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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 31st Jul 2022, 5:32 pm   #1
David Simpson
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Default Military Compass Repeater

Just acquired this 8" dia. compass display item from a silent key dispersal. The circular card has been changed from a 0 to 360 degree one to a nautical bearing one.
Stamped into the matt black faceplate is a crow's foot & 5T/238 below the needle spigot, and "DEPRESSION" (lhs) & "ELEVATION" (rhs) above. OS 2000 is stamped into the rear bakelite casing. Haven't got round to feeding an AC source into the T/F, will wait for expert advice. The 5 wire rear terminal plate looks similar to the connector on my ex military Desyn Test Set, but that takes 24V DC. As does the wee compass repeater shown in my Desyn thread - what - 3 or 4 years ago. Maybe a display for a motorised antenna, or perhaps the old chap was planning an RDF display to work with his (grotty looking) 1155 Rx. I've no idea.
Any advice most appreciated, please.

Regards, David
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Old 31st Jul 2022, 6:16 pm   #2
Dennis M
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Default Re: Military Compass Repeater

Looks similar to the selsyn transmitter and receiver set up I used on a home made aeriel rotator over 50 years ago.(I still have the transmitter and receiver in the garage loft).My pole sat on a Mini car brake hub and was driven by an old Creed teleprinter motor, top bracket had a surplus bearing sleeved down to fit the 2" pole.
If it is it should run on 400Hz, running it on 50Hz will not give accurate bearings on the display.
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Old 31st Jul 2022, 6:44 pm   #3
Ed_Dinning
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Default Re: Military Compass Repeater

Hi David, yes looks like a Selsyn type of device.In MIL guise they normally worked at 400Hz, but I believe some were designed for 50Hz, what does it say on the unit?

Ed
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Old 31st Jul 2022, 7:32 pm   #4
ex seismic
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Default Re: Military Compass Repeater

Depression and Elevation indicates gunnery origins.
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Old 31st Jul 2022, 8:07 pm   #5
jamesinnewcastl
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Default Re: Military Compass Repeater

Hi

This is a really good read on such devices!

https://reports.aerade.cranfield.ac....=1&isAllowed=y


Cheers
James
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Old 31st Jul 2022, 8:51 pm   #6
David Simpson
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Default Re: Military Compass Repeater

Thanks James for the link. 'Fraid Ed, nothing etched or printed anywhere relating to frequency, 400c/s or otherwise.
The T/F is made by The Douglas Coil Company, & the i/p primary tapping's are at 0 & 250V. Powered up on my Variac - & the secondary o/p measures 27.3V.
Hopefully some military ref. no. guru can identify the 5T/238 reference number ? Will put a thread post on the VMARS Forum site as well.

Regards, David
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Old 31st Jul 2022, 10:46 pm   #7
M0FYA Andy
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Default Re: Military Compass Repeater

I'm struggling to find any reference to Section 5T in the Air Ministry Stores Reference list, AP1086. The Index I have doesn't include Section 5T, so I don't even have a title.
However I have found the attached picture in my archive, 5T/237, obviously closely related, but with no further details.
Very puzzling!

Andy
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Old 1st Aug 2022, 1:08 am   #8
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Default Re: Military Compass Repeater

If it was an aircraft device, I would expect the transformer to be for 115v 400Hz, so a lot smaller than the iron you have. The only time at sea that I recall the 'course to steer' as a bearing on the bridge chalkboard was on a Geordie collier in the 60's, peculiar things like "NE by N 1/2 N" - on our RNVR Minesweeper it was definitely degrees. Interesting that it shows bearings rather than degrees and in a nice wooden box, I'm wondering if your synchro repeater was from a training school, the bearing scale looks hand printed.
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Old 1st Aug 2022, 11:12 am   #9
David Simpson
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Default Re: Military Compass Repeater

Hey Guys, that's identical, and certainly the varnished wooden case lends itself to a military classroom. Wish my memory was sharper - the NAV. Inst. training section was just next door to the practical workshops where I was an instructor, 50 years ago at RAF Cosford, & our duties sometimes crossed over.
When I acquired it on Saturday, not having un-screwed the back cover, I'd hoped it might compliment my Desyn testing set-up.
For maritime usage, maybe I'll put a post on the "Ship's Nostalgia" "Radio Room" Forum. Guys there have been jolly helpful over the years.
The deceased chap(late 80's) whose kit I acquired, hadn't been seriously active in amateur radio pursuits(he was a "G3") since the 70's. So perhaps this repeater was a shelved "to do" project. His only rig was a full KW2000/1000 set-up, (in great cosmetic condition, & now residing on the only spare space I now have - a woodworking bench, but well covered in a big dust sheet).There was no corresponding antenna DF kit with the KW stuff. It's now destined for a G8 VMARS local pal, who has been laid low with covid. However, I've acquired the old chap's IC-22, & its working great after all these years, with a magnetic whip plonked on my Yeti roof.

Regards, David
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Old 1st Aug 2022, 11:35 am   #10
M0FYA Andy
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Default Re: Military Compass Repeater

David,
Is there any chance of a picture showing the 5T/238 marking for my photo archive, please?

Many thanks,

Andy
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Old 2nd Aug 2022, 12:27 pm   #11
David Simpson
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Default Re: Military Compass Repeater

I'll try Andy, but don't be too hopeful. The markings are only faintly stamped into the matt-black face plate & I needed a bright circular bench-light plus a wee magnifying glass to read them. I'll maybe try a lead-pencil "rubbing".

Regards, David
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Old 2nd Aug 2022, 4:11 pm   #12
M0FYA Andy
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Default Re: Military Compass Repeater

OK, thanks for looking!
Andy
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Old 6th Aug 2022, 9:59 pm   #13
David Simpson
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Default Re: Military Compass Repeater

Well Andy, bit of trial & error, but this is the best I can do. I'm not actually needing the repeater, and shall ask around our wee gang up here if someone wants it. If they don't, then its yours backsheesh if you want it.

Regards, David
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Old 6th Aug 2022, 10:00 pm   #14
David Simpson
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Default Re: Military Compass Repeater

Forgot the picture
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Old 6th Aug 2022, 10:41 pm   #15
M0FYA Andy
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Default Re: Military Compass Repeater

David,
Many thanks for persevering!
I can't think of a use for the unit, so give priority to anyone who can use it, although I'll give it a home rather than you skip it!
Thanks again,
Andy
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Old 7th Aug 2022, 7:06 am   #16
G3VKM_Roger
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Default Re: Military Compass Repeater

Quote:
Originally Posted by ex seismic View Post
Depression and Elevation indicates gunnery origins.
That's a possibility, maybe the people who run the RAF Langham Dome might know more?

https://langhamdome.org/

Cheers

Roger
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Old 7th Aug 2022, 10:01 am   #17
David Simpson
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Default Re: Military Compass Repeater

Hey Roger, I guess I should be ashamed of not knowing what the RAF Langham Dome is. Having spent a total of 6 years at RAF Cosford, I ken all aboot their Museum. Have also been in touch with the Communications Museum at RAF Henlow, several times. But Langham ?
Don't worry Andy, there is no chance of me skipping the selsyn repeater.

Regards, David

PS. Just Googled it - By sheer coincidence, RAF Cosford was one of the other stations which had an identical Dome. It was situated between the A41 road junction & Cosford Halt and its railway bridge. Demolished in the late 60's.

Last edited by David Simpson; 7th Aug 2022 at 10:10 am. Reason: Additional info
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Old 7th Aug 2022, 10:52 am   #18
pmmunro
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Default Re: Military Compass Repeater

While elevation and depression would be strong indicators of gunnery applications, would it not have had to be in a training establishment?

A large glass fronted instrument in a plywood box would not have stood a chance of survival beside a gun which had to move rapidly and be laid in the vicinity of large heavy shells being handled with some considerable urgency! Even on a ship it would have been rather delicate.

The need for an electrical supply suggests that at least some motor vehicles must have been around when it was used, but more likely a building of some kind.

PMM
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