As you can see, screwdrivers antennas are big. This is a screwdriver antenna on VK2CD's modest Japanese car.
The VK2CD Screwdriver Antenna is designed and built by 77-year-old Maurice Jones, vk2cd, an Aussie amateur radio operator who has been hand-building antennas in his workshop since the 1970s.
Back then in the the days of the Australian CB craze (which is when I got into Amateur Radio myself) Maurice was winding helical CB antennas using a lathe to turn them as he slowly wound copper wire around and along the length of each unfinished fiberglass tube. The antenna would then have a tube of heat-shrink tubing applied to the outside. Heat would be applied to the outside to tighten the plastic, and the tip would be sealed with a small plastic cap. Voila!
His expertise was soon recognised by outlets such as Dick Smith, who was just one of the two-way radio outlets which ordered his helical CB whips. And then came mobile phone antennas (vehicle mounted cellphone antennas) and later Australian UHF CB antennas for 477 MHz.
Back in those good old days, Maurie told me he could earn $1000 a week churning out cb antennas for the stores. But that was another era.
Maurice showed me the adjustable coil from one of his vk2cd screwdriver antennas.
These days Maurice, (or Maurie as his friends call him), turns out hand-built HF screwdriver antennas from the workshop in his garage, at tha back of his modest house in Cardiff, New South Wales. It is a quiet little suburb that’s just south of the city of Newcastle, and around 150 Kilometers north of Sydney Australia.
When I visited Maurie yesterday, he told me he builds his VK2CD screwdriver antennas in batches of seven. He tests each one by bolting it to a steel plate he has screwed to the fence of his backyard swimming pool. And he did this for the one I bought from him. (Now I have to work out a way to mount and install it on my van.)
Then Maurice ran two cables from his workshop to the antenna and attaches two-conductor control cable for the electric motor and a BNC connector for the RG-58U coaxial cable. Maurice tells me that BNC connectors are much tougher and more waterproof than the more common PL-259 plugs or UHF connectors. And I know they are favored by the military for this exact same reason.
The cables run to a momentary toggle switch that sends 12 volts DC current to the antenna motor. Pushing the switch up moves the antenna‘s steel cover up, while pushing the switch down winds the steel tube down. When the screw mechanism reaches its limit, the screw threads have been machined off and the tube stops trying to move any further. The electric motor will still turn, however, so it is important to make sure nothing can press the switch accidentally, as this could burn out the motor.
While testing his antennas on the fence, Maurie marks the resonance points for the 40m amateur band with pencil on the dark gray, and for the maximum and minimum lengths of travel he leaves two white bands. This makes it easy to see from inside your car or truck if and when the antenna has screwed up to its maximum height, or back down to its minimum length.
The steel whip antennas he sells for the screwdriver have one extendible section. He says to keep the antenna pushed down to its minimum height of 3 feet while driving. This makes all bands between 80 meters (HF) and 6 meters (VHF) available to you. But when you want the 80 meter band, you will need to stop the car and extend the whip to its 5 ft 7 inch maximum height first. This is for the whip. The screwdriver coil adds about four feet again to the antenna’s height, depending on the way you mount it.
Maurice has given me permission to publish his screwdriver antenna plans here. His antenna has been through several minor changes and improvements over the years, so these are not completely up to date with what he is doing today. However they will allow any technically-minded person to build a useful and very functional HF screwdriver antenna. So I take my hat off to him for his generosity.
The email address that shows on this picture (below) is out of date. If you wish to contact Maurie directly, his correct email is vk2cd [at] qsl.net — and his phone numbers are 02 4023-4509, or 0414 569-996 from inside Australia. From overseas, you would need to dial 612 4023-4509 home, and 614 1456-9996 (for his cellphone/mobile phone). His screwdriver antenna costs $400 AUD, not including the adjustable stainless steel whip, and postage or shipping depends on where you live.
Screwdriver Antenna Plans
Screwdriver antenna plans for the vk2cd antenna, courtesy of Maurie Jones, its designer. (Click to see it full-size.)
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