In car CB vs hand held?

[Snaga Wishing I was lost Find all posts View Profile Close Snaga]

Look at Prestige Communications in Perth. Good starting point for what available.


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[Palmer Advanced Member Find all posts View Profile Close Palmer]

I started with handhelds, but soon learned about range problems so ended up taking advice from on here and got a decent GME in-car unit. This is SO much better and I can use my handheld for other uses now.

[Guest Close Guest]

This package doesn't look too bad
GME TX3100 + TX670 + 5dB antenna for $278
http://www.ebay.com.au/itm/GME-TX310...346968f&_uhb=1

I have the TX670 handheld and it is quite a small unit. I trawled the net for reviews on it and many complained about the low volume. However, they were pretty old and was probably for an old revision. I have had no issues with the volume in a busy shopping centre or walking outdoors in peak hour traffic.

[Vk3zgw Junior Member Find all posts View Profile Close Vk3zgw]

The thing to remember with any UHF system is that losses in your system will severely effect overall performance. More so than at other frequencies like VHF and HF. These losses include any voltage drop during transmission, long antenna coax runs, poor antenna location to name the obvious.

Most UHF rigs only provide the full 5 watts RF out at 13.5 volts, so don't run light cable to the radio. Use good quality coax cable for the antenna. RG58 50 ohm coax comes in many forms. Get one that has the full screen like RG 58U. RG58 is like any cable, it has losses. A 3 metre run of good quality RG58 has a loss of approximately 0.9db at UHF CB frequencies.

What does this mean. Well, with a 3db loss you will 1/2 the transmit power arriving at the antenna. That means a run of antenna cable approximately 9 metres and fed from a 5 watt transmitter will end up with only 2.5 watts input to the antenna. So keep your antenna cable as short as possible and use good stuff. Also, these losses affect the receiver sensitivity.

Antenna location is important too. Hand helds are notoriously bad for antenna matching. That is, the matching of the antenna itself to the power stage in the radio. This is because of the physical limitations of mounting an antenna on the radio itself where it is close to your hand/head during transmission. This effect capacitively de-tunes the antenna making it's match to the radio such that some of the power delivered to the antenna is reflected back to the power stage in the radio. This is known by the term VSWR or "swer" as its called. Not to say also, what having a RF level of this magnitude next to your brain does!

External antennas are definitely the go for best results. And not on the bull bar if you can avoid it. Going for a high gain whip on the bull bar to overcome the losses in mounting it in that position will not recover those losses. It also produces a very directional radiation pattern from the antenna.

The best place for any mobile antenna is in the centre of the roof with an unobstructed view of the world. But that's not always possible. So a compromise has to be made. My CB antenna (a ZCG GRN) will be mounted on my roof rails with the coax going through the door pillar to the radio (PRM 80 converted to UHF CB, and yes, I set it to 5W) located under the driver seat.

If you want range, ie performance from your UHF, these losses must be considered and managed as best you can. As an experiment get hold of a UHF power meter if you can, first connect it at the radio's antenna socket and read the transmit power out of the radio itself. Then reconnect the antenna cable at the radio and remove the antenna whip which should be screwed into the same type of SO239 socket at your antenna base that is on your radio. Connect the power meter to the end of the coax then measure the power when you transmit. If you are loosing more than 1 watt your performance is suffering.

If you don't have the gear to do this test, hook up with a local ham, they will usually be happy to help out.

Cheers
Geoff

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External antennas are definitely the go for best results. And not on the bull bar if you can avoid it. Going for a high gain whip on the bull bar to overcome the losses in mounting it in that position will not recover those losses. It also produces a very directional radiation pattern from the antenna.

The best place for any mobile antenna is in the centre of the roof with an unobstructed view of the world. But that's not always possible. So a compromise has to be made. My CB antenna (a ZCG GRN) will be mounted on my roof rails with the coax going through the door pillar to the radio (PRM 80 converted to UHF CB, and yes, I set it to 5W) located under the driver seat.

This is my way of getting the antenna up high but still being able to get into low clearance car parks.
http://www.pradopoint.com/showthread...ckdown-feature

I've noticed that my low gain rubber duckie antenna up on the roof is performing about the same as the high gain whip antenna on the bullbar.

[Vk3zgw Junior Member Find all posts View Profile Close Vk3zgw]

I would imagine there would be some directivity difference between the 2 locations amts.

Geoff

[Guest Close Guest]

I would imagine there would be some directivity difference between the 2 locations amts.

Geoff

As in when the antenna is vertical and horizontal?
The antenna will only be in the horizontal position when not in active use.

I was in convoy once when coming out of an underground carpark and there was no place to put the antenna back up vertically. I was surprised that I could still communicate with the other cars who had handhelds going down the freeway. I think we were probably 300m apart from myself to the last car - 3 car convoy.

Edit: or do you mean roof vs bullbar locations?

[Vk3zgw Junior Member Find all posts View Profile Close Vk3zgw]

Sorry, I meant between the bullbar antenna and the roof one.

[Guest Close Guest]

Sorry, I meant between the bullbar antenna and the roof one.

Yes, that's right.

And with people breaking antennas travelling over corrugations when mounted on bullbars, perhaps they are better off mounting them on the roof and not needing such a high gain antenna to compensate (as per your previous posts).

[brogers Advanced Member Find all posts View Profile Close brogers]

Both....an in-car radio...AND...also two small hand helds two ways as well ...IMO

Its so easy to talk to someone outside the car during a recovery if you give them a small hand held.. or with another car who doesn't have an in-car radio, you can loan them one of your small hand held radios...they are great. I keep two little cheap Oricom hand held radios in the car all the time, and we used them a lot on some recent trips...both off road, on the highway, in the desert AND on the water...ie when fishing with some other boats...we gave a mate one of the hand helds for his boat and we took the other...it makes life so easy. anyway....and when the car antenna broke off in the desert, we used the small hand held one all the time...it was a great back up when crosssing the dunes, would have been tricky without the small hand held radio after the car radio became useless without an antenna...so just as a back up it was worth a hand held (or two) as well ..anyway, thats just a a couple of other things to think about ..

[MidLifeCrisis Out of control poster! Find all posts View Profile Close MidLifeCrisis]

I have an ICOM unit in the car (model with controls on the Mic, and a 5W hand held uniden. We went with the 5W Uniden as its waterproof and allows travel away from the base camp by teenagers (or wife) to a decent distance. If you have older kids, or bush walk on trips, then go a decent waterproof unit. An in car charger is also a must on longer trips.

There have been trips when newer members have used my hand held as a car based unit without any problems.

[BiLLz0r Advanced Member Find all posts View Profile Close BiLLz0r]

I thought I'd post a follow up to my own thread. I've decided on a GME TX3100 Plug'N'Play.
It means I can take it out when not in use and loan it to my dad when he goes 4WD'ing (or even use it in my daily driver if I like). The TX3100 gets great reviews being a basic 5W unit. I also Googled the antenna model I have today thinking I can remount it and plug the more powerful antenna in if need be. Turns out it's a 6.5DBi Mobile phone antenna and was attached to the iphone car kit in the car. I guess they did some touring in it before we bought it.
Now to find the cheapest place to buy it. Ebay @ $252 seems good so far.

[r4ndll Avid PP Poster! Find all posts View Profile Close r4ndll]

I've got the 3100 permanently mounted, but I very nearly got the plug and play. It's a nice basic unit and I've never had any trouble at all.

I also picked up a couple of 1W handhelds from Aldi for $30. Limited range and v basic, but I don't care if they get lost or damaged. I mainly use them for the kids to talk to the other kids in convoy on an alternate channel or keeping tabs on them round the caravan park. They are handy to lend out if required as well.

I'll get some better units at some point.

[gantulga Junior Member Find all posts View Profile Close gantulga]

CBs are vastly superior than the hand held two-ways. they are only good when you are out "peeping" and suddenly you sense a wolfpack stalking you hehe". CB's will make difference if the unit has long range antenna. and again, cheap hand held radio are "handy" but you will need to swap batteries or charge them during trip also the use of the handheld radio when driving is not pleasant.

[BiLLz0r Advanced Member Find all posts View Profile Close BiLLz0r]

Well I bit the bullet today since Rays Outdoors had 20% off. $239.20 for a GME 3100TX PnP. Installed and working great. Cheaper than Ebay and anywhere else.