E51WL/B -50.049 MHz-Penrhyn Atoll-North Cook Islands
STATUS : January 2023 - presently on Warwick's 6m Yagi when he is not on 6m himself.
The keyer still needs reprogramming ... the actual locator is BI01XA (not BI00XX).
The beacon was built on a PC board base in "dead-bug" style with more PCB used to form compartments enclosed with tin plate tops. The PCB is fastened to a 4mm thick sheet of aluminium which is riveted to several strips of heatsink material. The beacon remains cool during continuous operation. No external fan cooling is required.
The RF stages are:
2N2222A Colpitts crystal oscillator operating at 8V
2N2222A Class-A buffer amplifier operating at 12V
40673 DG-FET high input impedance 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 24V
2N5643 Class-C output stage power amplifier operating at 24V and producing 40W RF power output
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 to switch 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 and to produce a distinctive sound.
. . . . . . . . . . DE E51WL/B BI00XX
The beacon transmitter draws just 2.1 amps from a 24 Volt supply and the CW keying reduces the average current drain to approximately 1/3rd of that.
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
Intermittently 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, 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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