40 or 80 Channel UHF

Submitted: Saturday, Feb 04, 2017 at 10:51
ThreadID: 134241 Views:5246 Replies:9 FollowUps:7
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Do I transfer my existing 40 channel UHF To my new vehicle or buy and install
A new 80 channel ?
Ross N

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Reply By: Member - Tony H (touring oz) - Saturday, Feb 04, 2017 at 11:22

Saturday, Feb 04, 2017 at 11:22
Heard yesterday on ABC radio, ACMA have decided to abandon its plan to 'ban' the continued use of 40 channel CB's.
At last a common sense decision has been made by a government department.
So to answer your question.......go ahead and fit the 'old' radio ....you won't be pinged.
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Follow Up By: Zippo - Monday, Feb 06, 2017 at 00:26

Monday, Feb 06, 2017 at 00:26
If you check the other thread "Keep your 40 channel CB folks" (ThreadID: 134239) or check the ACMA website yourself, you will find that the ABC have mangled it.

ACMA have launched a discussion paper to ask (among other things) whether the planned June 2017 deadline for ending 40-channel equipment compliance should be dropped. It's only a discussion point.
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Follow Up By: tim_c - Friday, Feb 10, 2017 at 12:12

Friday, Feb 10, 2017 at 12:12
Maybe someone can educate me on this, but my understanding was that the 40 channel UHF used the same channel frequencies as half of the 80 channel UHF, just that the channels 41 to 80 were at frequencies between the 40-channel frequencies - in other words, channels 1-40 operate at the same frequencies whether the radio is 40 or 80 channel, but on an 80 channel unit, channel 41 operates at a frequency between channels 1 & 2, 42 between 2 & 3, and so on. If this is correct, how would ACMA even know whether you're using a 40 channel or 80 channel unit?
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Follow Up By: Member - Ian T6 - Friday, Feb 10, 2017 at 12:47

Friday, Feb 10, 2017 at 12:47
The problem is the transmit bandwidth. A 40 ch transmit band width is 25khz the new 80 is 12.5 so for example using a 40 ch st on ch 2 you will also be transmitting on upper half of 41 and lower half of 42. Easy for someone with equipment to see your transmit deviation (bandwidth ) is twice allowed.

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Follow Up By: Zippo - Friday, Feb 10, 2017 at 12:50

Friday, Feb 10, 2017 at 12:50
Tim, your understanding is correct.

The only way ACMA would know if a transmission was from a 40 or 80 channel set would be to monitor the signal's occupied bandwidth. And in the unlikely event there ever was an RI monitoring CB activity in your area, I'm sure there would be more significant issues detected out there than a wideband transmission.

------------------ alert - tech-talk --------------------------------------
For those intending to continue using a 40-chl set in a narrowband environment, having someone with the proper equipment turn down the transmitted deviation to match the NB figure would remove (a) the risk of detection and (b) the annoying distortion and mute chopping that typically results in a NB receiver from a WB signal. YOUR 40-chl receiver will still get crap from the 41-80 transmissions.
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Follow Up By: tim_c - Friday, Feb 10, 2017 at 13:00

Friday, Feb 10, 2017 at 13:00
Thanks Zippo - I read your comments in the other similar thread (Keep your old 40 channel CB) and think I understand the issues now - I'd previously thought there would be no problem. You might have go the impression from my reply above, but I'm actually not so interested in "trying to escape detection" but I don't want to be causing or receiving interference to/from other users (ACMA put their rules in place for good reason so the system works for as many people as possible).
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Reply By: Kazza055 - Saturday, Feb 04, 2017 at 12:07

Saturday, Feb 04, 2017 at 12:07
When I upgraded to my new D-Max, I had a new 80 channel UHF installed along with a new brake controller.

Probably would have cost more that they were worth to have someone remove them from the old vehicle.
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Reply By: Member - Stephen L (Clare SA) - Saturday, Feb 04, 2017 at 13:11

Saturday, Feb 04, 2017 at 13:11
Hi Ross

It will have to be done sooner ot later, so you may as well go the new 80 channel.
Also depending on how old your old unit is and what type of vehicle you have, there are more options to fit newer model radios compared to some of the real old dinosaurs.

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Follow Up By: RMD - Saturday, Feb 04, 2017 at 13:38

Saturday, Feb 04, 2017 at 13:38
I have both and as Stephen mentioned, features. The 40 can't scan the other 40 which people may be using and which you can scan then as well. Not essential but handy.
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Reply By: Robin Miller - Saturday, Feb 04, 2017 at 14:54

Saturday, Feb 04, 2017 at 14:54
It depends on your usage pattern Ross , there are reasons for and against.

Clearly if you wish to talk or listen across all 80 channels then that's the way to go.

In my case I always have 2 on at once , with the main 40ch one on a channel I use daily for local stuff , I never change its channel and I set it to CTCSS mute.

Its a 40 channel unit and 40 channel units sound a little louder than 80 channel units to both 40 & 80 channel radios and hence reception is better and the CTCSS muting functions work a little better.

For the second unit I have an 80ch one. It takes longer to scan 80ch than 40ch so if anyone goes this way get a fast scan model other wise you can scan and miss random calls.

Note 80ch units have a slightly longer range to other 80ch radios than 40ch items but the quality of reception is not quite as clear.

Note the above differences I refer to and small and usually less than putting the effort into mounting your aerial higher and free from obstructions.

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Reply By: Sand Man (SA) - Saturday, Feb 04, 2017 at 15:24

Saturday, Feb 04, 2017 at 15:24
After upgrading to a GME 80 channel unit, I noticed it was harder to hear a mate's 40 channel unit than another traveling companion's 80 channel unit.
Was receiving his broadcast OK but noticed "interference" which degraded the sound somewhat.

We all have 80 channel units now so there is no problem and we use one of the upper channels so there is less likelyhood, (at present) of having other parties on the same channel.

I chose to upgrade to an 80 channel unit as I wanted one with the speaker on the handset. My hearing isn't what it used to be.
I chose the GME TX3350.

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Reply By: Old 55 - Saturday, Feb 04, 2017 at 16:31

Saturday, Feb 04, 2017 at 16:31
I also brought the GME 3350 and we use the upper channels so gets you clear of the trucks and farmers [generally]. Love the controls on the handset and you can install the unit anywhere. I would go the newer 80 channel.
AnswerID: 608275

Reply By: Iza B - Saturday, Feb 04, 2017 at 16:38

Saturday, Feb 04, 2017 at 16:38
Low audio volume from a 40 channel set to an 80 channel set is a problem for me as the hearing is now an age related issue.

If travelling with a group that has 80 channel sets, you can get left out sometimes.

Not sure of the value of taking an old technology set out to put it in a brand new vehicle.

AnswerID: 608276

Reply By: Member - Phil G (SA) - Saturday, Feb 04, 2017 at 18:48

Saturday, Feb 04, 2017 at 18:48
I've wondered the same, but have kept my 40 channel Uniden UH088 set that I've had for about 15+ years so its been in a few vehicles. Good to know it will still be legal after July. Most of the people I travel with now have 80 channel sets and they have no problem hearing me and I have no problem hearing them.
I have also installed five of the new 80 channel sets (UH8080S and UH5060S) in the past year (all Uniden) and they have all transmitted well and received well.
The exception was one mate who had a GME 80 channel installed 3 years ago and his transmissions were low - nobody could hear him - he tried different aerials, different microphones and even sent the set back for testing without success. He gave up and bought an Icom. So there are some sets out there that have issues but I no longer blame it on the new narrow band 80 Ch radios.
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Follow Up By: 9900Eagle - Saturday, Feb 04, 2017 at 19:38

Saturday, Feb 04, 2017 at 19:38
Phil the low audio from a 40 to 80 is there, but a touch on the volume knob takes it out.
FollowupID: 878032

Reply By: Rangiephil - Sunday, Feb 05, 2017 at 09:49

Sunday, Feb 05, 2017 at 09:49
My experience suggests that the problem is not 40 to 80 channel as the 80 channels have a compensation circuit, but 80 to 40 channel is at about 1/2 the volume on the 40 channel receiver.

I learned this on Range Rover Club convoys and subsequent research.

If you have a mix of radios with a majority of 40channel sets they will complain about the low output on my 80 channel Uniden. All they have to do is increase the volume but this of course means that the 40 channel sets boom in. 80 channel sets receive at similar volumes for 40 channel and 80 channel, and I suggest that interference problems lie with the transmitting set , not the receiving set.
It is to do with the band being split so that 80 channel sets transmit at 1/2 the bandwidth of 40 channel sets as the 80 channels occupy the same band as the 40 channel sets..
I am very pleased with my 80 channel as it is a mini size which fits on the shelf over the winscreen vs my previous 40 channel Uniden which to be fair was 18 years old and still going strong, but sold with my old car.
Regards Philip A

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