[TowerTalk] Cable on a reel using a formula?

[Gary Schafer]

Mark . wrote:
> Kieth wrote:
> 
> << Pi * r squared is area of a circle.  What you will need is 2 * pi * r, or 
> pi * diameter, which is circumference.  However, this is accurate only for 
> the turns on one radius.  You can get fairly close by counting the outer 
> turns across the reel, then estimate how many layers there are to the inner 
> layer, then adding all together.  Calculate circumference using r measured 
> from center of layers to center (axle) of reel, and multiply by total number 
> of turns...SNIP...73, Keith NM5G >>
> 
> Keith has got it, and this requires an iterative solution: estimate a 
> packing factor (for how neatly the coils nest), calculate the number of 
> layers, then the number of turns per layer,  and then calculate the cable 
> length for each layer, adding them up as you go.
> 
>   I wrote a handy 'hose length calculator' program to solve this problem 
> using BASIC in the late 80's. In planning the installation of a CCTV system, 

That is one way to do it. But as another poster relayed, finding the 
volume of the reel and the volume of the cable is a much easier way to 
do it. Then you don't care how many layers or turns are on the reel.

73
Gary  K4FMX