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Old April 5th 06, 09:57 PM posted to rec.radio.amateur.antenna,rec.radio.amateur.homebrew
Ronnie
 
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Default Question about auto antenna cable and connectors

Roy is right. I looked up RG62 and this is not the cable I have.
Here's what the autopilot service manual has to say about this
cable.

"The coaxial harness assembly CD-1, 2 and 3 is manufacued to specific
lenghts and since the cable is a part of the tuned circuit, these lengths
must
not be altered. The sensor leads are made of very fine wires that are fed
through a hollow insulator. Note that the fine wire has been coiled to
provide flexibility and reduce the possibility of beaking and causing an
open in the circuit."

The diagram shows a hollow tube with a fine wire that is coiled running
through it, a braid style shield over the hollow tube and an outer jacket
over the braid. It seems to be a variant of the auto coax where the fine
wire center conductor has been coiled instead of being left straight.

Thanks for all the help with this, but don't worry yourselves about it.
I have all the orginal pieces with connectors intact, but I was hoping
to find the technical specs on the cable so I could understand the
cable's impact on the resonant frequency.

Ronnie

"Roy Lewallen" wrote in message
...
Michael A. Terrell wrote:
. . .
One of the engineers at Delco told me it was RG-62, and 93 ohms when
I was going to their annual car radio training back in the early '70s.
IBM also used RG-62 on their coaxial computer networking, but they used
BNC connectors.


The automotive coax I'm familiar with isn't RG-62.

Like automotive coax, RG-62 has a thin walled hollow insulating tube. But
RG-62 has a polyethylene "string" which is helically wound around the
center conductor to keep it centered in the hollow tube. The coax in every
old automotive installation I've seen lacks this PE "string", so the
center conductor is free to flop around inside the hollow tube. The effect
of the "string" is to make RG-62's Z0 constant and predictable, and it
will also increase the capacitance somewhat. Constant Z0 isn't important
for the automotive application, and low capacitance is important.

It seems to me the center conductor is smaller in the automotive coax than
in RG-62, also.

Roy Lewallen, W7EL