Batteries, Radios and Fridges- Part 2

Saturday, Jul 03, 2021 at 09:22

Olsen's Tours and Training

In Part 1 we examined fridges- do you need one, how to ensure it runs well by having heavy enough wiring and much more. we then added an extra blog entry of an example tour without a fridge, and what you may have to consider. Now let's move on to radios and then in the next blog, batteries.

I've been using and installing radios in cars since the mid 1970's, starting with the 27MHz CB's that were so popular in that era. I gained my Certificate in Radio Telephony for ships, a year before it could be issued to me due to my age. I now hold a Advanced AOCP (Amateur Operator's Certificate of Proficiency). I've been using HF radios since I was 14- that's many decades.

Let's start however, with UHF radios typically used for car to car communications in a convoy situation such as a 4WD tour group, whether that be a commercial operation or just a bunch of friends on tour.

Hand-held UHF radios: Hand-held UHF radios are very useful devices, for towing operations, recovery and many other situations. Some of my tour participants who have travelled with me for many years, carry them on their person because many of the women leave camp on foot every morning, as a group, to walk ahead of the convoy before it departs. I usually advise them of any potential navigational errors they could make as they walk, and they'll use the radios to call back should they get confused. They can't walk terribly far, so the range of the hand-held is usually sufficient for this purpose. They enjoy a fantastic morning walk, typically in the desert regions where the wildlife is more active at that time of day.

Some tour participants resist fitting mobile UHF radios and antennas to their vehicles and ask me if they can use a hand-held radio. The answer is, yes, of course you can use a hand-held radio, but you may well miss much of the conversation.

While convoy management procedures ensure you won't get lost or detached from the group, even without a radio, there is much that you will miss, particularly on the better gravel roads where convoys can stretch out to many tens of kilometres. You also may not be heard, even with 5 watts of transmit power, due to the smaller inefficient antenna.

UHF mobile radios are quite inexpensive, especially compared to the amount you will spend on fuel, so I recommend buying and fitting one. If you are even half-handy, you can fit it yourself or ask a handy friend to do so.

Antennas. You may be tempted to save a few dollars on the antenna. I recommend you do not. The antenna and feed-line (coaxial cable) are perhaps the most important parts of the radio setup. Not only does a better quality antenna give you more range, they last longer. If you wonder why all of the tour operators have beefy broomstick style antennas and not wimpy stainless steel ones, it's because the stainless steel ones cannot handle vibrations of even mildly corrugated roads. I'd like a dollar for every stainless steel whip antenna that broke on the first day.
If you have one, here is a trick we use to prevent them breaking.- find some clear tubing (commonly referred to as beverage tubing) that fits snuggly over your antenna. You will need a piece about 75% of the antenna length. Slide it over the antenna. This stops the sinusoidal waves forming that work harden the antenna at the nodes. This stops the antenna from breaking on even the worst roads.

So what about antenna length and gain. Well for most purposes you want an antenna of moderate gain which typically means not too long. It is more important that it is a manageable length that won't get caught in the trees on tracks like those on Cape York, The Hay river, The Kimberley etc. Just get a good beefy broomstick of a length that is manageable.

Powering the radio. Do not be tempted to use a cigarette lighter socket. Connect you radio to the battery via a fuse on each leg. Ensure the fuses are close to the battery.

Feed-line. Ensure the feed-line is not in a position where it can get squashed. Coaxial cable relies on the diameter of the materials in the coaxial cable to deliver the correct impedance. Do not squash it. if you buy new cable, buy good quality double shielded 50 ohm cable.

We'll talk about HF radios in another blog.


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