D/F Loop for R1155 - UK Vintage Radio Repair and Restoration Discussion Forum

Mike Brett · 2nd Sep 2006, 9:38 pm

Hello all
I am trying to make an exact copy of a direction finding loop for a R1155. I have the general layout and wiring, but what I do not have is the actual dimensions of the unit. Has anyone built or got an original loop that they could measure for me. All I need is the outside diameter of the internal ring, the overall diameter of the wire loop and the width of the wire supports. I can work the rest out from this. Any help would be great.
Regards Mike 2E0LTJ.

jim_beacon · 2nd Sep 2006, 9:44 pm

Mike,

there is more than one type. isuggest making enquiries to the RAF museum at Hendon, or the Duxford Radio Society.

Jim.

YC-156 · 3rd Sep 2006, 7:42 am

How would you know if you got one?

I have a smallish WW-II era DF loop of British or american origin, but not at all sure about the type.

Mind you, I haven't actually checked to see if there might be a type number stamped into it somewhere.

Frank N.

YC-156 · 3rd Sep 2006, 8:05 am

Just checked it, and while it is definitely of either US or British origin (ball bearing 'Made in U.S.A.', loop casting marked with 'Front'), there are no type designators anywhere.

JHGibson · 4th Sep 2006, 2:39 am

Mike, the Air Ministry manual for the R1155 gives some details of loop aerials 3 and 4, with 4 being the simpler. An exact copy could be a challenge but you could probably make something that would work.

Type 4 consists of a 10 inch diameter former with 16 spaced turns of #18 SWG. This coil has an inductance of about 100 uH and has a natural resonance of about 3.5 mcs with the distributed capacity of the installed system. There is an electrostatic shield over the coil of one turn of sheet metal of about 11 inches diameter. The ends of the sheet metal are insulated from each other so it does not make a shorted turn. The shield forms a short cylinder only slightly wider than the coil winding.

The loop is connected to the receiver through a two conductor low capacity shielded cable described as Dumet 4. The cable run is only some 5 to 6 feet max.
John.

John H. · 4th Sep 2006, 11:00 am

Hi Mike,
Some further info re the D/F loop for you.

The Loop Aerial Type 3, A. M. Ref No 10B/10594 open wire type, was the one generally used, in Lancasters anyway. I have replicated it myself and it works very well.

It is made on a former 10 inches in diameter with a mounting base and terminal plate.
Around the periphery of the former 12 slotted supporting spreaders are fitted to carry the loop windings, spaced at 30 deg (as per a clock face).

The loop itself consists of 16 turns of 18 SWG bare tinned copper wire. (R.S sell it , stock No 355-057)
The wound loop must have an overall diameter of 11 inches and is 3 inches wide.

The feed to the Rx is 2 wire screened cable. If you don`t have the correct `C` shaped Plug Type 209, a pre-set air spaced variable cap of 75 Pf will be required at the plug end across the loop pair to tune for maximum sensitivity.

On the plug, pins 13/14 are earth and pins 15/16 are the loop input.

A later Loop Type 4 A.M. Ref No 10B/420 with copper electrostatic shield is 7.5 inches dia with 20 turns of 20 swg wire and all enclosed in a bakelised fabric housing.

Hope this helps out, its well worth making and adds to the authenticity of using the 1155.
John H.

GMB · 10th Sep 2006, 7:42 pm

For those who don't know what it looks like, here is a photo of a rather grubby one. (pm me for others and higher resolution).

Mike Brett · 19th Sep 2006, 5:32 pm

Hi
Sorry I was a long time coming back but thanks very much to all who replied. I can and will build a very good copy from all the information I recieved.
Regards Mike.

2nd Sep 2006, 9:44 pm	#2
jim_beacon Retired Dormant Member Join Date: Mar 2003 Location: Bishop's Waltham, Hants, UK. Posts: 939	Re: D/F Loop for R1155 Mike, there is more than one type. isuggest making enquiries to the RAF museum at Hendon, or the Duxford Radio Society. Jim.

3rd Sep 2006, 7:42 am	#3
YC-156 Retired Dormant Member Join Date: May 2005 Location: Aarhus, Denmark Posts: 281	Re: D/F Loop for R1155 How would you know if you got one? I have a smallish WW-II era DF loop of British or american origin, but not at all sure about the type. Mind you, I haven't actually checked to see if there might be a type number stamped into it somewhere. Frank N.

3rd Sep 2006, 8:05 am	#4
YC-156 Retired Dormant Member Join Date: May 2005 Location: Aarhus, Denmark Posts: 281	Re: D/F Loop for R1155 Just checked it, and while it is definitely of either US or British origin (ball bearing 'Made in U.S.A.', loop casting marked with 'Front'), there are no type designators anywhere.

4th Sep 2006, 2:39 am	#5
JHGibson Retired Dormant Member Join Date: Apr 2003 Location: Salt Spring Island, BC, Canada Posts: 368	Re: D/F Loop for R1155 Mike, the Air Ministry manual for the R1155 gives some details of loop aerials 3 and 4, with 4 being the simpler. An exact copy could be a challenge but you could probably make something that would work. Type 4 consists of a 10 inch diameter former with 16 spaced turns of #18 SWG. This coil has an inductance of about 100 uH and has a natural resonance of about 3.5 mcs with the distributed capacity of the installed system. There is an electrostatic shield over the coil of one turn of sheet metal of about 11 inches diameter. The ends of the sheet metal are insulated from each other so it does not make a shorted turn. The shield forms a short cylinder only slightly wider than the coil winding. The loop is connected to the receiver through a two conductor low capacity shielded cable described as Dumet 4. The cable run is only some 5 to 6 feet max. John.

4th Sep 2006, 11:00 am	#6
John H. Retired Dormant Member Join Date: Nov 2005 Location: West Sussex, UK. Posts: 51	Re: D/F Loop for R1155 Hi Mike, Some further info re the D/F loop for you. The Loop Aerial Type 3, A. M. Ref No 10B/10594 open wire type, was the one generally used, in Lancasters anyway. I have replicated it myself and it works very well. It is made on a former 10 inches in diameter with a mounting base and terminal plate. Around the periphery of the former 12 slotted supporting spreaders are fitted to carry the loop windings, spaced at 30 deg (as per a clock face). The loop itself consists of 16 turns of 18 SWG bare tinned copper wire. (R.S sell it , stock No 355-057) The wound loop must have an overall diameter of 11 inches and is 3 inches wide. The feed to the Rx is 2 wire screened cable. If you don`t have the correct `C` shaped Plug Type 209, a pre-set air spaced variable cap of 75 Pf will be required at the plug end across the loop pair to tune for maximum sensitivity. On the plug, pins 13/14 are earth and pins 15/16 are the loop input. A later Loop Type 4 A.M. Ref No 10B/420 with copper electrostatic shield is 7.5 inches dia with 20 turns of 20 swg wire and all enclosed in a bakelised fabric housing. Hope this helps out, its well worth making and adds to the authenticity of using the 1155. John H.

2nd Sep 2006, 9:38 pm	#1
Mike Brett Retired Dormant Member Join Date: Dec 2005 Location: Wisbech, Cambridgeshire, UK. Posts: 452	D/F Loop for R1155 Hello all I am trying to make an exact copy of a direction finding loop for a R1155. I have the general layout and wiring, but what I do not have is the actual dimensions of the unit. Has anyone built or got an original loop that they could measure for me. All I need is the outside diameter of the internal ring, the overall diameter of the wire loop and the width of the wire supports. I can work the rest out from this. Any help would be great. Regards Mike 2E0LTJ.

10th Sep 2006, 7:42 pm	#7
GMB Dekatron Join Date: Aug 2003 Location: near Reading (and sometimes Torquay) Posts: 3,099	Re: D/F Loop for R1155 For those who don't know what it looks like, here is a photo of a rather grubby one. (pm me for others and higher resolution). Attached Thumbnails

19th Sep 2006, 5:32 pm	#8
Mike Brett Retired Dormant Member Join Date: Dec 2005 Location: Wisbech, Cambridgeshire, UK. Posts: 452	Re: D/F Loop for R1155 Hi Sorry I was a long time coming back but thanks very much to all who replied. I can and will build a very good copy from all the information I recieved. Regards Mike.