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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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10th Aug 2018, 11:55 am | #1 |
Pentode
Join Date: May 2011
Location: Enniskillen, Fermanagh, UK.
Posts: 188
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Is this a Rebecca unit ?
My friend says this is a Rebecca, so I do the usual internet search but I'm not getting close to radio equipment. Anybody know of a link to follow. thanks, Cliff.
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10th Aug 2018, 12:37 pm | #2 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
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Re: Is this a Rebecca unit ?
A picture of the whole unit would be useful.
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
10th Aug 2018, 2:55 pm | #3 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: Is this a Rebecca unit ?
I believe it is a Test Set associated with Rebecca, probably Rebecca Mk4.
If you ever decide to sell it I would be an willing customer, I am interested in any aircraft equipment including test sets! Andy |
10th Aug 2018, 6:04 pm | #4 |
Pentode
Join Date: Jun 2006
Location: North Hertfordshire, UK.
Posts: 179
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Re: Is this a Rebecca unit ?
This could start you off
http://www.duxfordradiosociety.org/e...reka-hist.html BTW Duxford is always on the look out for interesting pieces. TYJ
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11th Aug 2018, 1:38 pm | #5 |
Pentode
Join Date: May 2011
Location: Enniskillen, Fermanagh, UK.
Posts: 188
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Re: Is this a Rebecca unit ?
Thank you for the replies. More photo's here. Not sure it will be of much interest. Also I have asked the owner to measure and weigh it, so as to get a courier quote. Thanks, Cliff.
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11th Aug 2018, 2:02 pm | #6 |
Moderator
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Location: Ipswich, Suffolk, IP4, UK.
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Re: Is this a Rebecca unit ?
The mechanical enclosure looks similar to the Rebecca MKIV transponder on the IWM Duxford website linked to in post #4.
It is obviously an item of test equipment though and the name plate seems to confirm this.
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
12th Aug 2018, 8:58 am | #7 |
Hexode
Join Date: Apr 2017
Location: Buderim, Queensland, Australia.
Posts: 428
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Re: Is this a Rebecca unit ?
Here is the complementary Eureka equipment at Duxford 2017
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12th Aug 2018, 1:01 pm | #8 |
Hexode
Join Date: Aug 2010
Location: Malvern, Worcestershire, UK.
Posts: 347
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Re: Is this a Rebecca unit ?
Given the near identical case and use of US derived miniature valves this is spot on for REBECCA 2, also used aboard D day troop landing gliders, the PTFE valve holders of the McMurdo type fitted are just about the earliest implementation that I have seen, in more widespread use from 1947 on.
Of course, I stand ready to be corrected... Quick edit-had this not been test set equipment but instead the airborne TX,then it would have carried the HE demolition charges to be blown by crew/operator in the case of aircraft being downed to ensure that an enemy would be denied a working complete example in case they should use it to devise jamming countermeasures or copying as a whole. Last edited by VT FUSE; 12th Aug 2018 at 1:14 pm. |
12th Aug 2018, 2:01 pm | #9 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: Is this a Rebecca unit ?
I don't agree that this Test Set is for Rebecca Mk2, it is referenced in A.P.2914Y, A.R.I.5610, Rebecca Mk4.
Rebecca Mk2 uses the typical construction methods of WW2-era equipment, prior to the introduction of cylindrical sealed housings as used in the Rebecca Mk4 Transmitter/Receiver airborne unit. Why this Test Set also used a cylindrical housing I don't know, perhaps for commonality, but this was then housed in a rectangular framework/case, presumably to stop it rolling about on the test-bench! The A.P. for Rebecca Mk2 lists the applicable Test Equipment, I could extract the details if anyone is interested. The A.P. for Mk4 makes no mention of demolition charges, wartime experience showed that they were more trouble than they were worth in IFF, Gee and H2S units - to be big enough to successfully destroy the equipment would be big enough to bring the aircraft down, and inadvertent operation occurred far too frequently, so they were deleted before the end of the war. Andy |
12th Aug 2018, 2:11 pm | #10 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Is this a Rebecca unit ?
Who was the manufacturer?
Lawrence. |
12th Aug 2018, 8:45 pm | #11 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,396
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Re: Is this a Rebecca unit ?
Picture 3 in post 5 has answered a long-term puzzle- as a kid, I acquired a compact British-made IF strip, passed onto me by a military tech, and the upper left hand corner of that shot is exactly it- if so, it'll be 6x CV138 (EF91) VHF (45MHz?) amp stages folowed by CV140 (EB91) detector and CV136 (EL91) cathode follower "video" output to the adjacent coax cable. The round items between them with a small oval detail being the trimmer cores and the alternating triangular thingies each containing 3x 1nF "Metalmites"! Unfortunately, I dismantled it long, long ago. I suppose the post-war replacement/equivalent for the likes of the famous EF50-laden Pye strip.
One thing that I've always found slightly amusing/puzzling about quite a lot of older avionics kit in particular is that some aspects of it will be almost ludicrously overbuilt, with almost trifling weight savings made elsewhere and this is a good example- that hefty great enclosure casting (?) like a particularly beefy beer keg, and then a few grams of weight shaved with the internal chassis punchings. I suppose it convinces those appraising it that some effort has been made. |
12th Aug 2018, 10:16 pm | #12 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Is this a Rebecca unit ?
Nothing to do with the unit I suppose but Marconi went for cylindrical casing with the Silvita lifeboat Tx/Rx.
Lawrence. |
12th Aug 2018, 11:03 pm | #13 | |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,396
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Re: Is this a Rebecca unit ?
Quote:
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13th Aug 2018, 8:40 am | #14 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: Is this a Rebecca unit ?
Cylindrical casings came into use in aircraft equipment post-war as a result of wartime experience. Equipment returning from a bombing mission at high altitude (for the time) would be soaked through with condensation in the unpressurised fuselage of a Lancaster or Halifax. You can read reports of it all being removed after a flight, dried out, and refitted for the next. Apart from the effort involved, it must have caused major reliability problems with connectors being repeatedly broken and remade.
So casings were introduced where the insides were installed dry and warm, and then the casing pressurised, often with nitrogen rather than air, through a valve akin to that on a bicycle tyre. A desiccator absorbed any residual water. |
13th Aug 2018, 1:01 pm | #15 | |
Heptode
Join Date: Jun 2012
Location: Southeast Norfolk, UK.
Posts: 773
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Re: Is this a Rebecca unit ?
Quote:
Regards Roger |
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13th Aug 2018, 2:36 pm | #16 |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,095
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Re: Is this a Rebecca unit ?
I would say that this is not a set to test Rebecca, it IS a Rebecca unit but with lots of diagnostic features and knobs, for checking out a whole Rebecca-Eureka system.
Clearly it is an airborne unit with a pressurised housing that helps with corona discharge of compact transmitters. |
13th Aug 2018, 3:06 pm | #17 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: Is this a Rebecca unit ?
George, sorry but I don't agree!
The AP for Rebecca Mk4 can be downloaded from the VMARS archive. Look at page 127 of 137 in the pdf, this test set is mentioned briefly, albeit with no details. It is not an airborne unit, but I surmise that the designers used a lot of existing parts from the airborne equipment. Andy |
13th Aug 2018, 3:40 pm | #18 |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,095
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Re: Is this a Rebecca unit ?
Oh yes, Andy is right. I had missed that particular AP for some reason.
I guess they just built it in a handy airborne unit. |
14th Aug 2018, 2:33 pm | #19 |
Pentode
Join Date: May 2011
Location: Enniskillen, Fermanagh, UK.
Posts: 188
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Re: Is this a Rebecca unit ?
Thank you for the information. More interesting than I thought. The owner does not do internet, seldom uses the phone with most comms via ham radio, thus the delay in my updates.
Andy, PM sent. Cliff. |