There is a problem. We have a couple of GME 40 channel hand helds & an 80 Channel unit in the car. The 40's won't come away with us again. The problem is that whilst they work together with the now more common 80's , they don't work very well. I can't remember which way round it is, but transmission & receiving on one is perfect - loud & clear, whereas the other transmits ok but the volume is barely audible even when turned up full. Not loud enough to hear over normal car noise. It may be worse with some brands/models than others but it is a documented problem between the old 40's & newer 80's & it's likely if you need to use it you will be talking to someone who has an 80. No problem with 40 to 40.

Even if you test yours ok with an 80, there is no guarantee that it will work with a different 80 when you need it.

We don't use our car unit that often, but when it's been needed it's been exceptionally useful. I wouldn't want to be without it, but we do a fair amount of off road stuff. For a once in a blue moon scenario like you described it'd be worth replacing your one with a new 80 I reckon.

If you can, when checking out a new one, try to listen to it first. Sound quality is very variable, more so among cheaper models, but not restricted to only the cheaper models. I put up with a cheap Uniden dash mounted one for a while until it thankfully died on me & I replaced it with a better quality item (Icom). The difference is that I could actually understand what was being said to me, whereas with the cheapie it had always been a struggle. A straight swap over using the same cabling & antenna proved the problem was with the UHF unit itself.

 

-- Edited by Cuppa on Friday 21st of April 2023 12:45:06 PM

Craig1 wrote:

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You still have the main channels, but no access to the new 40

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Yes he does, sort of :)

It is certainly worth taking your UHF CB with you if for no other reason than to talk with trucks who may wish to overtake you.

To explain the channels thing:

When UHF CB was first permitted in Oz each of the 40 allocated channels was given a "width" of 25kHz. As time passed and the 40 channels became crowded the ACMA decided we needed 80 channels but they did not want to allocate more RF space so they reduced channel width from 25kHz to 12.5kHz and, thus, instantly created 80 channels - new radios were designed to work with the 80 channels but old radios just carried on in their merry way. The consequence being that if you are listening to, say, channel 28 on your old 40 channel set you are actually listening to 28 and 68 on the new 80 channel system and likewise if you transmit on 28 you're transmitting on 28 and 68. In this situation the guy listening on an 80 channel set may find the audio distorted and the guy listening on a 40 channel set may find the audio low in volume but both should be able to communicate adequately.

The ACMA originally intended to phase out 40 channel sets but as all seemed to be working in harmony they decided not to but do be aware when using a 40 channel set that that you may be clobbering somebody on another channel so, if asked, have the courtesy to move.

Just went down the road and bought a 80ch (thanks to you guys) at super cheap $200 Oricom UHF5400 with optional speaker mic. the problem is I can sort of work it, there is no squelsh knob like my old 40ch and words like scrambler, vox, tri watch on, roger beep on, ctcss on, dcs on, apart from that I sort of know. 

RickJ wrote:

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Bulldozer wrote:

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Just went down the road and bought a 80ch (thanks to you guys) at super cheap $200 Oricom UHF5400 with optional speaker mic. the problem is I can sort of work it, there is no squelsh knob like my old 40ch and words like scrambler, vox, tri watch on, roger beep on, ctcss on, dcs on, apart from that I sort of know. 

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 Bit of a shame you bought another radio on forum heresay. 

I phoned an ex member and owner of a fleet of trucks and for normal communication your 40 channel unit was fine.

Trucks use UHF 40 and UHF 29

See the attached for more information.

 

https://www.truckfriendly.com.au/wp-content/uploads/2021/04/uhf-radio-use.pdf

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 I'Ve AN idea that your information would have came from Rob, and agree that what you have been told is correct.

It is (or should be!) common practice for caravanners to predominately use channel 18 to discuss the next tea-and-bikkies stop instead of boring we truckies with their idle chatter.  Cheers

 

-- Edited by yobarr on Friday 21st of April 2023 05:05:45 PM

Bulldozer wrote:

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Channel 18, now I know, tea and biscuits, No heresy with me Rickj,  i'd pretty much made up my mind before I posted here. After 16 years I think I deserve a new UHF 80ch 

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 As long as you are happy Bulldozer, either radio will do the job.

Guessing information for the sake of a post can be quite detrimental when that information is not quite correct and can cause various degrees of inconvenience to others.

 

@Yobarr,

Yes, when I read this topic I was in extreme doubt as I actually have a 40 channel GME UHF set in my own car.

When I bought it, the company that fitted it told me that there was an option of the 80 channel but they suggested that if I wasnt involved in a club which might want to use permitted channels above 40 then the 40 will continue to work fine for highway travel. My radio works fine on CH 40.

This at the time was verbal but a quick call to Rob verified it and he gave me that link above as well.

BTW he sends his regards to his old sparring partner..  

RickJ wrote:

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Bulldozer wrote:

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Just went down the road and bought a 80ch (thanks to you guys) at super cheap $200 Oricom UHF5400 with optional speaker mic. the problem is I can sort of work it, there is no squelsh knob like my old 40ch and words like scrambler, vox, tri watch on, roger beep on, ctcss on, dcs on, apart from that I sort of know. 

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 Bit of a shame you bought another radio on forum heresay. 

I phoned an ex member and owner of a fleet of trucks and for normal communication your 40 channel unit was fine.

Trucks use UHF 40 and UHF 29

See the attached for more information.

 

https://www.truckfriendly.com.au/wp-content/uploads/2021/04/uhf-radio-use.pdf

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 'Not forum hearsay'  Your ex member friend might want to google 'low volume on 40 channel UHF when communicating with 80 channel UHF'  to bring himself up to date, unless you have mistaken 'Channel 40' for '40 channel.'  The link supplied says nothing about communicating between the two types of UHF.    

In the interest of fact Rob has sent me the following information.

Lets just get this into perspective.

Trucks do not operate on Channel 80 unless for a private conversation with another who has Channel 80.
The road or highway Channel is commonly 40 and the main exception being Ch 29.
Please refer to the attachment in the link above.

Varying volumes and differing performances when comparing UHF radios is not because of the amount of channels but more to do with design and brand of handheld or mounted unit. The performance is dependant on location of transmitter and receiver surrounding terrain and more so than anything else the SWR tuning of each unit.
Handhelds have built in antennae and may or may not be tuned to the optimal SWR.
Many truck operators have SWR meters and knowledge to fine tune their radios.

https://www.rightchannelradios.com/blogs/installation-guides/18428275-understanding-swr

https://www.rightchannelradios.com/blogs/installation-guides/18330687-cb-antenna-tuning-instructions

Tuning The Antenna
Set your transceiver to the lowest operating frequency or Channel 1. Remove TIP from top of the antenna remembering that the TIP makes a difference as it lowers the frequency slightly, so remember to replace the tip when measuring SWR. Use a razor blade, knife or side cutter (don't crush the fiberglass, cut it!) Carefully cut 3mm off the top, then replace tip, then measure SWR reading on Ch 1 and Ch 40, The SWR will improve on Ch1 quicker than on Ch 40. Continue to cut the antenna, as the antenna lowers in SWR, you may need to cut as much as 30mm.
You need to achieve a SWR of better than 1.5:1 on Ch 1 to Ch 40 with the best reading on Ch 20 (you decide)
CAUTION: As SWR reaches it's lowest point, cut only small amounts of wire off antennas to avoid over trimming.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

-- Edited by Webmaster on Friday 21st of April 2023 09:25:46 PM

RickJ wrote:

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Varying volumes and differing performances when comparing UHF radios is not because of the amount of channels but more to do with design and brand of handheld or mounted unit. 

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In regard to audio volume that is not correct.

UHF 40 channel CBs with 25kHz channel spacing have greater FM deviation than 80 channel units with 12.5kHz channel spacing, thus an 80 channel unit receiving a 40 channel unit may be overloaded in its audio stages and a 40 channel unit receiving àn 80 channel unit will produce a lower volume than were it receiving another 40 channel unit.

Mike Harding wrote:

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RickJ wrote:

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Varying volumes and differing performances when comparing UHF radios is not because of the amount of channels but more to do with design and brand of handheld or mounted unit. 

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In regard to audio volume that is not correct.

UHF 40 channel CBs with 25kHz channel spacing have greater FM deviation than 80 channel units with 12.5kHz channel spacing, thus an 80 channel unit receiving a 40 channel unit may be overloaded in its audio stages and a 40 channel unit receiving àn 80 channel unit will produce a lower volume than were it receiving another 40 channel unit.

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 Thank you Mike,

I am not over familiar with the two radios operating systems but I do know that the channels are closer on the 80 channel.

I sought the knowledge of Rob Driver who I know understands all of this.

Maybe he might want to go into more detail, but on reflection maybe not.

It is good to have members like you still here that do know what they are talking about.

 

Your post has missed the point again plus provided irelevant information on the issue under discussion. Mike Harding is correct. Try googling as suggested. It's a well documented issue.

It wasnt me or anyone else that told the OP he needed an 80 channel UHF when he had radio set that would do what he wanted.

As the OP said he was wanting to buy a new unit so ,so be it.

 

so I would expect all truckers & most other UHF users would be on 80ch now.

Using a 40 channel UHF while talking to an 80 channel radio on the same channel number may or may not work, depending on quality and make of radios, antennas used, terrain, quality of microphones, speakers and tone of the voice and mic technique.

There may be interference from the adjacent channels due to overlap. There could even be an internal fault in a radio that drags the performance down.

The reason given for the late non-change was that despite the long notice period and publicity, a vast percentage of the thousands of truckers had not identified the need for change. No-one had approached the transport industry advising of the change. So they had not picked up on it.

The bit re antenna tuning applies to the old HF CB scene - 18 and 40 channel versions.
UHF antennas are precisely cut ready for use ex factory, no tweaking required. One might play, but be prepared to only trim less than a mm. There is a fequency difference of almost 20:1, so tuning snips on a straight antenna would only be 1/20 of what was a normal snip. On the compound types with the inbuilt coils and the ground-independant types you could well be really mucking things up. Much better to leave alone.

As much as you can, make sure that the antenna is right for your needs - gain versus radiation pattern ( near field work - distance) and that it is not hampered by nearby metalwork/other antennas.

i had one in my previous car but sold the radio after the wife passed away........ we only used it mostly when reversing into a spot .......now i do it all on my lonesome by in and out of the vehicle to see how im doing......

Hi everyone,
In relation to the first question - is a CB Radio worth carrying?
My answer to that is YES, THEY SHOULD BE AN ESSENTIAL ITEM WHEN TRAVELLING ON ROADS WITH MINES IN THE VICINITY.

We often travel south on the Gregory Development Road (now Gregory Highway, I believe) & very wide loads are often encountered on it. The police (if they are involved), escorts always warn incoming traffic of the width of the loads - on channel 40.
We found on our very recent trip to Tasmania that escorts do not follow the same process - in fact they seem to have some very lax road rules down there!
Friends of ours refused to carry a small set that I gave them because of possible foul language & had two very close "incidents" involving a very wide load & a rogue truckie. They have since sold their van, stating it was too dangerous.

Yes, for those who are offended by the language, there is a volume adjustment. I've rarely found truckies in the bush swear & carry on - it mainly happens in & close to large towns.

Members, take note of both Cuppa & Mike's explanation above & carry a CB - you never know when you'll need it.

Thank you! Another question? I have a perfect spot on the top of my dash laying flat with the arial about an inch or so higher with the curly cord with Mike/speaker clipped on to the front of the dash vents. Is the arial ok to be flat?