Diesel Jackaroo and HF Interference

Submitted: Sunday, Jul 06, 2003 at 10:14
ThreadID: 5835 Views:1816 Replies:4 FollowUps:1
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This question has been asked before, however solutions have been offered for the car radio fitted. Has any one found a solution for cutting down the engine interefence to enable tthe use of HF whilst the engine is running.
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Reply By: Tuco69 - Sunday, Jul 06, 2003 at 10:27

Sunday, Jul 06, 2003 at 10:27
First you need to advise what type of noise yau are having problems with.

Does the noise change with engine revs?
AnswerID: 24306

Reply By: Mixo - Sunday, Jul 06, 2003 at 10:56

Sunday, Jul 06, 2003 at 10:56
I've been doing battle with this for 3 years (and failed). I know of an EFI petrol Jack owner who has the very same problem and does not monitor whilst mobile....too much racket. A very sad situation in my view. But the Jack is a world car and the designers probably care little about HF, even though the car radio is ultra low HF and CB's and long distance HF have been in cars for years.
Goes to show how much they care about prospective client needs. My guru says it is the diesel injector circuit, its powerful and you won't beat it (you won't hear it when throttling off). Problem is the HF and its ability to "pick up" the weakest of signals.
I would be very interested to find someone who could conduct a fresh investigation. There probably IS a way to beat it, but technical expertise would be required.Gotta have red sand on those boots !
AnswerID: 24308

Follow Up By: Mixo - Sunday, Jul 06, 2003 at 11:01

Sunday, Jul 06, 2003 at 11:01
Forgot to say....there is apparently a gizmo in the Barret 950 that could be tweaked to cut out the specific frequency of the injector noise (when running they just get faster/slower, but stay the same re frequency it seems). I have not pursued that, because I assume that I would lose parts of any incoming modulated transmissions that cross that frequency. I'm no technician - just an assumption. The Codans and others may be able to be tweaked too.Gotta have red sand on those boots !
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FollowupID: 16364

Reply By: Eric - Sunday, Jul 06, 2003 at 22:23

Sunday, Jul 06, 2003 at 22:23
CHrisp.
In military vehicles used for radio coms the injector leads are run in coax and the soleniods have metal cans over them, in the jack you would have to make a metal box for the computor as well. A lot of work but if your determined you will get there.
Eric.
AnswerID: 24366

Reply By: Tuco69 - Monday, Jul 07, 2003 at 08:01

Monday, Jul 07, 2003 at 08:01
Crisp - in the years that I've had communication radios in my vehicles (27 MHz CB, HF RFDS radio, and UHF CB) it seems that any interference comes into the radio either via the antena or the 12V supply.

I've overcome the problem in our present vehicle by moving the location of the autotune antena from the bullbar to the rear mounted spare wheel bracket. This distances the antena futher away from the source of the noise - alternator or ECU. Also this means that the antena coax and also data cable to the antena are not run through the underbonet area. Our present vehicle is a Toyota Surf - 1KZ-TE diesel. It has an electronic fuel injection pump controlled by the ECU. Our radio is a Barrett HF550R with autotune antena.

We are all told to wire our 12V supply direct to the battery. This will ensure maximum voltage is available for the radio. This situation can be improved by only wiring the POSITIVE direct to the battery, and cutting the negative (earth) lead as short as possible - fixing it to a GOOD earth point close to the radio. By using the body to carry the earth a slight voltage gain will be achieved as well as eliminating the chance of interference entering the radio via the long negative (earth) to the battery. Most good radios are usually well filtered at the radio - but usually only on the positive (+12V) supply.
Even our Electrophone TX4200 UHF was suffering interference (alternator whine) prior to me shortening the earth lead.

Determing the poin of entry to the radio is relatively easy - simply disconnect the coax at the radio while the engine is running. If the noise stops, then the interference is via the antena. Relocating the antena and ensuring that it is well earthed and fed with good quality coax (not damaged) is a good start.
AnswerID: 24377

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