A 40W 6m beacon custom built to run on Warwick's existing 28 volt solar power system.
Current status (since Dec 2012): Operational.
The beacon was built on a plain PC board material base in "dead-bug" style with more PCB used to form compartments that are enclosed with tin plate caps. The base is fastened to a 4mm thick sheet of aluminium plate which is in turn riveted to several strips of heatsink material. The heatsinking is "a complete over-kill" and the beacon does not get even slightly warm even after several hours of operation. No external fan cooling is required.
The RF stages line up is:
2N2222A Colpitts oscillator operating at 8V
2N2222A Class-A buffer amplifier operating at 12V
40673 DG-FET high input impedance buffer and keying stage operating at 12V
2N3553 Class-A pre-driver amplifier with the base bias also keyed, operating at 22V
BLY93A Class-C driver amplifier operating at 28V
2N5643 Class-C output stage power amplifier operating at 28V
All "old school" stuff for ease of maintenance in case of failure - Penrhyn Atoll is a VERY remote place!
The Morse Code ident is generated by an ID-O-Matic board from HamGadgets driving a 2N2907A PNP transistor switch to the keyed stages.
The keying sequence consists of a string of 10 "dits" followed by the callsign and grid locator in a 26 second cycle. The string of "dits" (rather than a continuous carrier) was deliberately chosen to reduce the average current consumption from the solar charged battery power supply. The beacon transmitter draws just 2.1 amps from a 27 Volt supply and the CW keying reduces the long term average current drain to approximately 1/3rd of that.
. . . . . . . . . . de E51WL/b BI00XX
Spurious emissions on the RF output are reduced by a low pass filter and a 1/4 WL shorted stub connected at the beacon's output socket via a T-connector. The shorted stub substantially reduces 2nd harmonic radiation and provides an element of lightning protection.
Many thanks to the following who have generously contributed to this project:
Mark ZL2WHO - for the first prototype, the source of many ideas for the MkII version
Steve ZL1TPH - supplying the HamGadgets ID-O-Matic Keyer
Kevin ZL1UJG - advice and assistance with the crystal order from Europe
Tim VK4TIM - supplying a Tait T182c RT as a parts donor for the MkII version
Warwick E51WL - site and antenna
Beacon history:
Solar panel arrived in Penrhyn - Feb 2011
Beacon arrived in Penrhyn - March 2011
Intermittantly under test on the 6m Yagi at E51WL QTH - April 2011
Some spots in South America - April 2011
Antenna built, an old CC R7 converted to a 5/8 ground plane - July 2011
Beacon installed on the solar powered supply, antenna at 15m ASL - August 2011
Heard in ZL - August 2011
The completed beacon under going a bench test.
Great Circle Map centered on Penrhyn Atoll, North Cook Islands.
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