Brian GM8BJF & Pete GM4BYF
At the LRS meeting at the BHH on 6th October 2021 Pete GM4BYF, assisted by Brian GM8BJF, described how they implemented VK3CV duplex FM transverters for the extreme microwave band 122GHz (2.5mm wavelength) and achieved the first QSOs on this band between 2 stations in GM and between G & GM in July 2020. During the meeting they provided a live demonstration of the equipment in action. The presentation was also viewed remotely by four members via Zoom.
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The VK3CV transverter circuit board for 122GHz to 144.4MHz..
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Test path between Braid Hills Road (GM4BYF/P) and Blackford Hill Observatory car-park (GM8BJF/P)
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A section of disused railway line crossing the border near Selkirk was chosen for the GM-G path.
Ist G – GM QSO: G4BYF/P looking across the border to (DX) GM8BJF/P
Please go to Brian’s website to view these videos shot during the QSOs:
https://gm8bjf.joomla.com/2-uncategorised/23-122-ghz-activities
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Quadrature Combiner circuit designed by Mark GM4ISM (Larkhall).
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Frequency display showing transverter 122GHz duplex Tx/Rx and 144.4MHz output to transceiver.
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Remember, the output power is only 0.5mW !
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UK frequency allocations in this frequency region are very close to water and oxygen!
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Brian GM8BJF (L) in garden of Pete GM4BYF QTH (“Bates Motel”)
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Spectrum analyser used to measure signal bandwidth etc.
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Brian GM8BJF adjusting things at his end.
Pete GM4BYF measuring things at his end.
Looking into a 75 to 125 GHz waveguide port on a spectrum analyser harmonic mixer. (GM8BJF).
GM8BJF 122GHz waveguide harmonic mixer re-purposed as a X10 frequency multiplier from 12.2GHz to 122GHz. This makes a useful weak signal source for dish fiddling.
GM8BJF hand-made feedhorn for 122GHz according to the VK3CV design.
(GM3BCD-SK would have been proud of him)!
After their presentation Brian and Pete were thanked by LRS President Colin GM4HWO.
See also early report on this project (Click).
PS – a visit to the QRZ.com page for Andrew Anderson VK3CV is well worth it – very impressive!
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