The recent Martlesham microwave round table on the 9th November 1997 saw the largest collection of amateur 47GHz equipment ever seen together in the UK.
From the UK, there were eight different sets of gear, three narrowband, and five wideband. These are shown in the picture below, together with most of the operators.
First the equipment, from left to right: G4DDK NB (on tripod), G3LQR NB, G8AGN WB (dual horns), G3FYX WB (with calibrator/horn at side), G0CZD WB (in front), G8KMH WB (dual horns), G4KNZ WB (in front of folder), no antenna, and G3PYB NB (dish in mini-tripod).
Next the operators: standing from left to right, are Sam G4DDK, Simon G3LQR, Roy G3FYX, Martyn G0CZD, Steve G4KNZ, and Lehane G8KMH.
There are now a total of 12 stations in the UK, either with completed equipment, or under construction. Four of these are running narrowband cw or ssb, ranging from 0.1mW to 15mW output, and the remainder are running wideband FM equipment, all with 100mW Gunn sources. Cross-mode operation is usually possible since those with narrowband usually also have a receiver with a wide tuning range with a wideband FM detector (eg broadcast FM).
Freddie ON6UG was also at the round table, with his 47GHz "Just In Time" narrowband transverter. This is the DB6NT subharmonic mixer driven by a 23.5GHz local oscillator, and despite giving out only 0.1mW, has been heard over a 90km path.
The UK DX record on 47GHz was recently increased to 65km by G3FYX and G4KNZ, on the 25th October.
G3FYX operated from Charterhouse (IO81PH) and G4KNZ operated from just south of Hackpen Hill (IO91CK). The path from the car park at Hackpen to Chaterhouse passes directly over a hill in Bath only 30m below the path (4/3 radius), and with Bath University buildings on top, which was why G4KNZ took some trouble to drive over 1km South along the ridgeway, to be sure of an unobstructed path.
Both stations were using 100mW Gunn sources, cross couplers and diode receive mixers. G4KNZ was using an 18 inch dish, and G3FYX a 14 inch dish. As with previous tests, the antennas were aligned using 24GHz first - a WG22 feed allows this.
The tests were started at 0900 GMT, on a cold clear frosty morning with no wind. At first, signals seemed not so strong, possibly due to lingering mist on the path, but by 0945, good stable WB FM speech signals were exchanged both ways (55 and 57 reports). G4KNZ estimated G3FYX was about 12dB above minimum detectable.
The UK DX record had stood at 13km for some years, set by G3HBR and G3HBW, until in the last two years, it has been progressively extended as follows:
With the construction of several sets of narrowband equipment, which extends the path loss capability, in due course, contacts over 100km are anticipated.
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