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
g4eml
Posts: 305
Joined: Thu Apr 26, 2018 9:36 am

Re: Extending Langstone to include 10GHz

Post by g4eml » Sat Oct 03, 2020 9:37 pm

Hi Barry,

At present only the 5th harmonic can be selected for receive. As the top frequency for the Pluto is 6 GHz that sets a limit of 30Ghz.

Probably the only practical use for the 24GHz mode is as a test source or local monitor receiver. I suspect it would need a lot of external gain to make it into a usable transceiver.

Colin.

G8AGN
Posts: 34
Joined: Mon Mar 05, 2018 1:41 pm

Re: Extending Langstone to include 10GHz

Post by G8AGN » Sun Oct 04, 2020 11:22 am

Hi Colin

I notice that on the 24GHz band setting, x2 can be selected on TX as well as x1 and x5 but only x1 and x5 on RX.

This morning I unearthed my very old WB 24GHz rig based on a Plessey Gunn diode module and fired that up.
As you can see in the photo, the Gunn is not very stable (as expected but OK for WB) and is low in frequency but at least I can now see a signal on Langstone at 24GHz. That's today's progress.

73 Barry, G8AGN
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g4eml
Posts: 305
Joined: Thu Apr 26, 2018 9:36 am

Re: Extending Langstone to include 10GHz

Post by g4eml » Sun Oct 04, 2020 11:42 am

The X2 selection on transmit is to support the Hydra 10GHz module by OE8FNK. that has a simple doubler for transmit and a PLL satellite down converter for receive. Because it doubles the output frequency of the Pluto it cannot be used for SSB and FM has double the deviation. This is the main advantage of using the harmonic mixing method, SSB and FM remain usable. The disadvantage is that the output power is much lower.

G8AGN
Posts: 34
Joined: Mon Mar 05, 2018 1:41 pm

Re: Extending Langstone to include 10GHz

Post by G8AGN » Mon Oct 05, 2020 7:49 am

I have now tried receiving the second harmonic of an Elcom 1295 synthesiser running at 12.240GHz. This is normally used to provide a marker for 122,4 GHz for use with the VK3CV 122GHz transceiver boards. The frequency multiplication is done using a double diode mixer chip from an old SatTV LNB soldered across a piece of 141 semi-rigid coax.

As expected, this signal is very stable!

73 Barry, G8AGN
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g3yjr
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Joined: Sat May 23, 2020 1:37 pm

Re: Extending Langstone to include 10GHz

Post by g3yjr » Thu Oct 15, 2020 1:35 pm

That does look astonishingly stable!

73 Graham

G8GKQ
Site Admin
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Re: Extending Langstone to include 10GHz

Post by G8GKQ » Sun Oct 18, 2020 4:40 pm

Thanks to Colin for some outstanding research on this capability.

I have just added a "5th Harmonic" mode to the Portsdown Signal Generator. Described here: https://wiki.batc.org.uk/Portsdown_4_Signal_Generator

Dave, G8GKQ

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