At the meeting of the Lothians Radio Society on 28th November 2012 Brian Howie GM4DIJ talked on "Getting Started on Six Metres". He covered the history of the availability of the 50MHz band to amateurs, the equipment and aerials necessary to operate it, and the many types of propagation which can occur on "the Magic Band".
The Six Metre Band is not known as the "Magic Band" for nothing. It is a low VHF band at 50MHz with all the characteristics of a VHF band, low activity, noise and weak signals. But especially during the summer months, and at times of high solar activity, the band can open up to all over the world and it is possible to work very long distances with modest equipment. Since the UK and most of IARU Region 1 obtained full access in 1986, activity has soared and it is now easier to set up and get started on the band.
The 5 metre band (56MHz) was taken from UK amateurs in 1949 for use by the 405-line BBC televison service. In 1957 special permits were issued to amateurs to operate on 50MHz outside of TV hours during the IGY - International Geophysical Year - and more generally later. The GB3SIX beacon in Anglesea operated outside of TV hours initially and encouraged cross-band QSOs with North America. In 1983 the RSGB coordinated a list of 40 amateurs granted special 50MHz permits, including 10 GMs: GM3DOD, GM3OBC, GM3WCS, GM3WOJ, GM3ZBE, GM4FDT, GM4FZH, GM4DIJ, GM4IGS, & GM4IHJ. After the closure of 405-line TV, the 50MHz band was opened to class A licensees in 1986 and Class B in 1987. Power and aerial restrictions were lifted in 1997.
The characteristics of 6m are usually those of a low-VHF band: tropo not as good as 4m, ducting very rare, sporadic-E very frequent in the summer months, aurora with less Doppler distortion thna 4m or 2m, good meteor scatter - longer than 4m or 2m. F2 ionospheric propagation only occurs a for a few years around sunspot peaks.
Initially in the UK, 6m equipment consisted of home-brew receive converters and transverters. Brian showed some of his early equipment. Then commercial transverters became available from Spectrum Comms, Mutek, Microwave Modules, RN Electronics etc. When the 6m band was incliuded as standard in later HF transceivers, the transverters became available on the second-hand market at attractive prices. High-power linear amplifiers are also now available. There is a wide range of beams available. Brian showed a photo of the M² 6M11JKV 11-element wide-space yagi which is 69 ft long and provides a gain of 16.10 dBd for only $1480 (!) However, the characteristics of 6m mean that simple aerials can often perform quite well - a single Delta-Loop was shown at the meeting, made from PVC piping and wire.
Current SSB/CW operation on 6m is relatively low except during contests and Es, F2 and auroral openings. It is worth monitoring the ON4KST spotting cluster for activity. Meteor-scatter and tropo activity using digital modes such as JT65 and FSK144 is popular in mainland Eu. There is an FM repeater GB3SL in Central Scotland but activity is believed to be low, as is FM-simplex operation here.
Contests generate a lot of activity - UK Activity Periods, 1st-50MHz Contest (April), 50MHz Trophy (June), VHF NFD (July), 50MHz AFS (Nov) and Christmas Cumulatives. The LRS is well-equipped for 6m operation with a 9-element wide-spaced yagi (which can also be re-configured for 4m) and usually does well in VHF NFD from our portable site near Gatehouse of Fleet.
As a bonus, Brian also talked briefly about the Graves Radar in France, which operates on 143.050 MHz. He demonstrated that it is possible to receive its radar pings from the moon using simple equipment.
See RSGB RadCom 11/2012 p.64, and http://www.itr-datanet.com/~pe1itr/graves/
GM4DIJ Licence Notice of Variation to operate on 6m in 1983.
Cycle 21 Crossband Award received by GM4DIJ for Transatlantic cross-band operation.
6m Transverter built by GM4DIJ to a Practical Wireless design.
Commercial transverters were offered by a number of suppliers.
They are now available second-hand at good prices as transceivers have incorporated 6m as standard.
Most modern HF transceivers include the 6m band as standard.
There are plenty of high-power 6m linear amplifiers on the market.
An 11-element wide-spaced beam for 6m - with a boom-length of 69 feet!
The antenna stack of top 6m DXer K1WHS
But simple aerials such as the Delta-Loop can sometimes work wonders on the "Magic Band".
Brian put this Delta-Loop together at home, the night before his talk, using PVC pipe and wire.
Contests are among the busiest times on 6m.
The LRS usually does well on the band in VHF NFD.
Payback - DX QSL cards received by GM4DIJ for QSOs on 6m
As an encore, Brian gave a demonstration of the reception of Graves Radar echoes from the moon and meteors.
(Photo courtesy of RSGB RadCom, 11-2012).