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The QTH is about 15 miles north east of the center of Tucson in southern Arizona, at the foot of Mt. Lemmon. About 70 miles north of the Mexican border.


The great-circle bearing to the middle of Europe is about +35 degrees, which on a radio path puts the QTH further from Europe than most of the USA, including California.

The main HF antenna is an offset rhombic wire beam, beaming in a fixed direction towards the UK. This is one half of a Laport Rhombic design from 1960, with nearly 15 dBi of gain in the right direction on 17 and 20 meters. On 20 meters the beamwidth is about 18 degrees between -3 dB points, but a feature of this particular antenna is plenty of sidelobes. In particular, there's a convenient and relatively strong sidelobe pointing towards VK, and the strong back lobe includes ZL.

I have been fairly active since September 2013 on WSPR, with a standalone 2-watt transmitter on 20 meters; in June 2017 I added a 30m 1-watt WSPR tx, given to me by PD2PCH.  The transmitters shows nicely when the band is open to a particular area.

The above WSPR image (from http://wsprnet.org/drupal/wsprnet/map   [choose "Band: 20m" and "Call: AA7FV"] ) plots all stations giving a report on the AA7FV 20-meter 2-watt WSPR signal, over about half an hour in an evening of March 2014. The WSPR transmitter gave four 2-minute transmissions during the 36 minutes. The line of stations across Europe, stretching from G4 to 4X, follows closely the great circle bearing of the main lobe of the rhombic antenna.

The main HF rig is a TenTec Omni VII.  I also enjoy using a Yaesu FT102, which I've had since it was new in 1982, and a TenTec Pegasus.  Operation is exclusively CW, when not on WSPR.  On 2 meters and 70 cm I use a Yaesu FT857D.

The picture above on the right is a view from about 16 miles NE of the center of  the city of Tucson, looking west, with the Agua Caliente Park in the foreground and the Catalina mountains on the right.  A red arrow marks the AA7FV location since 2012. The left part of the image above zooms in on the AA7FV QTH, showing in blue the approximate layout of the rhombic antenna.

My first call was G3SYS, which I have held since March 1964.  Other active calls have included F6HYR, DJ0OE and CE1/G3SYS; less active were ON8IA, OE2ZGM and YU7LBP.   I have been in Tucson, Arizona since 1986.

More material of interest to amateur radio  can be found at:  http://www.qsl.net/aa7fv/ .  It includes articles about pre-1900 developments of radio by J.C.Bose , David Hughes [PDF format] and others.

Professional career:  Degree in Physics from Oxford University, Ph.D from Cambridge University, UK. Worked as radio astronomer at radio observatories in the UK, Germany and France before joining the National Radio Astronomy Observatory (NRAO) in the USA.  Was part of the team involved in the design, construction and testing of the international ALMA radio telescope now in operation in northern Chile. Retired (up to a point) in 2012.


Darrel, aa7fv


  (Member of HSC, CWops, FISTS, SKCC & of course the ARRL)

8415442 Last modified: 2017-10-28 04:21:37, 4207 bytes

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