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UHF aerials
https://auszookers.com/forum/viewtopic.php?f=37&t=54701		 Page 1 of 1
Author:  30ONA [ Wed Oct 18, 2017 4:43 pm ]
Post subject:  UHF aerials
I'm putting in a uhf radio.

But I don't have anywhere obvious to mount my aerial. No bull bar and the bonnet sill is not like other cars I've had.

How much would the range be effected if it was inside the cab, say hidden in the b pillar?

If not in the cab I'll have to get a special bracket to put it in the bonnet sill or a swivel joint and mount on the front bumper. I'd like to go on the tail gate but it's a lot of messing about for the wiring and I'd need to drill a hole in the door.

Any suggestions?
Author:  Gwagensteve [ Wed Oct 18, 2017 4:47 pm ]
Post subject:  Re: UHF aerials
Don't put it hidden by the B pillar. You risk blowing the radio up.

Tailgate will be the best option, even considering its a lot of work.
Author:  30ONA [ Wed Oct 18, 2017 6:13 pm ]
Post subject:  Re: UHF aerials
Why would the radio blow up?
Author:  Gwagensteve [ Wed Oct 18, 2017 6:18 pm ]
Post subject:  Re: UHF aerials
It’s complicated, but basically lots of metal around an antenna can load up the amplifier and kill them. The VIC police learnt this the hard way trying to setup concealed radios in unmarked cars.
Author:  Marck [ Wed Oct 18, 2017 8:19 pm ]
Post subject:  Re: UHF aerials
Uhf at 5 wats concealed in the b pillar won’t blow up the radio at 25 watts that public safety use the detrimental effects will be much worse. Yes it is a terrrlble idea and the reflected power will make it almost useless on transmit and mounting internally results in roughly 6db of loss on both transmit and receive unless you are only looking for very short range (hundreds of meters ) if you are happy to compromise on performance for ease of install use something like this

http://www.rfiwireless.com.au/mobile-pr ... ecoOrp_WhA

But make sure any tint is removed between the internal and external section.

The absolute best location for a uhf antenna is a hole drilled in the midddel of your roof and a 1/4 wave whip.

Basic rules to follow if you can’t / won’t do that. I wouldent.

Elevation is king the higher the better
Get good quality antennas my favourite is the RFI CDQ series that way you can unscrew the antenna whip when not in use.
Tail gate mounting again look for height mounting at the rear of the cabin reduces the forward performance and vice versa.
Always mount antennas on the right hand side trees don’t grow in the middle of the road all that often.
Radio power straight from the battery and earth to the chassis not to the battery.
Always have good earths on antennas and radio.
Easiest will be an L bracket on the bonnet edge
If you can’t terminate coax properly pay a man that can 99 percent of problems with radio performance will be people terminating coax poorly
A higher gain antenna isn’t always better. High gain for flat terrain or peak to peak transmissions. Lower gain for hilly tearin it’s all about radiation pattern plenty on google about it.

Good luck
M
Author:  30ONA [ Wed Oct 18, 2017 9:32 pm ]
Post subject:  Re: UHF aerials
Marck, thanks. I do have to point out though, in qld aerials must be mounted on the passenger side if on the front bumper. I would guess similar fire all states.
Author:  Marck [ Thu Oct 19, 2017 5:26 am ]
Post subject:  Re: UHF aerials
Yep I am in Qld mine is now mounted on the rh side of my roof rack on a folding bracket to get it out of the way. It was on the left hand side of my xrox bar as close to center as I could. Good antennas are not a cheep item so protecting them a little is worth it. The other option you have is a magnetic base antenna on your roof. Or just buy a 5w hand held.
Author:  shep [ Thu Oct 19, 2017 6:42 am ]
Post subject:  Re: UHF aerials
30ONA wrote:
Marck, thanks. I do have to point out though, in qld aerials must be mounted on the passenger side if on the front bumper. I would guess similar fire all states.


That would make my gov supplied work car illegal in qld, have 3 aerials on the roof and one on each side of the bulbar.
Author:  30ONA [ Thu Oct 19, 2017 7:14 am ]
Post subject:  Re: UHF aerials
shep wrote:
30ONA wrote:
Marck, thanks. I do have to point out though, in qld aerials must be mounted on the passenger side if on the front bumper. I would guess similar fire all states.


That would make my gov supplied work car illegal in qld, have 3 aerials on the roof and one on each side of the bulbar.

It Seems that way. Unless they have a dispensation.
Author:  30ONA [ Thu Oct 19, 2017 7:17 am ]
Post subject:  Re: UHF aerials
There are lots of fun rules for interpretation by us and the governing bodies to argue over.
Author:  Gwagensteve [ Thu Oct 19, 2017 8:35 am ]
Post subject:  Re: UHF aerials
This is old news. The devil is in the detail- “long range” refers to HF (rfds and amateur) antennas, typically the codan self tuning bases which presented a visibility risk due to their bulk. ~70mm diameter.

It does not refer to UHF antennas.
Author:  Marck [ Thu Oct 19, 2017 12:25 pm ]
Post subject:  Re: UHF aerials
you Will also find that the mounting position of accessories in the cabin will almost never meet ADR requiuremts either. unless they have passed impact testing they are not allowed to be mounted in the head impact zone in the front of the cabin. Or in any location where they will inter fear with the operation of an airbag. In most newer vehicles the only location that you can be fairly certain that you will comply with this is in the passangers foot well and not protruding above the console/tunnel. Or flush mounted in the dash itself.

Just mount the thing on the RHS of the bonnet about 1/3 back from the base of the screen. It’s usualy the best compromise for ease of installation performance and increasing the odds of keepin your antenna when off-road.
Author:  30ONA [ Thu Oct 19, 2017 6:25 pm ]
Post subject:  Re: UHF aerials
Marck wrote:

Just mount the thing on the RHS of the bonnet about 1/3 back from the base of the screen. It’s usualy the best compromise for ease of installation performance and increasing the odds of keepin your antenna when off-road.

Sure, but the seems on my model are weird. I'll need to find a new bracket.
Author:  Marck [ Thu Oct 19, 2017 6:43 pm ]
Post subject:  Re: UHF aerials
Where abouts do you live ? Oblis communications used to have a large range of mounts and such. They are at rocklea but I haven’t been in there for about 2 years so it could have changed.
Author:  shep [ Thu Oct 19, 2017 7:03 pm ]
Post subject:  Re: UHF aerials
30ONA wrote:
shep wrote:
30ONA wrote:
Marck, thanks. I do have to point out though, in qld aerials must be mounted on the passenger side if on the front bumper. I would guess similar fire all states.


That would make my gov supplied work car illegal in qld, have 3 aerials on the roof and one on each side of the bulbar.

It Seems that way. Unless they have a dispensation.


Thankfully where I live has rules that are a lot more user friendly then the nanny southern states.
We can also have dark tint on the front windows of a car.
Author:  MrRocky [ Thu Oct 19, 2017 7:17 pm ]
Post subject:  Re: UHF aerials
Keep in mind there is a formula to work out optimal cable length/antenna height if you are wanting maximum range.
Many of the massive bullbar mounted obes you see around are no better than a 6" tuned length setup.
Author:  shep [ Thu Oct 19, 2017 9:23 pm ]
Post subject:  Re: UHF aerials
MrRocky wrote:
Keep in mind there is a formula to work out optimal cable length/antenna height if you are wanting maximum range.
Many of the massive bullbar mounted obes you see around are no better than a 6" tuned length setup.



Need a SWR meter and every radio and aerial is different and needs to be adjusted on the car. Different aerials
work differently, have one at work that is 40mm round and 3 meters long and it can hit a repeater that is 180km from the office.
Author:  30ONA [ Fri Oct 20, 2017 6:53 am ]
Post subject:  Re: UHF aerials
So this info bought is second hand and the Muppet who removed it cut all the wires. I have a joint now in the aerial cable. Will I still get a few k's range? It's a 5watt uniden unit
Author:  fordem [ Fri Oct 20, 2017 1:00 pm ]
Post subject:  Re: UHF aerials
Just my $0.02 - buy a new antenna - you run the risk of destroying the transceiver output stage.
Author:  Marck [ Fri Oct 20, 2017 4:21 pm ]
Post subject:  Re: UHF aerials
How did you join the antenna cable
Author:  30ONA [ Fri Oct 20, 2017 5:07 pm ]
Post subject:  Re: UHF aerials
Marck wrote:
How did you join the antenna cable

Haven't yet. Want to run the cable first but got acoaxial joint from jaycar
Author:  Marck [ Fri Oct 20, 2017 7:31 pm ]
Post subject:  Re: UHF aerials
got A picture the sound of that worries me a littl even a link from the jaycar website will do
Author:  30ONA [ Fri Oct 20, 2017 9:23 pm ]
Post subject:  Re: UHF aerials
https://www.jaycar.com.au/coax-cable-joiner/p/PS0618
Author:  Marck [ Sat Oct 21, 2017 6:54 am ]
Post subject:  Re: UHF aerials
It might work but it probably be terrible . As suggested if you can spend a few bucks and buy a new antenna. Without a SWR meter you won’t have any idea how good or bad it is. Connectors like that are really only any good for receive only type devices like tv’s scannerers and so on.
Author:  30ONA [ Sat Oct 21, 2017 6:57 am ]
Post subject:  Re: UHF aerials
Thanks all for the warnings. Olbis is only one suburb from where I live so I'll make a visit to them.
Author:  Gwagensteve [ Sat Oct 21, 2017 12:10 pm ]
Post subject:  Re: UHF aerials
I think CB radio performance often turns into an irrelevant pissing contest.

A broken antenna isn't much good for anything, regardless of how many dB it claims on the box. For our (club) use, the use of CB's is only there if there has been a breakdown in convoy procedure. Even then, their use generally only confuses matters. When the UHF band became available, the trendy thing for our club members to do was buy these enormous 6dB+ ZCG fibreglass antennas. You normally now only spot these on B&S utes. These were (are) an awesome way of ruining a day out, by being the only thing you spend the day staring at, wondering if it's going to destroyed on overhanging trees.

I use a short stainless whip on a spring base. I'm sure the SWR is terrible, but I can't break it, it outperforms hand helds, and owes me so little money I don't have to care about it. I landed on this solution after breaking lots of antenna.

I carry a handheld in my glovebox with the intent of having a spotter use it, but in reality it never comes out - I prefer my spotters to use hand signals anyway, and they're rarely far enough away I can't hear them talking to me.

The idea that if you travel alone you can use a UHF to contact someone to bring help if there is some sort of mishap is pretty dubious. If you're hell bent on going out by yourself buy a satellite phone. UHF performance is just too hit and miss, particularly in the hills.

Which leaves UHF for chatter between vehicles in a convoy, or to listen to trucks. Neither of which require any sort of special performance.
Author:  ZUZUKI [ Tue Oct 24, 2017 10:19 pm ]
Post subject:  Re: UHF aerials
Like most things, it come down to a practicable, workable solution for the application.
The OP is unlikely to be doing much slow, hard core stuff & more likely to be doing faster (dare I say it?) dirt road stuff.
Signal range matters in some cases.
9 cars (7 of them Suzuki's) did a Cape York trip in July. The dust on the development road can be choking = cars spread out. On coming traffic details can be relayed by the lead car (who can see), or in overtaking a truck in dust situation, once the lead car is past, info can be sent back.
I don't know if the Sierra's & LJ have too much metal, usually went too slow to care about range, or were too noisy over corrugations at 80km/h to hear, but communication with them sucked. They missed out on some fun banter, decisions & safety info.
Yes, top wack out of a reasonable mid dBi range aerial might be only 12-15km, so not really useful for an emergency 'come & find me' but if you've only got 2-4km(?) of range, that can sometimes be not enough.
Rgs, Michael
Author:  30ONA [ Wed Oct 25, 2017 6:19 am ]
Post subject:  Re: UHF aerials
ZUZUKI, you pretty much nailed it. Long dusty outback roads. I spoke to Olbis. They believe the areal can be fixed. I also only thought about it the other day, but the cake was cut only about, 200mm from the end so rather than joint it I'll just put on a new connection and the cable will just be 200mm shorter.
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