small crackle in UHF

If it's only there when driving it sound like it could be a loose connection.
Does it crackle when you rev the engine? Does it crackle through the speaker? Is it there when you transmit? or receive? or all the time?

Try shifting the earth point, or return the earth to the batt. but more info please, ie does the crackle frequency rise and fall with engine revs while mobile? or rise with road speed? or is it constant.

You could try jiggling all the connectors on the coax while it is running to see if its a bad / loose connector.

OK I have change the earth to the battery, still crackle on receiving. Could it me the movement of the aerial?? I have a 4.5db aerail on my bull bar, gme bracket, gme spring then the metal rod and then the aerial.?????

Try earthing both the radio chassis and the antenna base. Just use the flex from some spare coax.

From there you can try getting a RF choke from Jaycar/Dick Smith electronics. This is placed around the positve lead.

If all this fails, try and isolate the source of the RF interference. I am not sure of what sort of vehicle your are running. Could it been an electric motor, perhaps the fan (either engine or heater/airconditionor).

Cheers

Does it taste like chocolate?

Try unplugging the antenna. If the noise is there with the antenna plugged in and gone with it unplugged then it is antenna related. If it is still there without the antenna then it is obviously not the antenna.

I used to get park plug noise through my speaker in my Tx4400. Tried all sorts of things to get rid of it but to no avail. After a while though I realised the noise was gone and it never came back. Never did find out what was wrong but I'm happy now.

Crazie,

I got that too with my Uniden. Try driving out of the city - where there are no telegraph poles, underground or above ground electricity. It seems the telegraph wires and the sorts create this for me - that is why I was stationary no crackle, only when driving in city. Country a different matter. Try it you may be surprised. May be a way to eliminate the crackle in the city but I don't really care because don't use it in the city, only on trips.

Hope this helps

D-Jack

Crazie.
To find the sauce run your cb from a spare battery on the cabin floor, and then run a tempory coax from the bull bar over the top of the bonnet and through the passenger window, If you are running a seperate speaker from the main box make sure the wires to the speaker are twisted to cancell out any signals. Eric.

Adam... I had the same hassles... I moved the antenna to the roof on the drivers side and the problem was fixed....
It only used to crackle when the car was in motion... Use to drive me batty...
There is also a simple rule with UHF... "the higher the antenna the better"....

the higher the better?... not neccesarily true dukeatty. i'd personally re-check the soldered connection of the coax to the input at the back of the unit.

I get a bit of that in my Jack at times on HF radios - I put it down to a circuit running in the computer - have noticed that when all else is off, there is a current drain still running - I'm no techo, but the computer is digi in operation and so is the UHF radio ... might be something getting out - re HF (another story) - have found the Jack to be an interference factory.... all but given up on that issue. I do know that my TX3000 UHF hangs up on channel 35 when scanning because the Barrett HF remote head is too close ! So digi signals come out of that I guess. Whatever - I can only use bush logic !

G'day Crazie,
Was it you who wanted information on antenna separation??

On you current noise problem...have you got the mute/squelch set correctly??
If so..the symtoms appear to be antenna/ connection related.
Also, there has beenissues with the co-ax inside the earth tube- thats the tube the antenna whip screws onto.

Hope you can fix it
Signman

My UHF does this as well, only when the vehicle is in motion, and only when the radio is picking up a signal. To me it sounds different the faster the vehicle is traveling, and I put it down to interference from the ABS brake system, or something in the ECU that requires information on the vehicles speed.

I drive an auto 3.0 GU.

Cheers,

Muzz

A mate who's a Ham fanatic bought an Audi A6 diesel so that there wasn't any ignition noise but found that there was a whine on particular frequencies. Started pulling fuses and found that it was the self-levelling air suspension. Perhaps you could follow a similar route - at least if you can isolate the circuit/sensor that causes the noise then you might be able to re-route cables to get as far away as possible.

Good luck

Adrian