Radio Junction Box Type 31 B/A

Hello Andy,

Thanks for the additional info and the time taken with the search. As noted above Fig 3 Radio Installation AP info attached below.

Tim

[ATTACH=CONFIG]251045[/ATTACH]

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Tim,
Another ‘near miss’, these are the types of this Junction Box listed in a copy of Section 10A I have, but no Type 31 unfortunately.

I have a later version where the list has reduced to only Type 1 and Type 17.

Maybe Hendon Museum have a copy with the right Amendment List? I suspect these boxes bespoke to a particular aircraft type didn’t last long.

Andy

Hello Andy,

Many thanks for your comprehensive reply it really is appreciated. I do indeed have Fig 3 so will re-size and upload for your information. Whilst I appreciate that TR1133 components are very hard to come by it is the radio installation I am trying to re-create within my Miles Martinet project. I am by no means an expert on these installations, hence the request and how welcome your reply has been.

Will add further info shortly but just wanted to say thanks.

Kind regards,

Tim

OK, Tim, I think I’ve got very close to answering your question! As I said earlier, what is needed is a later issue of A.P.1186 than I have, to cover the later variants of the TR1133.

Picture 1 shows the equivalent drawing of the TR1143 installation.

The others show what I’m sure is physically the same as your JB31, and may well be identical internally. Clearly each aircraft type required a bespoke JB with cable lengths to suit. I guess it saved a bit of weight compared to the JB17 with connectors, but it seems a very odd way to go about things!

What exactly are you doing, are you trying to recreate this installation? TR1133s are very thin on the ground, I imagine the JB Type 31 will be impossible to find, so you’ll have to make one…….

I hope this is helpful.

Andy

As a further snippet, the TR1143 diagram shows a 18-pin connection from the JB 17 to the A1271 Beam Approach amplifier. I’ll wager that is equivalent to the stowed connector on your diagram, and B/A does indeed mean Beam Approach. Thie fact that the connector is stowed does support the idea that the JB 31 has flying leads.
Andy

Hi Tim,
What an interesting picture, very many thanks for that.
For starters, the JB Type 51 was a complete red-herring, forget that. But I am intrigued by the B/A reference above………….
I can find information on the TR1133 (but not F or H) in my copy of A.P.1186, but no mention of a JB.
However, the whole system architecture is very similar to the TR1143 which replaced it, and uses a JB Type 17 in a very similar role.
It looks to me from your diagram that the three cables going into each dide of the JB go in through cable glands rather than connectors, as they are shown to be quite small and aren’t identified with connector types. Do you agree? The JB Type 17 uses W-connectors on each side. It does beg the question how they are terminated – I can’t see there being room for terminal blocks, so I womder if the cables came as part of the JB? The stowed 18-pin connector is interesting, do you have Fig 3?
Probably what is needed is a copy of A.P.1186 at the right issue, has anyone got one?
I’ll extract the equivalent diagram showing the TR1143 wiring, it must in the limit be feasible to work out what is in JB 31 as it clearly does the same job as the JB 17.

Andy

Andy Y,

Many thanks for the reply and apologies for the lack of context. I have the JB Type 31 as forming part of the Martinets TR1133 radio installation as detailed on the attached AP page.

Regards,

Tim

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A further thought, are you sure you mean JB Type 31, and not JB Type 51? The latter is part of Beam Approach, is that what B/A in your question refers to? If so, it’s covered in A.P.2534B.

Otherwise it might help us to look in the right place if you explain the background to your question.

Andy

Do you by any chance have a picture of one? I can’t find any reference to it.

Andy