On Wed, 5 Apr 2006 21:09:10 +0100, "Reg Edwards"
wrote:

I should like to know the velocity factors which occur on various
twin-balanced transmission lines. We have -

Some of these are included in my line loss calculator at
http://www.vk1od.net/tl/tllce.php and are displayed along with
calculated results. See below...


Open wire lines with infrequently spaced, flimsey spacers.

450-ohm ladder lines of various sorts.

Wes' measurements of Wireman lines are shown as Wireman 551 .. 554.


300-ohm lines spaced with a thin continuous web.

I have measured TV ribbon of this type with a 7.5mm conductor spacing
and IIRC was around 82%. Similar line with puched out peices was
around 87% from memory. I you need, I can measure the punched type, I
am not sure if I have the plain ribbon around.


130-ohm lines with two insulated wires stuck close together like twin
speaker cable.

See ZIP 105 for K8ZOA's measurements of US Zip cord. See Australian
twin flex for my measurements of Oz figure 8 flex.


75-ohm lines embedded in a solid eliptical-shaped polythene.

See Belden 8210 and 8222 (from Belden specs).


I daresay some of you have made measurements at one time or another.
The more data received the better. I can then take averages.

I can see someone wanting to by 10m of "average cable"... but I think
I know what you mean!

Hope this helps.

Owen
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