Nology

[Raymond C Drouillard]

On Tue, 29 Dec 1998 18:11:03 -0500 jsg at donet.com writes:
>
>
>| 	If Nology wires are not properly grounded, then you get get
"excessive
>| RFI". By proper grounding, I don't mean just bolting the ground straps
to
>| the most convienent point, but ensuring continuity as well. Was the
>| installation even checked for continuity to ground? For some cars,
Nology
>
>properly grounded with braids... RF shielding simple doesn't work
>that way. 
>
>| They were all grounded at a single point on the head, and resistance
from
>| the braids to anywhere on the block, frame etc, never exceeded 0.05
ohms
>| with a 4 lead sensing ohmmeter.
>| As an experiment after the PCM was replaced, I placed an oscilloscope
on
>| the power antenna lead from my stereo.  With the stock wires, I had a
clean
>
>You can not measure RF impedance at DC as you found out. A shorted
>transmission line 1/4 wavelength long will have an infinite
>impedance. If you didn't know that, you would be surprised at what one
>can do with a few ferrite cores and some coax. Also, keep in mind
>that a slot in a large sheet of metal is an excellent radiator (a
>complementary antenna). The techniques that you use to test (and
>ground) at DC have little to no value at RF frequencies.

All so true... but do the manufactures give their customers any hints in
testing the RF impedance?  Do they specify a ground braid length?

What frequency are we talking about anyhow?  Spark transmitters tend to
transmit a very broad signal.  No matter what you choose, you are going
to filter out some frequency and pump the energy into others.

Of course, there is probablly a resonent frequency associated with the
wire.  It is, after all, an LC circuit.  Do the good conscientious folks
at Nology give their customers a clue about how to determine this and
adjust the length of the ground braid accordingly?

Or, perhaps the RFI is just something that happens in an unpredictable
fashion?  (randomly?  nah... chaos system)

Do they warn that it might happen even with a low DC resistance to
ground?  Do they warn their customers that they should test for RFI and
take steps to fix it if it occurs?  Do they offer help to those (perhaps
few) who have problems because of their wires?  Appearently not.

Even if RFI is only a problem in .01% of the installations that are done
to their specifications, they should have the integrity to do what it
takes to make things right with the unfortunate customer.  I like to do
business with people who have that kind of integrity.

Ray Drouillard, BSEE
KA8UUU

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