Amateur Radio in Australia (VKFAQ)

Mobile Amateur radio operation on HF bands

ICOM IC-7000

The IC-7000 is a development of the IC706 MkIIg, with similar bands (HF and up to 70cm) and power (adjustable up to 100w on HF/6m, 50w on 2m, 20w on 70cm). The most noticeable difference is the colour screen which can also display TV signals. One mobile operator said the TV was so convincing he nearly left the car during an ad break...

Mobile operating

Amateurs planning long trips, or who have long commutes often install radio equipment in their vehicles. This has been made easier in recent years with the development of compact mobile transceivers that cover all commonly used HF/VHF and UHF amateur bands. Mobile VHF/UHF operation via repeaters is most popular. However international and interstate contacts are an everyday reality for the HF mobile operator. The secret tosuccess is antenna system efficiency - especially critical on the lower HF bands.

As well as operating from their own vehicles, Australian amateurs also operate from trains, trams and buses. Use is made of the 144, 432 and 1296 MHz bands for this purpose. Most contacts are via terrestrial repeaters, but communication has also been achieved via amateur satellites.  Here are some Hints on antennas and techniques.

On HF the standard mobile whip in the 70s and 80s was usually a centre loaded type, about 1.6 to 1.9 metres long, with a loading coil about half way up. The impedance of such whips is always quite low so there are serious impedance matching issues to overcome as well as the tuning of the loaded antenna to resonance. The location of the whip on a car body was also a significant factor.

Various manufacturers still make substantial looking whips such as the Texas Bug catcher and the more sleek whip series from Hustler, which have survived the test of time.

Helical whips are also popular whether home made or commercial versions such as those from Mark Helicals in the US, or Mobile One in Australia. The WA based Terlin company has been successful world wide with their Outbacker and other models, which are a tapped adjustable helical. These are used by outback HF users throughout Australia and the amateur version is a development of the commercial whip.


Next: Fox hunting, or radio direction finding

About VK1DA | Site Map | Privacy Policy | Contact Me | ©2008 Andrew Davis