80 Channel vs 40 Channel UHF questions

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BigDutchy
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80 Channel vs 40 Channel UHF questions

Unread post by BigDutchy » October 7th, 2014, 8:10 pm

Hi all

I bought one of these Aldi 80 channel UHF's. Although it was cheap and appears to work kinda OK it is not the most user friendly thing I have ever bought....anyway does a 80 channel radio need a different areal compared to a 40 channel UHF?

I have a Patrol for play and a Rodeo for travel. The Rodeo has the 80 channel thing but the 40 channel radio in the Patrol is so much easier to use. Is the 80 channel thing really that much of a "must have when travelling" thing?

What's your idea?

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chris_stoffa
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Re: 80 Channel vs 40 Channel UHF questions

Unread post by chris_stoffa » October 7th, 2014, 8:18 pm

Nope, my old 40 channel radio antenna has worked perfectly ok with two 80 channels radios since the changeover

The ease of use thing is often a make / model thing and a personal choice - I just ditched an Icom for a GME because I like the controls better. The Icom is considered a better radio.......... not if its controls pi$$ you off it ain't

You just have a greater choice of channels, maybe for a better chance of less traffic, just depends on who is on channel at the time
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BrAdAsS
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Re: 80 Channel vs 40 Channel UHF questions

Unread post by BrAdAsS » October 7th, 2014, 11:43 pm

The 40 channels and 80 channels both cover the exact same UHF CB frequency range. All they did to get 80channels was halve the width of each channel so they could fit twice as many in the same space.
Because the antenna is designed for the UHF CB it's using the exact same overall frequency range, any existing antenna is fine.

Older 40 channel UHF's use a wideband frequency which is 25khz.
Newer 80 channel UHF's use a narrowband frequency which is 12.5khz.

Therein lies a problem. Older 40channel UHF's broadcast at 25khz and can overlap the narrowband 12.5khz channels. This means older 40channel UHF's can cause interference to 80channel UHF users. 40channel UHF users usually come across louder than 80channel UHF's due to this.

There is so many more frequencies other than the CB that the consumer radio's won't do. I have approx 200+ channels in my UHF over 9 different groups... yellow cabs to the bus lines, QPS, Firecom, QAS, Fire and Rescue, SES, Tv station roadcrews, security companies, shopping centres, Brisbane Port repeater.. I use the multi-group-scan if I'm travelling and you soon find out if something is going on..

Rogers Cruiser
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Re: 80 Channel vs 40 Channel UHF questions

Unread post by Rogers Cruiser » October 8th, 2014, 12:53 am

Hay Bradass, how do you have the PMR frequencies? (Firecom, SES, F&R, ect. )

I wouldnt mind that setup myself.
'98-'06 - FJ-45 Ute fell over one day and didnt survive
'06-now - HJ-47 Troopy, restored and now daily driver.
'13-now - HJ-47 Ute, Farm fresh rust bucket, needs a restoration. viewtopic.php?f=22&t=152811

now - Off Road Box/Camper Trailer. viewtopic.php?f=134&t=153968&p=1792444#p1792444

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Dmaxqld
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Re: 80 Channel vs 40 Channel UHF questions

Unread post by Dmaxqld » October 8th, 2014, 7:30 am

He won't have any soon. Police are already on digital encrypted in Brisbane and all emergency services will be very soon. Then they will roll out digital across the state in the next year or so.

Rogers Cruiser
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Re: 80 Channel vs 40 Channel UHF questions

Unread post by Rogers Cruiser » October 8th, 2014, 12:28 pm

Ha, we got told that our (NSW RFS) PMRs would be encrypted digital years ago!
'98-'06 - FJ-45 Ute fell over one day and didnt survive
'06-now - HJ-47 Troopy, restored and now daily driver.
'13-now - HJ-47 Ute, Farm fresh rust bucket, needs a restoration. viewtopic.php?f=22&t=152811

now - Off Road Box/Camper Trailer. viewtopic.php?f=134&t=153968&p=1792444#p1792444

Dont listen to me, Ive got an opinion on everything!

BrAdAsS
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Re: 80 Channel vs 40 Channel UHF questions

Unread post by BrAdAsS » October 9th, 2014, 4:05 pm

The QPS still use analogue, all around the goldcoast, south side, northside all the way up to noosa you can listen to it right now.

The UHF in my vehicle is limited to 512 channels and does everything from 450Mhz to 520Mhz, rx and tx.
Your UHF needs to support those receiving frequencies, then you have to program the channels in - if your UHF can do that.

Link to commercial SEQ frequencies
(In the top left, if you click Queensland and on the right under Agents, select whatever you want.. voilla.

Thedonsway
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Re: 80 Channel vs 40 Channel UHF questions

Unread post by Thedonsway » July 22nd, 2016, 6:32 pm

If anyone bothered to read the actual frequencies of both 40 and 80 channels, they would find that 1 to 40 use the exact same frequencies on both with 25.0 splits. 41 to 80 uses various split frequencies above 477.400. So realistically, all they did was add more channels, not split from 25 to 12.5 like they want people to believe.
http://uhfcb.com.au/80-Channel-UHF-Information.php
http://www.uhfcb.com/40-Channel-UHF-Infomation.php
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Oldholdennut
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Re: 80 Channel vs 40 Channel UHF questions

Unread post by Oldholdennut » January 11th, 2018, 10:24 pm

"If anyone bothered to read the actual frequencies of both 40 and 80 channels, they would find that 1 to 40 use the exact same frequencies on both with 25.0 splits. 41 to 80 uses various split frequencies above 477.400. So realistically, all they did was add more channels, not split from 25 to 12.5 like they want people to believe."
You might want to read it your self again. Yes channels are identical from channel 1 (476.425Mhz) to 40 (477.400Mhz) in frequency only, The old 40 channel units did use the 25kHz but the new 80 use only half that at 12.5kHz, in effect channels 41 onwards use the new space between the old channels. Simply channel 41 is actually old channel 1 plus a half channel then 42 is old 2 plus a half channel etc all the way to channel 80 which is old channel 40 plus a half channel 12.5kHz

channel 40 is 477.4000mHz
channel 80 is 477.4125mHz which is that extra half channel added.

The Bandwidth has been changed allowing us to double our channels over effectively the same frequency range. It works like this:
The old radios use a channel that is 25kHz wide (that's its bandwidth)
New radios use channels that are only half as wide 12.5kHz (25/2=12.5 kHz bandwidth)
Picking a random channel set;
So channel 14 is 476.750Mhz, on an old radio with a wide 25kHz bandwidth, the channel basically used 12.5kHz below and 12.5kHz above 476.750 to carry our 4x4 chatter so the whole channel is from 476.7375 to 476.7625 which is 25kHz . When we halve that the channel width to 12.5kHz (half of 25) it is now only from 476.74375 to 476.75625 which is a band of 12.5kHz. This leaves a gap between the old channels of 12.5kHz... insert new channel here! Pretend there is a fence between these channels. We have divided our 25kHz blocks into half, put a new fence down the middle, and put a new channel on the old fence......

25kHz 12.5kHz

Channel 13-----476.7250------------------------------Channel 13----476.7250---------------
---------------------------------------New Fence-------------------------------------------------------------
Old fence-------476.7375----------------------New Channel 53----476.7375----------------
---------------------------------------New Fence-------------------------------------------------------------
Channel 14-----476.7500------------------------------Channel 14----476.7500---------------
---------------------------------------New Fence-------------------------------------------------------------
Old fence-------476.7625-----------------------New Channel 54----476.7625---------------
---------------------------------------New Fence-------------------------------------------------------------
Channel 15-----476.775--------------------------------Channel 15----476.7750---------------

Old channel 13 with a 25kHz bandwidth will interfere with new channel 53 etc - So its time to retire the old 40 channel radios.

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