[TowerTalk] N connector, Re: UHF (PL259) soldered center

[jimlux]

On 6/26/18 7:18 AM, Jim Thomson wrote:
> 
> ##  Forget what amphenol  states.  A  teflon PL-259  will hi pot test a heck of a lot higher
> than a  Type N.   Type N uses a puny center pin, identical to a BNC.

Actually not - .120" (N) vs 0.053" (BNC) - you're looking at that 
tapered guide pin, but that's not the current carrying part.


  The center pin
> on any PL-259 is huge by comparison.  There is no RF on the center pin any way. The
> RF travels down the outside of the mating female of the   SO-239. 

Uh.. Current in the center conductor is equal to the current in the 
shield. technically, current in the outer surface of the center 
conductor matches the current in the inner surface of the shield.

The current *density* is higher on the center conductor (since the 
conducting "layer" thickness is the same on both, and the center 
conductor is smaller than the shield - so the heating limit (which is 
one of the power limits for coax) is set by the inner conductor size and 
the thermal conductivity to the outside.

Maximum power handling is kind of a tricky thing - voltage breakdown 
usually isn't the limit unless the connector's insulating surface is 
dirty. Thermal limits are more the problem.  Think about it... the hot 
part of a coax connector or cable is the "inner conductor" which is 
surrounded by a nice thermal insulator like PTFE or foamed silica or 
foamed PTFE.