[UK-CONTEST] Coaxial Connectors

[Ray Hills]

Been following the discussion with interest. I agree that pressure sleeve 
connectors are preferred in all cases.  I use 259s on HF and  have had no 
problems with PS types.  Same goes for N-type.  Earlier PS versions do not 
trap the outer significantly well and can work loose in time.  The current 
version uses a "top hat" slid between braid and insulant and gives a much 
better mechanical joint.  The problem with soldered outer types is that by 
the time the solder has taken hold, the insulant has softened and can leave 
the pin off-centre and maybe even pulled out.  The only ones that seem to 
avoid that trap are those with PTFE insulant.

I also use RG213 cable for high voltage DC conections with PL259 
plugs/sockets.  Seems fine up to 2.5 kV with good quality connectors.  The 
cheapo's with "bakelite" insulators do flash over but PTFE ones are OK.  But 
even so do not rely on the outer as the sole DC return path.  A separate 
bonding earth between PSU and TX etc is an essential safety feature.

No one has mentioned C-type connectors.  When I was at the BBC (moons ago) 
we used them on all low power Band II and Band III equipments.  I built up 
quite a collection and use them here for 144 MHz (but N-type for 432).  They 
are a "bayonet" plug which with a quarter turn on the sprung outer ring 
locks over two studs on the socket.  Particularly useful on my patch panel 
which has a built-in Bird coupler element and requires a lot of lead 
changing between bands.  Much easier to use than N-type where I find the 
pitch of the outer thread so fine that cross-threading can occur unless very 
careful.  Maybe that is due to increasing clumsiness with age, of course?

Like the BNC the C-type comes in 50 and 75 ohm versions so check the pin 
diameter.

Ray G3HRH