Electrical injector noise on HF radio help required

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goldypurple

Active Member
Posts
206
Location
Weeting, Norfolk
Guys,

I need some help, ive a land rover 90 td5 1999, and i run ham radio equipment and on my hf radio which is a kenwood ts480sat, i get noise on the frequencies.

The noise only appears when you use the accelerator which leads me to think its injector noise, the strength of it is around signal 3 and you sit staitinary with engine running i get no noise at all.

does anyone have any ideas how to cure this issue and get rid of the noise?

thanks
Andy
 
Do you get the same if you rev your engine whilst stationary?

You should have RF suppression in your lecky system, if not, you could fit an external suppressor to your power supply for the radio.
 
yes get the same noise when i rev the engine it goes from S0 to around S3 signal, do you recommend a suppressor? its quiet a high end and expensive item and am quite wary what i put in line.

thanks
 
As Oldsea suggested you should get a quality suppression kit. I am a Ham too and will be installing radio gear in my Landy at some point, I just got it. I will hook OP an oscilloscope on my 200tdi ele system to see how much noise I find and the frequency of it.
 
i have looked into this a bit more today, the noise isnt being picked up through the wireing of the transceiver, as the radio is all quiet with no antenna connected, when you attached an antenna then it picks it up so it being radiated somewhere.

i believe it to be from the injector as it increases and decreases with throttle responce, there are already ferrites on the power cable to the transceiver.

never had any issues with the radio in a 200 tdi or 300 tdi, the TD5 has more electronics :-(

at the moment im using am-pro whips for whatever bands i wanna use, in the process of installing a High sierra screwdriver type antenna also.

thanks
Andy
M0NKR ham call sign
 
I would have thought that the only thing that might generate RF interference would be the alternator ...

Is this across all frequencies or is it restricted to a single band/side band?
 
Last edited:
goldypurple said:
i have looked into this a bit more today, the noise isnt being picked up through the wireing of the transceiver, as the radio is all quiet with no antenna connected, when you attached an antenna then it picks it up so it being radiated somewhere.

i believe it to be from the injector as it increases and decreases with throttle responce, there are already ferrites on the power cable to the transceiver.

never had any issues with the radio in a 200 tdi or 300 tdi, the TD5 has more electronics :-(

at the moment im using am-pro whips for whatever bands i wanna use, in the process of installing a High sierra screwdriver type antenna also.

thanks
Andy
M0NKR ham call sign
Click to expand...

The body has to work as the ground radial, is this not the case? Did you check to see if you have a good antenna ground?
 
99.9% sure that'll be injector QRM, get up into 3rd or 4th, leave it in gear and take your foot off the gas, the interference will stop. Dip the clutch and when the revs bottom out the interference will start again.

As far as I know there's no absolute cure for it due to the inaccessibility of the injectors and as you've noticed it's radiating directly from the injectors and the cabling. Best bonding and earthing practises will help to reduce it so extra straps on the bonnet, the wings and the exhaust.

Get the HF antenna as far back as possible. Mines at the far rear through the roof, narrow IF filtering and the NB help to reduce the effect quite a bit if you're on SSB. Ignition Notes on RFI may offer some more advise on shielding.
 
Was about to say what Fanatic did - though i was thinking decoupling caps across the injectors. if you can get the clip-across ferrite beads that used to be used on electrical cords they mightbe worth a shot on the individual leads to the injestors as well.

I've seen that work in nooisy environments if not specifically on Diesel injectors.

ajr - WA1YHY
 
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