UHF's power in (watts) question

Submitted: Sunday, Jul 03, 2005 at 15:30
ThreadID: 24390 Views:11692 Replies:7 FollowUps:11
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I have a GME TX 3200 mounted in the car.

A mate wants to get a hand held UHF but we're not sure about the hipe re the 1watt or 2watt output etc etc.

Can someone pleaes explain to me in 'idiot' terms what it means. I know its about power which probably equates to better range but we only need to talk car to car.

What about clarity as well.

Thanks in advance.
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Reply By: Patrolman Pat - Sunday, Jul 03, 2005 at 15:35

Sunday, Jul 03, 2005 at 15:35
I've got a pair of 1W hand held and they are fine for car to car, talking a car around an obstacle, keeping in touch with kids.

2W should give better range in theory but it all depends on location, line of sight etc. I'd go the 1W s if they are cheaper as they'll be fine, clarity isd no problem with mine. They are Uniden 041s
AnswerID: 118638

Reply By: Mad Dog (Australia) - Sunday, Jul 03, 2005 at 15:47

Sunday, Jul 03, 2005 at 15:47
Not much difference between 1 and 2 watts Andrew. A doubling of power is equal to 3db, this is 3 tiny steps. I'd be inclined to base my judjement based on features, quality and price rather than power output when considering a 1 watt or 2 watt job. 5 watts would be a worthwhile improvement though.
AnswerID: 118639

Reply By: Member - Jeff M (WA) - Sunday, Jul 03, 2005 at 15:50

Sunday, Jul 03, 2005 at 15:50
The radio in your car is 5 watts, RF power is kind of exponential. ie 0.5 watt (most handhelds) to 5 watts will be a huge difference but 5 to 10watts won't be as effective.

You've also got to take into count the antennas as your rig will probally have a 6db gain antenna mouted externally (higher up and not enclosed by the metal cab of the car) which would over double it's effective output power.

The handhelds do work for car to car but about 500m is the range and if you have hills between you you'll get nadda reception.

I've got a couple of 500mw (.5 watt) handhelds for the kids and they work pretty well, we use 2 watt Unidens at work and they are pretty good and I've got a 5watt Uniden handheld for use when 4wding (standing outside the vehicle etc) and they all work ok, but even the 5 watt handheld is no where near as effective as the vehicle mounted radio with the same power.
AnswerID: 118640

Follow Up By: Member - Jeff M (WA) - Sunday, Jul 03, 2005 at 15:54

Sunday, Jul 03, 2005 at 15:54
Oh yeah as far as recomending one for your mate (to actually answer your question!) I'd tell him to get a real cheapie .5 watt (like a digitalk or similar) you should be able to pick one up retail for about $30, then save the rest of the money towards a decent car mounted jobbie.
FollowupID: 373804

Reply By: ripperGU - Sunday, Jul 03, 2005 at 17:11

Sunday, Jul 03, 2005 at 17:11
You can go with the best of both worlds- get an Icom IC-40S 5watt handheld and buy what they call a "service adapter" which screws into the antenna socket on the radio and has a BNC socket the other end. Then put a high mounted antenna on the gutter near the rear side of the front door (assuming you have a vehicle with a gutter!!) pass the antenna lead thru the door seal, and terminate near the radio with a bnc plug. I had my unit mounted in a home-made cradle attached to the side of the vehicle, high behind the drivers head out of the way, and used a mike/speaker attached to the seatbelt by its clip. Quite often the pricier handhelds have more features than some in-vehicle sets, and the added advantage of removal for walks etc., and theftproofing - what's not in the vehicle, the lowlife can't steal!!

El cheapo units of <1watt power are next to useless for convoying in bush situations.

AnswerID: 118643

Reply By: Member - Banjo The First (SA) - Sunday, Jul 03, 2005 at 17:50

Sunday, Jul 03, 2005 at 17:50
I'm with Ripper, and some of the other feedback - clarity doesn't seem to be a big issue - with UHF, you either have a signal or not - when it is there, its quite good mostly. I agree re the .5W, 1W and 2W etc re performance - high potential for disapppointment. I'd like a handheld but won't be buying anything less than the 5W - Prestigecom.net.au have the Icom IC-40S 5watt handheld just under $400 I think - all the 5W's are around that price + ...... they use a special inboard battery too - mains charging - (no AA cells etc). As said, if you buy a good handheld, you can pug an antenna in. I spoke with some road crews yesterday doing maintenance - the flaggies were using UHF - I got them quite some way off in undulating territory - called them up - they were using the Icom IC-40S 5watt handhelds !
AnswerID: 118651

Reply By: Member - Jimbo (VIC) - Sunday, Jul 03, 2005 at 18:38

Sunday, Jul 03, 2005 at 18:38
For car to car comm a $35, 0.5 watt job will do all you need. I bought a cheapie from Tricky's, Digitor T-584, which has a jack to allow running from a cig plug with an adaptor I already had.

It works so well I haven't got around to fitting my Uniden in the car.


AnswerID: 118658

Follow Up By: Mad Dog (Australia) - Sunday, Jul 03, 2005 at 19:01

Sunday, Jul 03, 2005 at 19:01
I'm with you on this Jimbo. I gave my yaesu with the power cranked down to 20mw to someone who didn't have comms last weekend in the bush, coverage was great for the 100 or 200 metres we required...yes only 20mw. imusty will confirm this
FollowupID: 373819

Follow Up By: Mike Harding - Sunday, Jul 03, 2005 at 20:29

Sunday, Jul 03, 2005 at 20:29
Agreed. I have some expensive commercial Maxon hand held units which are programmed to output 5W - couldn't get over 500m from them in a High Country situation a couple of years ago when I needed to.

For car to car go with low power cheapies - they'll do fine for a few hundred metres.

Keep in mind: high power Tx = short battery life.

Mike Harding

PS. Mad Dog - good trip?
FollowupID: 373834

Follow Up By: Mad Dog (Australia) - Sunday, Jul 03, 2005 at 20:51

Sunday, Jul 03, 2005 at 20:51
Yeah well I thought this guy may not shut up so I dropped it to 20mw to conserve our only batteries. As it was he was a bit mike shy but was starting to loosen up at the end of the day :)

Yeah good trip, bush camp with loads of fire wood, we named the camp timber loop because of the abundant firewood and the loop at the end of the track. imusty put the bus through a bit of water and up a moderately steep climb...he let out a yipeeee at the top. The bus goes well but wouldn't want to have to snatch it out.

FollowupID: 373838

Follow Up By: Bob of KAOS - Sunday, Jul 03, 2005 at 20:55

Sunday, Jul 03, 2005 at 20:55
There are some situations where the extra power may be an advantage (like triggering a repeater on a distant hill), but ultimately, UHF is line of site. So you are mostly limited by terrain, not lack of power.
I have a 5W Uniden mounted in the car, but I have three little hand helds which I lend to others in the convoy. These are completely adequate for most situations.
FollowupID: 373839

Follow Up By: Mike Harding - Sunday, Jul 03, 2005 at 21:06

Sunday, Jul 03, 2005 at 21:06
Mad Dog - so what frequency was iMusty transmitting on? :)

I have an Amateur Radio friend who you may well have heard on HF - he lives somewhat to the north of Melbourne and was telling me recently how he was chatting to the UK (on 20m) with 10mW (can't remember - might have been 100mW). However he does have an antenna system 195 feet high!

Don't worry about output power people - just get the antenna right.

Mike Harding
FollowupID: 373842

Follow Up By: Mad Dog (Australia) - Sunday, Jul 03, 2005 at 21:17

Sunday, Jul 03, 2005 at 21:17
>So you are mostly limited by terrain, not lack of power

Absoutely Bob. Small amounts of power on vhf/uhf go many thousands of K's in free space, sometimes aided by high gain antenna arrays but not always. I can communciate with the International Space Station with 20 watts VHF when it's on the horizon at a range of 2000k using a whip on the ute. Sat phones signal must travel a long distance also. I Don't know if the phone sats are orbiting or geostationary but a geo stationary sat has to be ..awe gee what is it...35,000k high...or is it 32,000
FollowupID: 373853

Follow Up By: Mad Dog (Australia) - Sunday, Jul 03, 2005 at 21:20

Sunday, Jul 03, 2005 at 21:20
Mike...cb ch 18...don't ask any more questions :)

That's true qrp but 195 feet high. I don't think the missus can climb that high :)
FollowupID: 373855

Follow Up By: Member - John C (QLD) - Monday, Jul 04, 2005 at 08:10

Monday, Jul 04, 2005 at 08:10
I am afraid I am going to have to disagree ith most of you.

Last trip we did a friend came along who didn't have a UHF radio, so he borrowed a 1w hand held.
We have a 5w vehicle mounted unit with an external aerial.
The third vehicle also had a 'standard' rig, 5w UHF and external aerial.

We found that the hand held internal in a car gave a range at most of 100m, down to 50m sometimes even when line of site travelling in convoy.

A real pain since the only vehicle that could hear them was the one closest. That vehicle then had to relay the message on.

A 4 , 5 or more vehicle convoy would be a real pain with that person missing out on a lot of comms. Worry is not knowing if they have heard the lead car on a trail obstacle, or turn instruction. (I know convoy rules should apply, but we all make a slip sometimes.)

As an experiment, we tried sending and recieving on the hand held back to a vehicle while walking in the bush. Level , but some scattered forest. Not dense rain forest. Range for clear reception went to about 150m.
Out to 350m, we could hear static, but not a voice.

If you want to use a 1w or 2w handheld for vehicle to vehicle, realise that tighter limitations apply and drive accordingly :-)
FollowupID: 373901

Follow Up By: Mike Harding - Monday, Jul 04, 2005 at 17:54

Monday, Jul 04, 2005 at 17:54
Hi John

I would hazard a guess that the 1W hand held radio is faulty in some way. One of the problems with the new breed of cheap low power UHF hand held CB radios is that they are designed and manufactured to a low price and, as such, I doubt much effort goes into ensuring they perform to their best capability when they come off the production line.

Providing you don't have hills or buildings between the two radios you really should be getting _much_ more from a 1W handheld that the numbers you mention. I assume the batteries were in a good state? And you should use either alkaline or NiCad/NiMh cells. Other types will tend to limit the output power.

I've just tried a test with a Jaycar hand held UHF CB, (DC-1040, which Jaycar bill as having a 1.5W output) using newish Jaycar AAA alkaline cells talking to my Maxon hand held (which is not really intended for CB) and that worked well across 500m of urban housing, a bit scratchy when the other end was operating from inside the vehicle but quite readable, audio quality improved when he got out of the vehicle, to be expected – both sets using standard antennas.

Mike Harding
FollowupID: 373983

Follow Up By: Bob of KAOS - Tuesday, Jul 05, 2005 at 10:01

Tuesday, Jul 05, 2005 at 10:01
the unit you had was obviously faulty. Our units work between cars up to about 3 km apart.
FollowupID: 374067

Reply By: Paul&Terri - Sunday, Jul 10, 2005 at 17:20

Sunday, Jul 10, 2005 at 17:20
As most people have indicated the output power does make a difference but it will be marginal. The biggest performance drop is with the antenna and because the hand held will be used inside the cab and without an external antenna connection it will definately not match the performace of your TX3200 with an external antenna, however for close proximatey convoy driving a hand held should suffice and it gives the added advantage of portability for recovery and bushwalking purposes.
One of the responses mentioned an effective doubling of power by use of an antenna of 6dB. This is not quite right. The Gain referred to in antennas relates to the pattern which the antenna radiates and depending on terrain the appropriate style of antenna will differ. i.e. in a flat area a high gain antenna will work best 9dB as opposed to a hilly area where a low gain 3dB antenna will out perform a high gain. A good middle of the road is a 6dB if you are intending in driving across various terrain types.
Mounting of your antenna is critical as well. If you want to get maximum coverage talking to your friend mount your antenna on your gutter or roof, not on your bullbar.
Happy chatting.
AnswerID: 119663

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