wowbagger's Journal: S9+20dB

S9+20dB - those of you in the hobby know that's either very good, or very bad.

In this case, it's very bad.

Since Christmas, I've bought an IC-7000, and strung up a longwire on an IC-AT4 from my tower, and it works very well, thank you.

Hamvention was last week, and I went, and bought a Mini-Tarheel screwdriver antenna, and a controller for it. I had hoped to do some HF on the drive back from Dayton. No such luck - I didn't get a good ground from the antenna to the trunk lid to the frame. "Oh well, an easily corrected problem when I get home" I thought.

So, some nice half-inch ground braid, some lugs drilled into the car, and that problem was solved.

Only to run into the next problem - S9+20dB of ignition noise. And of course, ignition noise is a pretty fair approximation of a series of Dirac impulses, so it clobbers most frequencies.

So I bought a bunch of split-core ferrites, and put two of them on each injector lead and each coil-on-plug assembly wire. I was hoping for 10 dB, dreaming of 30 dB of noise attenuation.

I got 0 dB. No reduction at all, at least as far as my radio's S meter indicates.

Now, the IC7000 has a pretty damn good impulse noise blanker - one of the advantages of being a software defined radio. But still, if you have too strong a signal coming into the ADC, there is no signal processing magic that will pull out a signal below the quantization noise + decimation gain. I know - I do this for a living.

So, I guess the upshot of it all is that my mobile HF work will be limited, and if I want to get serious, I had better pull over and shut down the engine. Which from a safety perspective isn't such a bad idea, I guess. (And no, I am NOT planning on operating anything other than voice while driving - I know there are folks who do CW driving. There are folks who watch TV while they drive, or read books, too - and I don't do that either.)

besides...

[RevMike]

If you were overheard saying "I enjoyed some Charlie Whiskey on the ride over," you'd probably be arrested for suspicion of DWI.

deisel

[zogger]

If this is your living and a serious hobby, wouldn't it be better to start with a vehicle that wasn't as noisy, say a diesel? A lot of decent diesels out there now, and obviously no ignition noise

cart/horse deal

Injector noise

[wowbagger]

You still have the noise from the injectors firing, if the injectors are electrically controlled.

Besides, I'm more of a sedan man than truck man, and there are very few sedans with desiel engines.

Re:Injector noise

[zogger]

is it as high as the 20 to 40,000 volts or whatever higher (up to 60 thou I think in some cases) that ignition systems use? I don't know really, but I would bet the typical gasser with electronic ignition is much higher in the RF noise area.

yes, fewer choices in the sedan area, but still some spiffy models at different sizes and price ranges, and with the price of fuel and mileage concerns and engine longevity etc thrown into the mix I think it is reasonable to at least consider it.

If you want to run this q

Ferrites

[srhuston]

You mentioned putting split ferrite beads on the cables, but were they the right material? I don't remember the calculation right now, but there's a calculation that can be done to figure out how many mH you need to attenuate the signal at a given frequency. You might find that different beads do a better job than the ones you've got. You also didn't mention which bands it blankets; 40? 20? 10? Yes? :>

Or, it could be a case where pulling over for a QSO is the best bet. There's probably some way of g

Some things to try

[pyser]

Sounds like the antenna end apparently is well grounded, but keep in mind though that a 1/2 inch braid can still be inductive enough as to not allow a good "ground" at RF frequencies. Newer cars are built with resistive plugs and plug wires, but if that's something that was overlooked, the plugs and wires should be changed. Shielded plug wires are sometimes needed.

You may have tried some of these already, but a few ideas come to mind:

- Is the radio itself well-grounded? How about the DC power -- i

Re:Some things to try

[wowbagger]

Power is clean - I have a second battery in the trunk just for these sorts of things, connected to the alternator by a battery isolator. I have also run the radio directly from a battery connected to nothing but the radio.

The car uses coil on plug - so there really aren't "wires" for the plugs, just the COP assembly on the plug. I have been thinking of trying to bond a ground from the COP to the engine - I think the return for the plug current is through the low voltage wiring side, which would be a hell of

Re:Some things to try

[pyser]

Sounds like you've done everything right from your end. If you haven't done so, try contacting the manufacturer of the vehicle. Most of the auto companies will help with RFI problems if you can locate the right people within the company. Start with the customer relations department and see where that leads you. Good luck!