helicopter noise UHF

[luvpsi]

hey guys i just installed my icom ic400pro and when the engine is running i get like a helicopter sound through it however when i turn it off i get crystal clear i tried moving the earth direct to battery however it still does it does this mean i need a sound supressor

[NissanGQ4.2]

Where are you getting the power from for the UHF?

[NissanGQ4.2]

Found below on this site: http://www.cbtricks.com/members/kd6tas/cbfaq4.htm

- Make sure you've completely installed your CB and the antenna is grounded properly. Check the amount of noise with and without the antenna connected. If the noise is greater when the antenna is connected, the source is probably the ignition system. If the noise remains unchanged after disconnecting the antenna, the source is probably in the CB's power supply.
- For ignition noise, there are several parts of the vehicle that can act like RF noise transmitters if not properly grounded. Check (and connect to ground on the chassis/frame, if necessary) the engine block, hood, muffler, and exhaust pipe.
- Ignition noise can be further reduced by installing "magnetic suppression" spark plug cables. (These are significantly more expensive than normal spark plug cables.)
- For power supply noise, check if you have a capacitor attached to your ignition coil, alternator, electric fuel pump (especially on late model Fords) and distributor. These can act as filters right at the source of the noise.
- Ensure that your antenna feedline and power lines are as far as possible from any of the noise sources mentioned above, especially the engine block.
- A shielded power cable can help as well. Make sure it is of sufficient gauge to handle your radio's power consumption and that the shielding has a good, strong connection to ground on the vehicle chassis or frame.
- Electronics stores such as Radio Shack sell low-cost power filters for noise-reduction purposes. But remember, you get what you pay for. Most comments on this newsgroup are that they are not as effective as the other measures above.

Of course, the best performance can be obtained from a more expensive radio with better noise suppression circuits. These measures, however, will improve the engine noise levels for nearly any mobile radio.

[luvpsi]

the power is coming direct from battery

[luvpsi]

ok i think i have found it when i rev engine the noise gets faster i had same issue with my old audio system in my commodore ute. i fitted a noise supressor and it went away im going to fit one of those and see if that works. i have also now found a bad a earth with some sort of wiring which does not seem to be the uhf as that was not connected at the time. when the engine is running my battery light and the little orange filter light on the dash are light but very dim when engine revs pick up they disappear. so i must have knocked something when i had dash apart a bit to fit UHF

[Yendor]

It sounds like you may have a problem with your alternator, possibly a weak diode or a bad connection at the alternator.

I would check all main earths on the vehicle including the one at the alternator.

You could also try disconnecting the alternator and then start the engine without revving it and see if the noise is still in your UHF.

[luvpsi]

yeah i was going to do that but the wiring to the alternator is shocking i have checked all earths also just not behind dash so i dunno but thats what i was thinking bad alternator but my stereo does not whine thats what makes me think wouldnt the stereo do the same if the alternator was shot

[Yendor]

Not necessarily, depends on the quality of the stereo and hows it's wired.

Your battery light being on dimly can be caused by 2 things, voltage drop due to old wiring or a weak diode in the alternator.

[luvpsi]

yeah but it only came on after wiring in the UHF and its not the only light thats on the diesel fuel filter light is also on dimly

[Yendor]

Possibly, you have only now just realised that the lights are on because of the problem with the UHF.

The fuel filter light is linked with the battery light, it's part of the check bulb circuit.

There's no guarantee the alternator has a problem. I'm just offering a suggestion from what you have posted.

If you think you have disturbed something while fitting the UHF then yes double check this.

I just can't think of what that might be seeing as you have wired the UHF directly to the battery.

[luvpsi]

i just went out there with a voltmeter at idle the battery is seeing 12.5v and when i turn lights on it drops to 12.2v and i read the alternator should be charging the battery at 14v and shouldnt drop when headlights are on so seems you are right yendor the alternator is on way out

[TheFlyingBadger]

so have you got the UHF sorted for tomorrow?

[luvpsi]

unfortunatly not completly jon still works just has a bit of interference on my end thats all but i can still hear you all

[TheFlyingBadger]

close enough for government work...

[luvpsi]

what you mean by government work

[TheFlyingBadger]

http://en.wiktionary.org/wiki/close_enough_for_government_work

means, "she'll be right....."

[luvpsi]

ah i see haha but it wont be down to that standard for long lol just need to get time to go get a sound supressor and new alternator now by looks of things

[the evil twin]

Possibly, you have only now just realised that the lights are on because of the problem with the UHF.

The fuel filter light is linked with the battery light, it's part of the check bulb circuit.

There's no guarantee the alternator has a problem. I'm just offering a suggestion from what you have posted.

If you think you have disturbed something while fitting the UHF then yes double check this.

I just can't think of what that might be seeing as you have wired the UHF directly to the battery.

What Rodney said...
but I'll go a bit further out on a limb and suggest you almost definitely have an Alternator issue with at least 1 phase out with a blown diode/s or maybe brushes. The other thing it could be is that you have disturbed the excitation wiring when fitting the UHF.

Anyway, whatever it is your battery isn't getting charged so I'd be carrying jumper leads till you get it sorted.

I'd also guess maybe 99% sure that fixing the Alternator fault will also solve your interference issue

Unfortunately I can't make the trip today or I'd have a quick look at it for you but would prob only confirm that the Alternator/Excitation wiring needs attention.

[luvpsi]

ok well here is the verdict the day went fine all day on the trip til on way home obvisouly alternator had died during the day casuing the battery to run flat on way home. i would indicate and the guages would jump around and all sorts then all of a sudden she shut off and had the typical flat battery sound when trying to start realising the alternator was stuffed completly i got her towed home as it was now dark and no headlights etc. so it was the alternator all along.

[Woof]

Just happy that you got home OK and had a great day out while I was at work..

[TheFlyingBadger]

Just happy that you got home OK and had a great day out while I was at work..

wayne. we thought about you *all* day mate :D

[Woof]

wayne. we thought about you *all* day mate :D

Yeah for sure you lot did.....................................Wayne/Doggy who..lol

[luvpsi]

fitted the new alternator today hopefully this fixes all my problems. bit hard to tell as of yet as my jumper didnt have the balls to crank her over so she is sitting on charge over night.