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Re: [RFI] Auto quieting

To: rfi@contesting.com
Subject: Re: [RFI] Auto quieting
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Thu, 8 Oct 2015 04:06:20 -0400
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Why not just use RG8 type coax for the 12 VDC wiring? I'd use separate cables for +/- instead of using the shield for the negative return. Color code the cables at each end with colored tape. Run the cables together. Use double shield for good measure. Yes they take up more space, but I've had good luck with it in the past. Use a relay to shut off the rig when the car is shut off. It does have drawbacks, but at least you won't run the battery dead if you forget to turn the rig off.

Both our cars have computers, ABS brakes, and my wife's car is a hybrid with well over 100,000 miles on it. Other than following good practice we took no special precautions. All this RFI talk has me afraid to purchase a newer car as it's getting about time as the maintenance costs are rising on the old 4-Runner. I can't convince my wife we need something with a lot of HP, but my old TA with the Corvette engine saved my life several times, even if it did make the ultimate sacrifice the last time. OTOH, I drove more miles in a month back then than I do in a year now.

It's the thought of having to RFI proof a new car causing me to hold off. Still. I can try them out and listen before buying. If noisy, I'll pass.

One class X-10 CME direct hit and the cars will be RFI quiet!

73

Roger  (K8RI)


 On 10/5/2015 11:51 AM, Michael Coslo wrote:
I used  old RG8 Coax shield - removed from the coax of course. Solder lugs on each 
end, and some heat shrink to keep it pretty. That will probably help with 
Kurt’s wire fraying issue too.

One odd thing, K0BG discounts the idea of much RFI coming from injectors.  Good 
site though.

I’m going to look at putting some coax shield over the injector wires, and 
ground at both ends. Maybe that will help my problem.


-73 de Mike N3LI -

On Oct 5, 2015, at 1:16 AM, Mike Ryan <mryan001@tampabay.rr.com> wrote:

I would suggest you taking a look at K0BG's website. He has about everything 
you could ask for with respect to mobile ops, from the types of car battery, to 
mobile antennas, grounding and bonding, etc.  It is a fantastic website with 
years of experience noted there. In my case I use inch wide tinned copper strap 
which cut to lengths as required. I think you would find the flat strap 
superior to round wire due to the additional surface area they provide.  - Mike

-----Original Message----- From: KD7JYK DM09
Sent: Sunday, October 04, 2015 11:53 PM
To: rfi@contesting.com
Subject: Re: [RFI] Auto quieting

"I had noise generated by the disc brakes on my car. When the static level
builds up (frequently) I step on the brakes and it cuts off like a switch.
It does not immediately come back but soon does."

I had this problem with static generated by the tires on the road arcing
over to the drive-line components.

I had another problem with massive static charges on a vehicle, I've been
thinking of the static wicks used on air-craft should this happen again.

Regarding bonding, which is better, flat woven strap or round cable/wire?  I
see everyone mention flat straps, but why?  I used them on a Toyota Celica
where I operated 6m/2m440 MHz, worked fine.  I sold the car to the OM up the
street, he came by one day, popped the hood and I noticed all the flat
straps had shattered in various places due to vehicle vibration.  Every
single strap was broken, wire pieces were all over the engine and components
and the straps were like cactus.

I've been eyeballing the various high-current ultra-flexible silicone and
XLPE covered welding wires at a local shop, they also have dozens of copper
connections in various shapes and sizes, thinking of using these when the
time comes.

Kurt

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