[Racal] Racal (and others): peculiar mains power connector question

[Robin Birch]

Hi,
I can't remember if the RA17 plug is a plessey connector but it is  very 
similar to one.  Essentially you can get many different inserts for 
these with lots of different pin arrangements.  The idea of the rotating 
inserts is so that similar plug / socket combinations will not get mixed 
up on a single piece of gear.

There is no right way of doing it, it is entirely down to the designer 
and each companies internal standards.

Robin

In message <5.1.0.14.2.20020129000656.00b0c2f8@mail>, PA3GYU 
<pa3gyu@amsat.org> writes
>Hi all,
>
>(Hope this makes sense to you, I am writing in a language foreign to my own.)
>
>I am confused. Let me explain.
>
>I own several boatanchors originating from the UK that have a three-pin 
>power connector, like the one on the Racal 17. Err, well - I ASSUME 
>every Racal 17 has this particular connector, so
>I am already at unfamiliar territory here....
>
>The gear I am referring to: a Racal 17, a Racal sideband convertor, a 
>Marconi signal generator and a Cossor scope. Maybe this is of some 
>relevance.
>
>The power connector I am talking about has three pins labeled A, B and 
>C - the first two of which are connected to the mains and the latter is 
>connected to earth. All four boatanchors use the same pin dedication - 
>no problem here.
>
>This pecular connector has notches on the outer ring, enabling it to be 
>connected in only one way to the socket. But the innards of the 
>connector can be rotated during assembly, allowing for several 
>different orientations. The socket on the chassis is made up the same 
>way.
>
>I would assume that there is one standard way to orientate the innards 
>of such a plug in the outer ring. Then any powercord would plug into 
>any equipment - easy.
>Apparently there isn't just one standard, as the connector for the 
>Marconi and the Cossor are interchangable, but fit neither the Racal 17 
>nor the Racal sideband convertor. And the plug on the Racal 17 isn't 
>identical to the one on the sideband convertor either!
>
>So I end up with four pieces of equipment and three different plug 
>orientations.
>
>So.... What is the story about this type of mains plug? Are they 
>supposed to be different?
>Anybody any ideas?
>
>Just curious, I can plug them in allright, but the question keeps 
>nagging at me ;-)
>
>
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