uhf crap sending signal

[Stropp]

hi guys, i an having trouble with the sending on uhf, receives fine but the vehicle behind cannot hear if its out of more than 20mtrs range when we send, i have replaced the aerial but it hasnt made a great deal of diffrence, any help appreciated.

[DX grunt]

Where's your aerial.

I'm not saying that this is the problem, but UHF is designed for line of sight.

If it's not too much trouble, you might want to try moving it. The higher it is, the better reception you should get.

My 2c worth.

Rossco

[Stropp]

on the bullbar normal spot rosco, i was thinking that, but why do others have no problem in the same mounting on the bullbar, it does extend slightly above the roof but not heaps.

[DX grunt]

Is it the same vehicle behind you that has trouble receiving you? It may be it's their CB playing up and not yours?

Mine sits on a magnetic base on the bull bar and I don't appear to be having any probs.

Have you checked the coax for kinks and breaks?

Rossco

PS: 20m is waaaaayyyyyy too close to sit behind somebody, at speed!!!

[Stropp]

rosco, not at speed mate just up at the power lines and it is any vehicle behind, will pull the coax out and check it thx.

[DX grunt]

It might also be the actual microphone/cord. Not savvy enough to know what I'm talking about, but it's a thought.

I'm assuming that everything is screwed in properly and tightened - ie no loose connections?

[Aquaman]

It does sound very odd that you can hear clearly and but they can't hear you. Are you sure the person you are talking to is not just taking the %$#*. Is it with the same person everytime. Do they know how to use their gear. Is the problem with their gear. Even a little cheapo handheld is going to be able to go 20m in most situations.

If you are convinced that it is a problem with your gear the next step seeing as how you have already done the antenna (you did get the correct type for the terrain and ground indepedant?) is to check the coax. One of the connections might have come loose or they might not have been done properly in the first place (it might pay to do some fresh connections) or it might have gotten damaged somewhere.

[Aquaman]

Sorry if i asked stuff that was being answered while i was typing. Even though it is just above the roof line it should still be okay for the convoy distances you are talking about. Yes i know the higher the better but in dense bush having it too high is only going to mean damage.

Like Rosco said make sure everything is tight.

[Stropp]

yes thanks guys, will pull the coax and check everything, its different people all the time, they can hear interference but not here what we are saying. need to check the whole setup and try from there. thanks again

[DX grunt]

yes thanks guys, will pull the coax and check everything, its different people all the time, they can hear interference but not here what we are saying. need to check the whole setup and try from there. thanks again

Another thought....... Have you actually gone to the other vehicle and got somebody to jump on your mike and given a test call, etc, to see if you can tell where/what the interference is coming from?

[DX grunt]

a DAQ......You don't drive at Mach 1 with all the windows wound down and the rock box cranked up? LOL. Sorry, couldn't resist.

[Stropp]

no the young fella may but not me :)

[megatexture]

is it just the cars behind or infront aswell sounds strange? if you cant be herd then it must be on your side my uhf can pick up other ppl even with out an antenna connected but doubt it will send not that ive tried sending without one. the antenna must be faulty or coax not fitted correctly . check the coax cable comeing from the antenna also as ive had some ass pull the cord out of one of my antennas at a train station ive since fitted them in copper pipe and fastend it to the bull bar.

[Finly Owner]

Ok read all the above before commenting.

Firstly is a shop bought set? Matching mic to radio?

Do you have another aerial(AM CB, Sat Phone) right next to UHF aerial with that set also turne on?

Have you made sure earth on power feed lines has not come loose, or the earth on aerial?

Is the mic rattling when being used?If so it could be the mic needs replacing.

And just check aerial and mic plugs are tight on set.


Tim

[malcolm]

Hi, suggest you check your electrical connections - It's not that unusual for a radio to receive but not transmit - transmitting takes more power than receiving - so a poor connection or earth may allow you to receive but not transmit . Also, I think, pushing the speak button, ie transmitting. without an aerial connection can damage your radio - check the manual . Hope this helps !
cheers

[Garry52]

Is it an old radio or newer one? Distance shouldnt be a problem, and where the antenna is mounted is ok. If its receiving ok but not transmitting properly could be a problem in the transmit part of the radio.

[Maxhead]

If you are breaking through to them but all they can hear is interference would mean you have enough power to reach them but they can't understand because of interference. I would try another mic, if you can borrow someones and test.
Simple method of ilimination would be to try a mic and if it is no it then try and swap the radio(if you can). At least you will know if its the radio or mic or coax/aerial
What sort of interference is it?

[DX grunt]

I had the same problem the other day. I turned the UHF on and put it on scan. I tried to transmit, with the radio automatically returning to Ch 40 and, nothing. I unscrewed the mike, then put it back in, and pressed the button, and it worked. Not sure why, because I haven't touched anything previously, but it worked. Try that.

[97_gq_lwb]

Sure it isn't a simplex duplex error lol

At that distance they probably hear you bleeding through .

[Bloodyaussie]

I had the same issue with my new GME and even went back to the store to check it all was wired up correctly and everything seemed ok, It turns out it was a dodgy sender unit inside that had carked it.

It could be heard up to 100m away but after that it was dead.

The unit was an ex display and am not sure if it was powered up with no aerial attached and the mic used, as we all know you cannot transmit without an aerial attached as it can damage uhf.

It was sent back to GME and all was fixed.

[Stropp]

Thanks for the advice, it has had all earths cleaned to make sure it's ok, only other thing is mic but it seems to be hard wired, will have to have a closer look!

[04OFF]

on the bullbar normal spot rosco, i was thinking that, but why do others have no problem in the same mounting on the bullbar, it does extend slightly above the roof but not heaps.

When you say normal spot, do you mean on the flat main section, or on the hoop/tube part (pic would be good)

[Stropp]

Talked to the radio repair man and he said it would be a faulty send transistor and $120 to fix so I bought a new 80 Chanel radio.

[97_gq_lwb]

Did you have the Ariel an cable checked to make sure it doesn't happen to the new radio.

[Stropp]

No mate the new one worked perfect on the old ariel, I bought a new Ariel anyway and works fantastic, had a chat to the young blokes mate who lives about 5 k's away.

[97_gq_lwb]

Usually the transistors are burn't out by a dodgy aeriel over time always pays to have them checked on a swr meter to be safe rather then sorry.

[GQ TANK]

To Check a rig:-

1. Visual check of the antenna, cable wiring connectors mic - anything obious.

2. VSWR check - this will confirm that the cable and antenna is ok, and that the radio is trasmitting the correct power.

3. Still a problem, the unit is pulled and put on a bench and connect to a service monitor. Power, deivation receiver sensitiity et is checked.

The most common problem is always connecotrs, cable run and antennas


(Im a radio tech)

[Finly Owner]

To Check a rig:-

1. Visual check of the antenna, cable wiring connectors mic - anything obious.

2. VSWR check - this will confirm that the cable and antenna is ok, and that the radio is trasmitting the correct power.

3. Still a problem, the unit is pulled and put on a bench and connect to a service monitor. Power, deivation receiver sensitiity et is checked.

The most common problem is always connecotrs, cable run and antennas


(Im a radio tech)Interesting, how do you VSWR meter a UHF ariel? As I understand it, VSWR measures strength in gain wave length gain to to particular radio set and ariel on attached to a particur location and also can be altered according to the plane set with the ariel?

Now isn't UHF a point to point signal, not a wave signal?

So therefore a Db gain reading wouldbe needed.

And further more, with VSWR tuning a AM set you tune the SWR by trimming the correct ariel to get that elusive 1.1.. But how do you tune the uhf Ariel?



Tim

[Agronaught]

What type of coax and how long ?

The usual coax I see people use on their installs isn't rated for UHF frequencies and the attenuation on that cable means you could be losing most of the signal before it even reaches the antenna. This won't be picked up by checking the SWR, it will show up if using a power meter at the antenna.