HF mobiile noise

[vk6hgr]

Hi Folks.

I've finally got around to putting my FT-857 in my Suzuki. The problem I have is that the car's fuel pump creates an incredible amount of hash noise on HF. I've put ferrite beads on everything and made sure everything is bonded but not much helps. Any ideas?

I made a short video demoing the problem here: https://www.youtube.com/watch?v=pxCRVyN5HR8

[VK6ZMS]

Have you tried turning the noise blanker level up from the default setting ?

Also does the noise appear when the antenna is unplugged ?

Is your antenna at the front or the rear of the car ?

Is the radio's case grounded straight to the car body.

Cheers

[vk6hgr]

ATAS-120 mounted st the front. Hmm. I now have some other things to check

[Nick]

0.1uf cap across the fuel pump.
Nick

[vk6hgr]

Did some more testing tonight... it is absolutely the fuel pump.

Disconnected the fuel pump relay and while the car keeps running there is only a tiny amount of impulse noise left which the noise blanker could take care of.

With some great calisthenics I managed to clip a ferrite bead across the fuel pump power cable (fuel pump is inside the fuel tank) but it made no difference. To put a cap across I'm going to have to get a mechanic to drop the fuel tank for me so it's a last resort.

[Nick]

Put it as close to the tank as possible.
Nick

[vk6hgr]

Put it as close to the tank as possible.

Hi Nick.

Any hints how I can do this without letting out the petrol tank explodium?

Any commercial kits out there? If I just do it homebrew with a capacitor in-line I'm worried it's not going to last.

[vk6hgr]

This guy seems to have the right idea

http://97vette.com/sporttrac/rfi_fix/rfi_fix.html

[Nick]

http://www.jaycar.com.au/productView.asp?ID=AA3060

I would try fitting this first to the +tive line to the pump and grounding the bracket.
Nick

[vk6hgr]

http://www.jaycar.com.au/productView.asp?ID=AA3060

I would try fitting this first to the +tive line to the pump and grounding the bracket.
Nick

Thanks Nick. I forgot about those!

[vk6hgr]

Still no joy.

I put a capacitor across and I even made a cable of ferrite beads like in that article... nothing I did made any difference.

I can only conclude that the noise is actually coming from inside the motor, and all the supression on the cables isn't going to change anything because that's not how the signal is radiating.

[VK6ZMS]

How did the no antenna test go ?

If its still there sans antenna a DC noise filter from a car Hi-Fi shop may help.

One worked a treat on my old VT Commodore.

[vk6hgr]

If I put a short antenna on the back of the radio directly it still picks up the noise, albiet weaker.

I used a DC power filter, the kind you use to get rid of alternator whine, and still no joy.

This has been the hardest noise problem I've ever tackled! I'm out of ideas. I need to get the fuel tank off. Ugh.