[TowerTalk] RG-58 capacitor

[Jim Brown]

On Sun,6/25/2017 9:19 PM, jimlux wrote:
> So, moral of the story is, check for the brand of your coax, and use 
> the appropriate length. 

And be even more specific -- although RG-numbers originally defined many 
specifications for cables, that has not been true for many decades. For 
example, there are hundreds of cables CALLED RG8, all different from 
each other in a variety of ways, and each carrying a different part number.

The only good place to look for cable characteristics and specs is the 
technical data sheet for the actual manufacturer of the specific cable 
type. AND -- only the major cable companies publish this data for their 
cables, and the data is as trustworthy as the mfr is.

As K1TTT noted, if the cable for your capacitor is a significant 
fraction of a wavelength, you'll have to analyze (compute) it as a stub. 
1/20 wavelength (taking VF into account) is a good rule of thumb for 
when the calculation is more complex than pF/ft multiplied by feet.

And, of course, if the capacitor is in a circuit carrying high power, 
you'll need to compute things like voltage breakdown and loss. And 
you'll need a decent data sheet for that too. :)

73, Jim K9YC