27MHz noise

Submitted: Sunday, Aug 10, 2003 at 18:44
ThreadID: 6483 Views:1773 Replies:8 FollowUps:1
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I've installed a GME TX835 27MHZ radio in my new Toyota L/C T/D.
Works fine when the engine is not running, however, when at 1500 plus RPM an incredible noise comes thro and the squelch has to go right up.
Power is via an extra heavy duty cable to a fuse box, then to the radio.
Earth is to the body.
Is anyone able to assist?
ParsoParso
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Reply By: Mixo - Sunday, Aug 10, 2003 at 20:54

Sunday, Aug 10, 2003 at 20:54
If you search for some posts on HF in this forum you should get plenty of clues. There has been a lot of comment.
Far as I know you are in deep cack...my Jack has it bad but Toj is reputed to be worse...the electronic circuits and wheelygigs running your donk are putting out lots of strong HF interference. Apparently the car makers don't care. Too hard to cure, so they just make out they don't know. Some of the new EFI's
are the same. Many long distance HF users (same band as your CB) have to stop and turn off before using the radios these days.If you have a UHF it should be un-affected - different technology.Gotta have red sand on those boots !
AnswerID: 27379

Reply By: Member - Bigbear - Sunday, Aug 10, 2003 at 21:44

Sunday, Aug 10, 2003 at 21:44
Hi Parso

Had a similar problem just recently on my mates Rangie. We tried all sorts of things and it seemed to come down to two things.
1 The radio was not adequately earthed
2 The source battery was not fully charged- This was a real surprise as he had the battery on the charger for some time before we tried. Only after recharging the battery for several hours were we able to get rid of the pulsating noise.
Dunno if you have tried these

CheersBush Bappo's 4WD Club
Get out there & have a look
AnswerID: 27389

Reply By: Truckster (Vic) - Sunday, Aug 10, 2003 at 23:24

Sunday, Aug 10, 2003 at 23:24
What about an inline suppressor??
AnswerID: 27404

Reply By: wazza - Monday, Aug 11, 2003 at 10:40

Monday, Aug 11, 2003 at 10:40
Yeah, a noise suppressor and my tip it is possibly the electric fuel pump causing the interference. But could be wrong.... I usually am and it is the last thing I look at. GME site also says the TX835 has built in suppressor to take most noise out.

TX835

AnswerID: 27421

Follow Up By: Parso - Monday, Aug 11, 2003 at 11:56

Monday, Aug 11, 2003 at 11:56
Thanks guys!
I will give the noise suppessor a go.
Both Tandy and Dick Smith are out of stock, however, I found one at Jaycar Electronics.Parso
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FollowupID: 18879

Reply By: Mixo - Monday, Aug 11, 2003 at 12:02

Monday, Aug 11, 2003 at 12:02
Worth a try re the supressor - been there with the Jack but no improvement. My guru said it wouldn't work - he was right - said that the HF radios have very good 'ears" and pick up everything, including the donk noise. The incoming signal from a distant radio has to be stronger and this is usually not the case. Let us all know how you go.Gotta have red sand on those boots !
AnswerID: 27433

Reply By: stillthinkinaboutit - Monday, Aug 11, 2003 at 18:20

Monday, Aug 11, 2003 at 18:20
Not sure where you have your antenna mounted, but if it is on the bull bar it is worth checking that the bar is in fact earthed.
On my GU Patrol the bar is bolted to the chassis rails but there are no earth straps from anywhere on the chassis to the engine block, battery or bodywork.
The only earth is through the fuel guage sender unit and the body mounts.
You may need to add an earth strap from the bar to the engine block or chassis.

Regards, Mark
AnswerID: 27472

Reply By: Eric - Monday, Aug 11, 2003 at 22:25

Monday, Aug 11, 2003 at 22:25
Parso.
THe noise can be from the antena or the alternator, to find out place a spare battery on the floor of the car and run the radio of that if the niose goes away run the positive lead directly to the battery terminal preferably runing the wire well away from the alternator. if the niose is still there redo your coax to the antenna also keep it well away from the alternator, consider running the coax under the mudgaurd to aviod the engine compartment. Eric.
AnswerID: 27525

Reply By: Sapper - Thursday, Aug 14, 2003 at 14:32

Thursday, Aug 14, 2003 at 14:32
Having fitted many an HF unit in the past we always ensured that everything was earthed including the chassis. Then in went the suppressors, to ensure that noise was minimal. This always worked. If you have a noisy HF unit you can always be assured that something somewhere on the vehicle is not earthed.
AnswerID: 27883

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