[Milsurplus] Coaxial Cable of Mystery: Any ID?

Wed, 21 May 2003 17:43:43 -0700

The formula is:  138 log(D/d) for impedance.

Where:  D = inside diameter of the outer conductor (shield)
	d = Outside diameter of the center conductor
	The logarithm is the common log (base 10)

This will give you the cable's impedance, assuming no dielectric insulation,
such as Teflon, polyethylene, etc.
73,

Dick
W1NMZ

Glenn Little WB4UIV wrote:
> 
> Bruce
> 
> You can calculate the impedance of the cable. The formula is in the
> handbook. It requires two measurements, the inside diameter of the outer
> conductor and the outside diameter of the inner conductor. I do not have my
> handbook at the computer or I would list the formula.
> 
> The type of dielectric determines the velocity factor and the loss.
> 
> TFE cable is always lossier than PVC cable, but it has a higher breakdown
> voltage.
> 
> QED
> 
> 73
> Glenn
> WB4UIV
> 
> At 05:18 PM 05/21/03 -0700, Bruce Lane wrote:
> >Fellow listmembers,
> >
> >         I have here a large roll of nice Teflon-jacketed/Teflon
> > dielectric coaxial cable. It's double-braid shielded, about the diameter
> > of RG-8/U (maybe just a hair smaller), and it bears this mysterious
> > imprint repeating along a yellow marker tape for its entire length.
> >
> >         "B W65 OJ 12814"
> >
> >         This particular cable is, to the best of my knowledge, used on
> > aircraft transponders. I'm able to say this because it was a refugee roll
> > from Boeing Surplus, and I've seen the exact same stuff used for antenna
> > lead to the transponder space in the avionics rack.
> >
> >         HOWEVER -- Before I put it to use, I'd like to know if anyone can
> > tell me what impedance it is. I'm -really- hoping for 50 ohm nominal... ;-)
> >
> >         Anyone know for sure what this stuff is?
> >
> >         Thanks much.
> >
> >
> >-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> >Bruce Lane, Owner & Head Hardware Heavy,
> >Blue Feather Technologies -- http://www.bluefeathertech.com
> >ARS KC7GR (Formerly WD6EOS) since 12-77 -- [email protected]
> >"I'll get a life when someone demonstrates that it would be superior
> >to what I have now..." (Taki Kogoma, aka Gym Z. Quirk)
> >
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