Mk IX Sextant Lamp Polarities

The Mk IX sextant lamp holders have a pair of co-axial rings for contacts. The outer ring connects to the body of the lamp, the milled section. It is this connection's polarity that is noted here, either + P or - N.
An easy check method is to connect an Ohm meter between the battery case base ring (where the cap screws on) and the outer ring of the socket or the milled body of the lamp. Continuity indicates what I call a -N connection.
Sextant Model Bubble Position Handle Position
Mk IX:
No. 299/42 +P -N
No. 504/40 -N -N
No. 731/42 +P +P (no bubble prism!)
No. 870/39/40 +P +P (SS&S Early)
No. 3960/40 -N -N
No. 4083/ -N +P
No 4989/40 -N -N
No. 5437/40 -N -N
No. 6021/40 +P +P
No. 6083/ +P ? (Socket dead)
No. 6548/ +P +P
No. 6922 +P -N
No. 14535/40 +P -N
No. 15551/40 +P +P No. 18156/40 -N +P
Mk IX A:
No. 10962/ -N -N
No. 1102/43 -N -N
No. 1119/41 -N +P
No. 6209/41 -N +P
No. 6622/41 -N +P
No. 7607/42 -N -N
No. 1607/42 -N -N
No. 4134/43 -N +P
No. 5055/43 -N +P
No. 6465/41 -N +P
No. 7189/41 -N +P
No. 7123/ -N +P
No. 7358/42 -N +P
No. 7933/41 -N -N
No. 9089/42 -N +P
No. 9801/43 -N +P
No. 9917/42 -N -N
No. 14750/42 -N +P
Mk IX B:
No. 3918/44 +P +P
Mk IX AM:
No. 2596/43 -N ? (Socket dead)
No. 5610/41 -N +P

 

Mk IX BM:~
Unknown (I P) -N -N
No. 2521/44 -N -N
No. 1622/44 +P -N
No. 9944/44 -N -N
No. 10591/44 -N ? (Socket dead)
No. 10926/43 -N -N
No. 12209/43 -N -N
No. 12472/43 -N -N
No. 12940/43 -N -N
No. 13019/43 -N +P
No. 13387/43 -N +P
No. 13855/43 -N +P
No. 14805/43 -N -N

Last update 20/01/12 PB.

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