Old coil assembly from what?

[Terry295]

Can anyone please identify what this coil assembly may have come from ? Clearly a piece of RAF equipment, the switch is eight position, all coils are a single winding with a switched tapping.

The coils have part number labels 10C/4295 to 10C/4302 and 10C/4459. I suspect it is part of an oscillator section of a transmitter or signal generator, but that's just a guess. Thank you for any help.

Cheers TC

[HamishBoxer]

I too think possibly a signal generator.

[Silicon]

Pre-selectors, Wave-meters, filters, RF bridges and many more items of test equipment use coils.

[Radio Wrangler]

Judging the inductance values by eye, it's going to have appreciably more range than transmitters were normally made to cover, also there is little attempt to keep the low inductance coils mechanically stable to avoid drift especially at the high frequency end where it is more critical.

Receivers of that era usually have several tuned stages in their RF sections, and there are no ganged sections here.

With receivers and transmitters out of the spotlight, we have signal generators and wavemeters. It doesn't have the quality of mechanical engineering associated with particularly good ones but a good many were made to this sort of standard.

It could be a preselector to improve a receiver, but they came a bit later. Most receivers of the day tried to do as much as they could internally. External ones could have been single stage, but multistage is really needed to make a difference.

The RAF stuck their part numbers inside operational radio gear, but I'm not sure they were so punctilious about test equipment.

There is still an amount of mystery remaining....

David

[HamishBoxer]

Until proved otherwise,I will stick with signal generator.Certainly test gear.

[trh01uk]

I can't tell you what the whole assembly is from but here is the info I can find in AP1086:

10C/4302: Type 311 9.3 - 21.5Mc/s. No. of turns 9, 18 enam D.S.C. Moulded former X 262

10C/4459: Type 374 46 turns, 24 enamelled copper wire.

10C/4259 is not included in my copy of AP1086, which is not dated but includes amendments up to A.L.38.

Richard

[Terry295]

Thank you gentlemen for your replies. I had hoped that someone would have been able to identify a specific piece of equipment that it came from but it looks quite old and I was probably being unrealistic.

I am reluctant to scrap it for parts so I guess I hang onto it in the hope one day someone will need it for a restoration job, Thanks again

Cheers TC

[Julesomega]

I love that saddle support in pics 2&3, what equipments used that sort of phenolic moulding?

[Al (astral highway)]

Originally Posted by Terry295

I am reluctant to scrap it for parts so I guess I hang onto it in the hope one day someone will need it for a restoration job...

I'm adding to the votes for a signal generator - there's such a wide range of inductances there.

How about adding an oscillator, either valve or transistor, and making one?

[trh01uk]

The chances of identifying - let alone finding - the exact instrument that used this assembly is near zero. What most enthusiasts for military kit don't appreciate is what a truly, mind-boggingly vast range of equipment was designed and produced, particularly from WWII onwards - purely for military purposes.

Most military collectors focus (in the UK) on british army equipments, mostly 2-way radio equipment. Some think there are rather a lot of units called "Wireless Set No.xx" where xx ranges from 1 to 88! And many of the sets with numbers in between 1 and 88 exist - or did exist at one time. That's really a drop in the ocean when Royal Navy kit and in particularly RAF kit is added in.

You begin to get a flavour of the range of RN gear, when you look at just the receivers page on the Collingwood naval museum's page. Most of the receivers described are unknown, with most people being only aware of the "famous few", the CR100/150/300 series, and the B40/B41. Add in transmitters, and now we are getting really obscure. Move over into radar, and now we are into a mythical land ("There be monsters"!), of which only a few professionals who served with the kit have anything close to awareness, let alone familiarity.

However, its only when you venture into the field of RAF kit, and you first encounter some of the lists of equipment they produced and used, does the truly vast scale of "military electronics", unleashed in WWII, dawn on you.

There is no equivalent of the Collingwood site for RAF equipment, but our very own GMB's website starts to give a flavour. The page to look at is GMB's list of "Air Ministry Equipment Numbers". And then the corresponding page of "Aircraft Radio Installations" - with the realisation that ARIs were only one type of "installation" that the RAF had - there were

TGRI - Transportable ground radio installation
ATGRI - Air transportable ground radio installation
FGRI - Fixed ground radio installation
MGRI - Mobile ground radio installation

It can be instructive to take a look at AP116A, which is an index of RAF equipments and installations. If you turn to "Appendix R2", which is a simple list of radio installations, this runs to some 14 sides - and that leaves out some of the earliers ones that had become obsolete by 1960.

If we take just one radio installation - a well known one like H2S Mk.II ARI.5153 - and drill down into it, using GMBs list - he gives some 15 individual units that make up this system. When I say "units" - I don't mean small "accessories", like headphone, connectors etc. I mean large chunks of electronics with the complexity of a TV set, or an AR-88 receiver. Here's just one unit from H2S - the Indicator:





If you got all the H2S units together - then that one system would be bigger than some modest radio collections!

So to return to the original question. To answer it would require either

a) someone happens to have the unit with that assembly in it, and they recognise it.

b) we turn up a "Where Used" list produced by the RAF. I suspect the RAF had one, but if so, its been totally lost - probably buried in some very large hole in the ground!


Richard