UHF range

Submitted: Thursday, Mar 02, 2006 at 21:02
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Gday all, just after some opinions on this little matter.

Just did UHF range test with my Brother who had an El-cheep0 Handheld .5-watt UHF lying around and we thought we would see what sort range it had around the suburbs.

The best we got was around 700Metres when it started to become too crackly to understand.

I went up a hill and along the top following the road in an S shape then down the side where I lost him completely.

No surprise really. What concerned me was with my 5Watt in car unit he completely lost me as well, until I got back in front of the hill and within 900 metres of his unit.

This sounds a bit off to me, I was expecting to lose him rather quick but I thought that his unit would still pick up my transmissions no worries in that sort of range, or am I way off base on this.

The last time I rely used the UHF for talking at any sort of distance was 8 months ago, and around the metro aria I was easily getting more than 900metres out of it. In the country I often have it on CH40 and will pick up roadworks and other chatter from way out.

So is something a miss or am I way off base in my thinking.
It’s a Unden Unit UH-89 running a Mobile One 920mm antenna B/Bar mount, it’s a 4.5Db or 6Db module can’t remember as I brought it 4 years ago.



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Reply By: Wayne (NSW) - Thursday, Mar 02, 2006 at 21:16

Thursday, Mar 02, 2006 at 21:16
Exploder,

Keeping it simple.
The radio needs to see the other radio. If you were on top of a big hill and I was 30klm away on top of a big hill then we could talk.
If you were around the other side of a big mountain and I was on the other side 1lkm away we could not talk.

A .5w you could shout just as far. 5w and you have the range if you see the other radio.

This is very simple expiation but it will you an idea of how it works.

Wayne
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Follow Up By: Exploder - Thursday, Mar 02, 2006 at 22:08

Thursday, Mar 02, 2006 at 22:08
Follow you their Wayne.

Might try a straight line test over a few K’s to see it he can hear me transmitting, I am not expecting to be able to receive him at distance, But if he can’t pick me up there might be something a miss in my system.

That or do a radio check on Ch8.
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Follow Up By: Mad Dog (Australia) - Thursday, Mar 02, 2006 at 22:17

Thursday, Mar 02, 2006 at 22:17
Basically that about it but refraction and bending does occur that can make UHF signals heard in the most unlikely spots.

I can communciate across my town with a 5 watt handheld a distance of 5 or 6 k to a guy with a base antenna up 6 metres high.....it's rather scratchy but it makes it. I have also used the same radio to communciate with him very well indeed at a distance of 60 k, the difference is I was up a fire watch tower on top of a very large hill.
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Follow Up By: Exploder - Thursday, Mar 02, 2006 at 22:31

Thursday, Mar 02, 2006 at 22:31
Yeah about the longest distance I have coved with my unit is 20K’s car to car on the way to Coral bay in northern WA and that was the Verry most we could manage.

But have managed a few K’s in the suburbs around Perth before, This is why when my Transmission only got 900metres I thought something was up.
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Follow Up By: Mad Dog (Australia) - Thursday, Mar 02, 2006 at 22:45

Thursday, Mar 02, 2006 at 22:45
At these freqs there's lots of things out of our control that influence the signals, density of trees and buildings play a big part, terrain, the weather and temperature.
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Follow Up By: Nick R - Thursday, Mar 02, 2006 at 23:10

Thursday, Mar 02, 2006 at 23:10
Unlikely spots alright, got from the house here in western Vic and spoke to a bloke in a landcruiser on King Island, a neighbouring house got to Tassie one day, admittedly with an aerial up 60 feet. Best range seems to come at the tail end of a high pressure system moving through. In my experience the main impedemants are hills, trees & cliffs.
NickR
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Follow Up By: Mad Dog (Australia) - Thursday, Mar 02, 2006 at 23:19

Thursday, Mar 02, 2006 at 23:19
Well you're talking about ducting or a temperature inversion Nick. Signals can carry be carried across to the other side of the continent .
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Follow Up By: Nick R - Thursday, Mar 02, 2006 at 23:27

Thursday, Mar 02, 2006 at 23:27
Incidentally at the same time the tv reception is r s even the digital is no good, something to do with too much signal???? happy enough to turn it off.....
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Follow Up By: Mad Dog (Australia) - Thursday, Mar 02, 2006 at 23:47

Thursday, Mar 02, 2006 at 23:47
Interference from distant transmitters on the same frequency Nick.
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Reply By: Brett_B - Thursday, Mar 02, 2006 at 21:58

Thursday, Mar 02, 2006 at 21:58
If you did your test in conjunction with another quality in car unit the results would be totally different, the .5w can only hear as far as it throws :-)
AnswerID: 158196

Follow Up By: Member - Andrew W (VIC) - Thursday, Mar 02, 2006 at 22:07

Thursday, Mar 02, 2006 at 22:07
You sure thats right Brett? I have a 1w hand held and sure as hell can hear more than can hear me.
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Follow Up By: Mad Dog (Australia) - Thursday, Mar 02, 2006 at 22:19

Thursday, Mar 02, 2006 at 22:19
Handhelds are usually built with a very senstive front end to make up for the short stubby antenna, they usually hear lots more than they can get back to.
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Follow Up By: Brett_B - Friday, Mar 03, 2006 at 20:38

Friday, Mar 03, 2006 at 20:38
Hi Guys,

That sketchy reply up top is what was basically explained by a CFA Coms guy, to me and my experience with these little radios it seems to have merit, when I use my GME TX 610 together GME 3400 I basically find when they cant hear me I cant hear them, or is it the other way around :-) in either the desert or mountains. I also have 2 cheap .5W UHF, same with these I find.

I however am no expert at this, I'm just going on what I heard.

Brett
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Reply By: arthurking83 - Thursday, Mar 02, 2006 at 22:05

Thursday, Mar 02, 2006 at 22:05
Hi Exploder,

I'm no radio comms expert...but my (very limited)understanding of how radio and radiowaves work is......

When you said you tested the range of the .5W handheld with the 5W car mounted radio, it kinda occured to me that regardless of how powerful your car radio is going to be, it wasn't going to hear the very soft .5W transmission of the little handheld! The advertised power rating is for the transmit power of the radio.

The receive power is less than half that on most car mounted radios.
(and I think about 1/10th on some handhelds, with a switch to increase the recieve sensitivity on some??
I'm guessing around 1/2W - 1W, for most car radios(an expert will confirm/rebuff this)

So unless the transmission is powered higher to clear the hill, then not many devices will hear that 'whisper' of a transmission trying to overcome the hill!!

Even if you had a reciever that had 5W reieve ability, it would almost certainly need lots of filtering to remove any interference it will also pick up from various sources in the vicinity!

If your test Tx radio was a 1W or full powered 5W source then you may have heard it just a little bit longer, DOWN the other side of the hill!

If you can get your hands on a scanner, try using that next time too....
I think they have higher powered receivers, you may find th escanner may have heard the .5W transmission just a bit better(??)

then there are other environmental factors to consider too, like interference.........

......waiting now for the comms experts, to come along and 'shoot me down'......!
AnswerID: 158201

Follow Up By: Exploder - Thursday, Mar 02, 2006 at 22:24

Thursday, Mar 02, 2006 at 22:24
The low power unit was stationary, standing on the front lawn, and I was mobile in the car with my 5W system, what struck me as odd was that as soon as I lost him he basically lost me too, even when I had come back around from the other side of this hill, the range on the 2 unit’s was almost identical. But ones worth like $20 and the other $500 when I brought it 4 years ago.

Might Jump on CH8 tomorrow and do a Radio Check.
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Follow Up By: rickwagupatrol - Thursday, Mar 02, 2006 at 22:56

Thursday, Mar 02, 2006 at 22:56
mate, ch 8 is a repeater, you will be heard half way around the city.
a handheld has a limited range, your car jobbie has a greater range.
but, go around a hill or through dense trees and they both turn to crap real quick.
i have a GME 4400 in my truck and can hear some blokes for miles, others i lose as sonn as they go into anywhere there is alot of tall buildings or trees or,,,well the list is pretty big.

rick.
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Follow Up By: Exploder - Thursday, Mar 02, 2006 at 23:07

Thursday, Mar 02, 2006 at 23:07
Ok cool, probably just where I was that was the problem.
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Reply By: Member - Doug T (QLD) - Friday, Mar 03, 2006 at 00:20

Friday, Mar 03, 2006 at 00:20
Well i guess there will be a lot of knockers on this one but on a few occasions between Hughenden and Julia Creek Richmond area just after sun up i was escorting trucks west on the Flinders Hwy and we were talking to and hearing trucks on the Landsborough Hwy near McKinlay , i checked the GPS for a straight line to Kynuna and it was 208 Klm, now this don't happen often ,The first time i experienced this freak reception was near Julia Creek back to the Shell at McKinlay and that was 108 Klm, please feel free to Call McKinlay Shell if you have any doubts'
About your hand-held well it depends on what power it is putting out and its quality,el-cheapo won't get farnor will it recieve well either, but a good DSE or Uniden with 5watts and you'll be surprised how far they do get out,
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Reply By: Darian (SA) - Friday, Mar 03, 2006 at 09:08

Friday, Mar 03, 2006 at 09:08
UHF's aint UHF's too Ex (as in oils aint oils) - re your in-car unit (have not tried the low power handhelds) - I recently upgraded my car unit to an Icom 400 pro - putting all the bells and whistles aside (its like a PC - there are configs and functions in there that go on for ever) it out performs the older GME unit by light years (but they are both 5W UHF's) - even though the GME had a premium antenna and a tidy setup. Innovations in radio design must be the go I guess.........
AnswerID: 158291

Follow Up By: Dean (SA) - Friday, Mar 03, 2006 at 12:33

Friday, Mar 03, 2006 at 12:33
Hey Darian,
I can easily speak to a fella over at Ardrossan on the GME 5w, the other day I had a yack on the uniden .5w to the same bloke, I suppose other than shark alley there's not much between us.
Dean
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Follow Up By: Darian (SA) - Friday, Mar 03, 2006 at 13:36

Friday, Mar 03, 2006 at 13:36
Indeed Dean - line of site plus water underneath is a powerful combo - HF of course bounces up and down as it travels long distances, and water improves that lower bounce too, by a lot it seems.
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Follow Up By: Member - Doug T (QLD) - Friday, Mar 03, 2006 at 23:24

Friday, Mar 03, 2006 at 23:24
Hi Darian
just read your reply about having got an Icom , i have one too and its a good radio, recieves good and transmits with a clear un-distorted reception,BUT when playing around in the miriad of settings make sure you don't end up having a little icon flashing in the top left corner, if it is then the radio is more than likely sending out a pulse about every 45 seconds, you won't know or hear it but it annoys the crap out of ppl you could be travelling with. Refer to owners manual
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Follow Up By: Mad Dog (Australia) - Friday, Mar 03, 2006 at 23:27

Friday, Mar 03, 2006 at 23:27
What's the purpose of the pulse Doug ?
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Follow Up By: Member - Doug T (QLD) - Friday, Mar 03, 2006 at 23:33

Friday, Mar 03, 2006 at 23:33
I would not have the faintest idea why it pulses for just that when mine did it i had the truckies going on about someone jabbing the button coz i wasn;t doing anything it didn't register but a few weeks later got near the same truck and linked it to my radio so i done some looking and we matched it with the blinking icon with a lot of button pushing i stopped it , reason for it unknown..... maybe if ya died in the bush ???? lol
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Follow Up By: Mad Dog (Australia) - Saturday, Mar 04, 2006 at 00:34

Saturday, Mar 04, 2006 at 00:34
ok I thought the manual may have had an explanation.
It would be good if it started in enough time for the Ambulance to arrive :)
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Follow Up By: Darian (SA) - Saturday, Mar 04, 2006 at 09:31

Saturday, Mar 04, 2006 at 09:31
Will have a look at the pulse thingy - I've seen the icon come and go while doing some setup - as said, its a very sophisticated radio for the money - can handle a lot commercial channels at 25W too... but I'm only into CB - I've set mine up for CTCSS on one channel and selcall - both for comms to my handheld....... yet to test it fully. One thing is for sure - the Icom manual may be accurate but its not very bhelpful to novice owners at all - too much is assumed on the part of the owner - a lot of jargon and geekspeek in the generally brief instructions.
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Reply By: Rosco - Qld - Friday, Mar 03, 2006 at 09:41

Friday, Mar 03, 2006 at 09:41
G'day Exploder

One issue which doesn't appear to have been covered above relates to your antenna.

You mention a 920mm. I reckon if you had a 150mm unity gain jobbie you would have got him over the hill.

Taller antennae transmit in a flatter narrow pattern perpendicular to the antenna over a greater distance, whilst shorter ones transmit in a rounder ball type pattern over shorter distances. Hence better for hilly areas or in convoy.

This info is available on one of the web sites, but I don't recall which (perhaps GME)

Food for thought.

Cheers
AnswerID: 158302

Reply By: Scoey - Friday, Mar 03, 2006 at 13:23

Friday, Mar 03, 2006 at 13:23
HI Exploder,

I have been in almost thje exact same situation. I have the Uniden 0.5w handhelds and mate has Uniden in car 5w (Sundowner UH-012???). In convoy it's great, if I get a bit ahead of him on a dusty road he loses me real quick but I can hear him clear as a bell. Chuck us into some hilly stuff and all things are equal - they're both useless!

Cheers
Scoey
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