A fair while back I said I was going to write up some "how-to" type posts for those asking about radio related matters - as it turned out I never got around to doing so. Thus I have decided to kickstart it tonight.

Before I start please note none of this is meant nor intended to be the 'be all and end all' of radio. I am happy to answer specific questions if anyone has them. Like most things everyone has their own version of what's right and wrong when it comes to radio and I'm sure there will be someone disagree with something I write here, but I'm not going to tell you something will save your a*&# when it won't.

At the end of the day any radio regdless of make or band is only as good as the person you are in communication with. If that person doesn't relay the information to the relevant party for you, or relays inaccurate information then your screwed no mater how good the radio system you have. Keep in mind you are relying on complete strangers for the most part to assist you (excluding HF networks).

First up, since they are the most common variant of radio we will discuss the various types of CB radio transceivers. Due to the decline in 27MHz CB production we can cover this relatively quickly. These days unless you wish to spend considerable money its almost impossible to purchase a new SSB 27MHz CB in Australia.

27MHz CB:
There are two variants; AM only and SSB (which has AM as well). As I said before buying a new SSB CB these days is harder then pulling a tooth from an angry tiger, although we will have a look at their benefits.

Pro's & Con's:
AM CB

• Cheap to purchase new.
• Good for hort range communication.
• Easy to install and operate.
• Can suffer from externally generated noise such as motors, electrical tools and power lines.

SSB CB

• Virtually impossible to purchase new in Australia.
• Good for extended/long rand communication.
• Easy to install, clarifying on SSB may take some getting used to.
• Can suffer from externally generated noise such as motors, electrical tools and power lines.

One big advantage with 27MHz CB over UHF (477MHz) is that they tend to perform better in forrested areas. So if one party is out walking with a hand-held and the other is at base camp communications (for the most part AM) will be pretty reliable. Although as a source of communication to the outside world in times of trouble 27MHz probably isn't in your best interests. The CB craze has long gone and the 27MHz band is pretty quiet these days - on the upside you virtually have it to yourself so to speak.

UHF CB:
UHF CB has gotten somewhat complicated in the last few months with the ACMA's marvellous conception of extending it from 40 channels to 80 channels. What was 40 channels spaced 25KHz apart is now all 12.5K spaced. This means any existing repeaters need to be upgraded to the new 12.5K spacing allocation; which will mean some repeaters dissapearing as it will be to much of a financial burden on the repeater owners to upgrade to new equipment.

There is even some oddness with the radios hitting the market, some are 80 channels, some 74 - I'm not sure what the 74 channel bit is about but they are out there on the shelves as I type.

Suffice to say 40 channel UHF CB's are going to be around for a long time to come yet. I can't see to many people rushing out to purchase a new unit, I definately won't be! And your existing 40 channel unit will work just fine, except that you will be minus the additional 40 channels on the new radios.

Just about every cat, dog and goat has UHF these days, and even in the country if you cannot find anyone on the 'truckies' (Channel 40) channel, if you put out a cry for help on every channel your bound to come across a farmer down the road or someone.

The average range (non-repeater) simplex is around 5-10K's this will depend largely on the terrain your in. In flat open areas you will experience greater ranges then this mobile to mobile. Repeaters can extend your range considerably although you have to keep in mind there are others also wishing to use the repeaters and if you hog it all day long you won't be the most popular users. Also if the other mobile you're talking to goes out of range of the repeater or cannot access it your stuck. So for group comms your best to stick to a standard channel and stay there.

Now there is a multitude of channels so-called designated for nomads, caravanners etc. In my mind its a bloody mess - pass a camper and try and call them, which channel are they on? Channel 40, 10, 20 - you get the picture.

To give you an example:
Channel 10 - 4WD's, convoy, clubs and national parks.
Channel 18 - Caravans and Campers.
Channel 29 - Apparrently the Pacific Highway replacement of Channel 40, why???
Channel 40 - Road channel.

I don't know who comes up with these hairbrained allocations but they must be on some damn good drugs. 10 is used commonly by 4WD's although I'm not so sure of the National Parks bit. When I am mobile I have my radio set to channel 40 and it also scans channel 5 (emergency channel) and channel 18. With the exception of where I am in a park which has logging trucks running then I will be on whatever channel is sign posted, for example Mt St Leonard uses Channel 19 for the loggers.

Antennas - Bigger is better... Not always:
Common myth with UHF CB is that you have to use one of the bullwhip/broomstick antennas to do any good. Not so. A simple 4.5db antenna mounted correctly will serve you well. It really depends on the terrain your going to.

If your travelling mostly on flat terrain then a high gain antenna is a good investment, if your in mountain areas you may find a simple quarter wave (with no gain) gives you better performance (especially when using repeaters) due to its higher angle of radiation. In a nutshell the higher the gain of the antenna the lower (flatter) the angle of radiation and vice-versa the lower the gain the higher the angle or radiation. There are some antennas that have two sections which can be either 6db or 9db. Also the bigger the antenna the more likely it is to bash against low hanging tree limbs. The type of antenna will largely be impacted by the type of vehicle you have. Most motorhomes don't allow for roof mounting (as they are commonly fibreglass).

Alright I think that's enough for now, maybe some questions will give me some direction on where to head next... over n out.. kerchunk.

VK3FEMT wrote:

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Antennas - Bigger is better... Not always:
Common myth with UHF CB is that you have to use one of the bullwhip/broomstick antennas to do any good. Not so. A simple 4.5db antenna mounted correctly will serve you well. It really depends on the terrain your going to.

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 In general I agree with this but keep in mind the need for a physically robust antenna if spending any time off the "blacktop".  It's been my experience on 4WD tag alongs that "broomstick" (as you neatly describe them) antennas that are supplied with a robust spring base are needed to withstand the punishment they get from corrugated roads and hitting obstuctions such as overhanging branches.

UHF CB is almost universally used for vehicle to vehicle communications and should be the primary choice for cravanners and RVers.

Dame Markalot, GME is a well known brand and they make a good reliable product. The TX3220 is a safe choice for your needs.  Buy from a specialist two-radio supplier rather than a toy shop such as Dick Smith etc.  They should be able to advise you the best option for the antenna.  Unless you have some technical background I'd suggest you have them install it for you.

By the way....

If monitoring Ch 40 (truckies channel) be prepared to hear frequent references, using good ol'fashion Anglo Saxon language, to human procreation and certain parts of the female anatomy!

Hi Stew,

Thanks for starting this thread and also to Jim for his feedback. Stew, this is a subject that some of us know very little about but would like to know about (and also feedback from others viewing it). How about contacting Cindy and asking her to make it a sticky on Tech's corner so it stays at the top, especially if you are going to add to it now and again.

Any thoughts on this suggestion Stew?  Well worth making a sticky out of it if Cindy agrees.....

Ok to answer Sharon's question I'm with Jim GME are a reliable and well known brand and have been around for years. If you're strapped for cash you could look at the Oricom UHF's, although I have no experience with them so can't comment on quality - best to spend the extra few bucks and go with the GME.

What town/city are you in (private message me don't post it here) and I can locate a good place for you to buy from and get an install done or at least the shop will be able to send you in the right direction.

As for antennas..
With the Navara, I would suggest going into either DSE or Jaycar and getting a Z Mount bracket. You simply attach this to one of the bolts under your bonnet on the quarter panel and it pokes out and you attach your antenna to that, saves drilling holes. I've yet to seen a 4.5cb (centre loaded) antenna snap when off-road, not saying it isn't possible I just haven't seen it myself.

Let's get a little technical here:
Say you have your GME (5 Watts output power) and a 4.5db antenna, at 5 Watts 4.5db antenna will give you an ERP (Effective Radiated Power) of a shake over 14 Watts. Moving up the scale to the 'broomstick' style antennas for 6db you will get an ERP of 19 Watts, for a 9db variant you will acheive 39.7 Watts (this is theoretical).

Remembering again, the higher the gain of the antenna the flatter the angle of radiation. Basically you need to think about what your going to use the radio for;

1. Is it just to talk to others in convoy or the truckies?
2. Are you only interested in using repeaters?
3. For use only in emergencies?

Some thoughts:

1. If your just talking to others in convoy or the truckies then you don't really need a big thumping antenna or anything with massive gain. You're spending your good money needlessly. I know a lot like the idea of having this massive antenna swinging around off their bullbars, especially the 4WD'ers I would suggest either a 4.5db stainless with an elevated feed (if your close handy to me I can give you one, I've got stacks!), this way you will have effective communications without hearing all the jibberish further afield that's not relevant.

2. If your using repeaters only, again 4.5db or a 1/4 wave is going to suffice for the job.

3. For emergency use only, then probably the bullwhip. Although these really need to be mounted on a solid surface and the Z Mount I mentioned earlier won't cut it for very long before it snaps in two.

Some antenna manufacturers use dbi for gain reference, which means decibels relative to an isotropic radiator - in laymans terms the perfect radiator, it doesn't exist in the real world. In reality an isotropic radiator cannot exist. So its just another confusing term used, but dbi figures can be converted to dbd or db for a more relevant gain calculation.

I wouldn't rely on UHF CB as a life-saving device, lets not get any illusions here. If you're in the boondocks the UHF CB may or may not be you're saving grace. Being prepared and having ample supplies is much more sensible then having a UHF CB. UHF CB is great for group comms, nattering and talking to other road users etc, although if you are going to venture into very remote areas the one thing I would 100% recommend buying is an EPIRB, they are not cheap - but then how much is your life worth to you? A good (GME) model with GPS capability will set you back around 500-600 dollars, you need to register it with AMSA/RCC. With the GPS version it sends your coordinates along with the distress beacon, thus allowing them to narrow down the search grid significantly. A non GPS version transmits two simultaneous signals, one for the satellites and another on 121.5 (Internation aircraft distress frequency) as a homing signal so the planes flying around looking for you can get a fix on your location and triangulate where you are to send in ground crews. With the GPS version they have your coordinates so the grid is significantly reduced meaning faster SAR time. Make sure if your buying one of these you get one designed for land use and NOT marine, marine ones are activated by being immersed in water, so if you drop it in water it will start beaconing. The land versions are manually activated by yourself. And the GME units also have a little strobe light built in, just another handy feature.

If you are going to use an EPIRB & want to use it in a marine aplication as well as land, buy a marine one as it is the only legal type to use in a boat. I required one for dual aplication & purchased a GME marine EPIRB & its registered with Canberra as marine & land use, they are quite happy about this. It is manually switched on to activate it. Having been involved with marine secues involving non GPS EPIRBS the response times with the satalite & fix is quite reasonable. The bigest time factor is geting rescuers to you. The time factor for getting a crew for a rescue boat or chopper & travell is where the big wait is.

Excellent post Stew.....

Thanks

A little more on the antenna... I have both a "broomstick" (probably 6db) and a lighter 4.5db, both bull bar mounts. I only have one of them fitted at any one time. (and neither when I'm not out on the road travelling). As I'm not venturing off road very much now I rarely fit the "broomstick" and find the 4.5 db quite satisfactory.

Also I have found those hood or trunk (boot) mount brackets to be not robust enough for off road use, however in the absence of a bullbar it may the most practical solution. (I have had one of these brackets show signs of fatigue to the point where a failure was imminent had I not found it in time, this was on a seriously corrugated road.)

(A bit of techie stuff.... keep in mind you need to increase the power by four times to double the signal strength)

PS: I have found that it's best not to monitor the repeater channels when in the city unless you want to have your intelligence seriously insulted.

Hi Chris,

If considering a handheld don't buy a "toy", get one from a known manufacturer such as GME, Icom, etc. Also if your existing antenna arrangement is generally satisfactory for your needs I see little point in "upgrading". If you're having a problem you could try a 4.5 db whip antenna roof mounted on a magnetic base but not too close to the signage.  Also take care not to pinch the co-ax from the antenna where you pass it through the door jamb.

Jim

Calling VK3FEMT can you here me, or I am flapping my gums at you Vk3FEMT, copy there.

I loved the Old AM CB, so I could not talk for miles at the time we were in miles but along comes this decimal thing followed by fm radio with this new form of usege, not very colour full language, over forty years of transport still can not wear it. It's totally crape.

Now as my memory tells me the reason for the 29 on the Pacific Highway was because if you were going along the say the Cybucca Flats north of Kempsy and asked for a road report you more then likely receive back a report of one for the New England which dare say used to get pretty interesting.

EG. "Hey drive whats it like in front?" answer "all clear drive, have ago" the response come back clear as a bell and that is why we have 2 channels because of the 2 highways getting crossed messages clear as a bell particularly in the night and that my folks is what happen to me, lucky that I don't trust everything I hear as  there was a vehicle coming in the opposite direction. I did not have anything to do with the change but suspect it was the regular overnighters that relied on the CB for there safe passage up or down the our Highways.

I do remember the cross over time when we had both am and fm in the trucks that was a real nightmare trying to keep up with both sets and at most confusing.

What always confuses me is why the people with the loudest and clearest sets need to use the language in the first place. Good grief don't get me started. Cheers   

beiffe wrote:

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I travel with Ch40 and talk to trucks behind me to advise I have seen them and for them to advise when they wish to pass.
Also I can tell when a wide load is coming or there is something ahead but I don't Chat like some you hear talking for something to do and blocking the truck drivers. Ch 40 is for work if you want to talk BS find another channel and don't use 1 -9 or 30 -39 as they are repeater channels used for important tasks.
I considered sat phone whilst working out bush for 3 months but decided against it. I travel on my own and advise no one where I am going as that is my wish (my plan is to not plan) but some like to keep family etc informed and in these cases a sat phone may be of use.
Regards
Brian

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 Except for channel 5/35 which is for emergency use only, the repeater channels can be used for general use. Although, in any populated areas, they are usually clogged by low intellect morons trying to outswear each other, and are pretty useless to anyone else.

Radar wrote:

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Calling VK3FEMT can you here me, or I am flapping my gums at you Vk3FEMT, copy there.

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 If you click on his nickname (LHS) you will see - Last Access         00:38 Jul 25, 2011

this topic is very old so you may not get any reply from VK3FEMT

Topic date July 10 2011

PeterD wrote:

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Wombat, if you look at the message before yours you will see that he has not been around since the middle of 2011.

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 Yes Peter I did see your post, I just wanted to point out that the topic was old and maybe the info was out of date.