GPO/BPO 620 plug, 6 way
 

I've only come across this connector when it's been attached to a headset, for example, to connect to a radio, telephone and intercom console in an airport control tower or coastguard station, for example. Did Post Office Telephones ever use them in in their Plan installations, along the lines of the 420 and 520 ?

Thankyou.

Re: GPO/BPO 620 plug, 6 way
 

I have never come across the matching socket, though I have several of the plugs, so I too would be interested to know where they were used.

Apologies for being unable to provide any more information.

Re: GPO/BPO 620 plug, 6 way
 

I have a socket that would take that plug somewere, along with one of the plugs. It's a panel mounting thing, and I think there's a break contact on each position (so 12 solder tags on the bottom). RS sold them many years ago.

I don't remember seeing anything other than 4 pole and 5 pole plugs and sockets in the N diagrams, but I might have missed something.

Re: GPO/BPO 620 plug, 6 way
 

The socket is called a SO620, reasonably enough, and is like Tony describes. Totally different to its 4-pole counterpart.

Re: GPO/BPO 620 plug, 6 way
 

Unfortunately, when Iask Google about SO620, it just brings up lots of irrelevant hits - mostly about shower heads!

Re: GPO/BPO 620 plug, 6 way
 

I've attached a photo of my 6 pole plug and socket. The socket has 'RS' on the fixing bush (obviously not visible in the photo) so that's where it must have come from.

I have also got the November 1992-Februrary 1993 RS catalogue to hand. It lists the following 'BT Type Jack Connectors' :

4 way plug (BT 420) 478-677
4 way socket (BT 84A) 478-683
6 way plug (BT 620) 478-712
6 way socket (-) 478-728

It's interesting that the socket has no BT reference number given (although the plug does).

Re: GPO/BPO 620 plug, 6 way
 

I think the 420 and its jack are still made by Astralux or someone or other. The 620 was made by Rendar then Schurter but I think it's now out of production. Goodness knows if there is any modern call for them among the likes of Lemo, Fischer et al.

Re: GPO/BPO 620 plug, 6 way
 

Just found one of these when I was looking for my Tele 713 (other post). It has a two-core mains lead attached with just the neutral / earth cores used and lugged at the other end. According to the heat-shrink sleeving, was used on an RAF 'D'-key. Ex-Kinloss or somewhere, I think.

Re: GPO/BPO 620 plug, 6 way
 

Thanks Russell. Now I'm wondering what an RAF D-key is !

Re: GPO/BPO 620 plug, 6 way
 

It's a Morse key.

Re: GPO/BPO 620 plug, 6 way
 

Thanks Bill.

Re: GPO/BPO 620 plug, 6 way
 

Just remembered, I've seen an SO620 socket on the front panel of a Plessey Watchman radar data processing unit. Nothing plugged into it though, so no idea what it's for.