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ANNOUNCEMENT  **********************************************************************************

****  November 2016 ****
The WM LowFer Beacon is on the air with a new Exciter and ID Format.   The U3S exciter has been swapped out and replaced with the QRPLabs Arduino Shield transmitter.  I have written a custom Arduino sketch to better support  LowFer Beacon needs, and it allows me to make ID format changes  very quickly.   Also for the 2016/2017 Beacon Season I have modified the Helix can in an attempt to improve the loading coil "Q" factor.   The Umbrella tophat on the antenna was swapped for the flattop that I used initially. A new webpage has been added detailing these changes. Click here to view that page;


The Wm Lowfer Beacon is a radio transmitter located in Southern Illinois near the Indiana border.   The analog version of the beacon was originally constructed and operated by Bill Ashlock SK. After his passing,   I volunteered in 2014 to put his station back on the air from my home.  It operates within the FCC Part 15 rules in the 160 to 190 Kilo Hertz band.  The station is designed to operate 24/7 sending a graphical identification looking like the letters Wm.   This identification can be viewed using computer software designed for viewing very slow morse code commonly called QRSS.   One example is shown in the following image.

Wm Beacon Capture

The radio station consists of three major components.   The first is the controller / exciter.  The purpose of this box is to create the graphical image that is transmitted, generate the radio signal to be transmitted over the air, and provide power and control signals to the Radio Frequency Power Amplifier component located at the antenna.

Master Controls

Inside View

Interior of Exciter

The Radio Frequency Power Amplifier component increases the weaker signal from the Exciter to the 1 watt level allowed by the FCC Rules.   The Radio Frequency Power Amplifier is located at the base of the Antenna in the Helix Box.   This location is chosen to allow the strongest signal to be sent over the air, while following the FCC rules for this type of station.   Either of these designs can be swapped into the Helix Can.  The Class E design can output more power than the push/pull, at a lower supply voltage.

Push/Pull PA using bi-polar transisters:  (Used for the 2014/2015 season)         Class E PA using a power MOSFET: (Put in service Fall 2015)
 place holder Class E PA

The Helix Can houses the Radio Frequency Power Amplifier, and the antenna coupler which connects the antenna to the power Amp.  This plastic trash container was just the right size to house the loading coils.  A smaller Litz wire coil slides up and down inside the larger coil to tune the antenna.   The swinging lid is sealed tight with silicon caulk.   I can remove the top and make adjustments while staying on-the-air.

Helix Can   Revised loading coil  inside view of the Helix

The final component of the station is the Antenna.   The Antenna will transform the electrical signals from the Power Amplifier into Electromagnetic waves which will travel around the country.


For the 2015-2016 LowFER season I am switching the exciter to a QRPLabs Ultimate 3S transmitter, along with a new antenna system in a different location on my property.  I will be able to switch either the analog or digital exciter inline, as both will use the same PA/tuning/Antenna system.  The image below shows the U3S being packaged inside a "Can of SPAM".  Also seen is a 8-25V to 5V dc converter, the BNC antenna connection, and the cable which feeds the GPS receiver.

new U3S Exciter 

The transmission format is a combination of FSKCW with a 30 second dit time, and a W/M graphic. A sample is shown here
that was used up to January 16, 2016. 

U3S Lowfer sample

The beacon was updated with new firmware on January 16,2016, which allowed additional flexibility to the graphics.   Also a suggestion was made to combine the separate FSK segments which might allow better recognition of the ID.  So the FSK was combined, and  "WM" portion was made to look more like the analog version.

wm lowfer version 2