SARC 24 GHz Beacon

A Lesson in Innovation

Call Sign: VE7SAR/B Location: CN89ne Band: 24 GHz Mode: CW Frequency: 24.192225 GHz Power: 70 mW

At the MUD 2024 (Microwave Update) conference in Vancouver, Dino VE7NX met Hugh VA3TO and Peter VA3ELE, two of Canada’s most active microwave hams. Both hold numerous band records and are frequent winners of microwave contests. They encouraged Dino to build a 24 GHz beacon, saying, “If you build it – they will come.”

Building the First 24 GHz Device in BC

With their support, Dino built a portable 24 GHz setup using a Wavelab system from Hugh and a 14-inch dish from Peter. This is believed to be the first 24 GHz terrestrial device in BC. Building at this frequency is no small feat—Dino had to acquire a 26 GHz spectrum analyzer just to proceed. With no available schematics for a 24 GHz beacon, improvisation was essential.

Local Oscillator Challenges

The first hurdle was the main Local Oscillator (L.O.). Paul W1GHZ had designed a PCB to triple L.O. frequency, but its MMIC chips were only rated up to 10 GHz. Unsure if it would work beyond 12 GHz, Dino built the multiplier PCB, set the L.O. to 4.032037 GHz, and tested it. After tuning the cavity filters, he successfully achieved a 12.096 GHz output. This now needed to be doubled.

Amplifying the Signal

Scott VA7SC provided a crucial doubler block/amplifier, bringing the output to 24 GHz. However, the power was only +3 dBm—insufficient for beacon use. Dino reached out to Barry VE4MA, a well-known figure in the global microwave community, who supplied a 100 mW 24 GHz power amplifier. After retuning and attenuation adjustments, Dino achieved a solid 70 mW output at 24 GHz.

Antenna and Beacon Installation

The beacon uses a 2x10 slot omnidirectional antenna purchased from Bert PE1RKI. Scott then fabricated the waveguide, handling the welding and weatherproofing. Together with John VA7XB, Scott and Dino installed the 24 GHz beacon above the existing 10 GHz beacon on the roof of the Concord Tower, home to SARC’s VHF/UHF repeaters. At John’s suggestion, they also added a 12V power distribution panel to support current and future beacons (the next planned is 47 GHz).

Testing the Beacon

After installation, it was time to test coverage. Dino successfully received VE7SAR/B from home using reflections, despite lacking direct line-of-sight. Scott confirmed reception across Langley, BC, and even from Cypress Mountain in North Vancouver. The CW beacon signal was clean and strong. Ray W7GLF—the only 24 GHz operator in Washington State—has been notified to listen for the beacon at his next opportunity.

A Team Effort

Building a beacon takes teamwork. Dino and Scott extend their thanks to everyone who contributed to making this project a success.

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