[UK-CONTEST] Coaxial Connectors

[Giles Herbert]

Ray,
C types can be bayonet or screwed.  The "C" defines the insulator  and conductor shape in the mating halves and is applicable to both mechanical arrangements for latching them.  
I too used these in the BBC on IF cables on analogue Microwave links.  In this case they were the screwed variety.  The disadvantage of these was discovered in the winter when a cable needed to be used to monitor the IF on a mobile link on the roof of a frosty vehicle or on top of an icy domed top to a water tower!  Ice in the fine threads made for inventive swearing and chilly fingers!

Giles Herbert
G0NXA



> From: g3hrh at btinternet.com
> To: uk-contest at contesting.com
> Date: Sat, 4 Feb 2012 12:40:27 +0000
> Subject: [UK-CONTEST] Coaxial Connectors
> 
> 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 
> 
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