsdown) TXRX checking best solutions for initially 3.4GHz and then 5.8GHz, maybe onward upward to 10GHz.
From basic tests on the bench with a switched attenuator I think the S meter is about 6dB per S point.
I'm comparing a variety of aerials, using the Pluto rubber duck as a base (I know its not much good) then a PCB LPY, cantenna, double Bi-quad, 4x4 patch arrays (ex WiMax units) and finally 3 different dishes all fed with the nominally 6dBi LPY PCB aerial. (BSkyB, 24" FD 0.3 and a 26 " diameter FD 0.412
Any advice on getting the most meaningful readings from my receiver?
Thanks
Gareth

radiogareth
Posts: 723
Joined: Wed Jan 06, 2016 9:46 am

Re: Extending Langstone to include 10GHz

Post by radiogareth » Tue Apr 27, 2021 2:59 pm

So investigating RX gain, I turned off 'auto' and then with a combination of lowering the TX power (as a CW beacon with a 120 second carrier) and RX gain got S3 reading with the Pluto rubber duck at each end.
Pluto RD = S3
LPY= S4 (it has 6dBi 'average gain' apparently)
Cantenna S5 (just)
Dual Biquad (homemade from PCB & wire) S5.5 (an 'easy S5').
4x4 Patch S6 - just
BSB Offset dish fed with LPY, both used horizontally S6, ever slightly better than the 4x4 patch
2' diameter dishes with different F/Ds, hand aimed and optimised - an easy S6
All very unscientific but pretty much what I expected.
Had a quick play on 5.760 too while the gear was out in the garden.
Pluto RD - S6-7
BSB Dish and LPY S9+2dB
Gibeon 24HV flat plate aerial from yagi.pl S9+10
Comments welcome....
Gareth

g4eml
Posts: 417
Joined: Thu Apr 26, 2018 9:36 am

Re: Extending Langstone to include 10GHz

Post by g4eml » Tue Apr 27, 2021 3:33 pm

Hi Gareth,

As you have found, the Langstone S meter is calibrated to about 6dB per S Point. It indicates the highest signal level inside the receiver bandwidth.
You are correct to turn off the Auto RX gain if you want to make measurements. That reduces the dynamic range of the receiver but stops the Pluto from adjusting its gain automatically.

Maybe another way of making the comparative measurements would be to adjust the TX attenuator to give the same reading on the S meter. The change in attenuator setting would then give a good indication of the relative antenna gain.

Colin.

G7JTT
Posts: 268
Joined: Fri Jun 10, 2016 5:05 pm

Re: Extending Langstone to include 10GHz

Post by G7JTT » Thu Jun 10, 2021 10:27 am

Not sure if these have been spoken about before for doubling up to10GHz ?

https://www.ebay.co.uk/itm/Frequency-Mu ... 890.l49286

73 John G7JTT

g4eml
Posts: 417
Joined: Thu Apr 26, 2018 9:36 am

Re: Extending Langstone to include 10GHz

Post by g4eml » Thu Jun 10, 2021 1:14 pm

It is a passive device and needs a fairly high input level. So it would probably need an amplifier before it. Output power could then be around 0dBm.

Of course multiplying is only good for CW or FM modes.

Colin.

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