LiSpr 80, side 2


Serial no. 217675, year 1940

This is a 2-way audio communication equipment.
The signal is transferred on a light beam from a 5-watt bulb.

The light beam is modulated with a light phase modulator.
The light beam is AM-modulated with a moving prism.
The position of this prism is manipulated of the transmitter audio amplifier.

Red and IR filter can be inserted in the beam.
Receiver and transmitter have one lens each.
Light detector is placed 250 mm behind the receiver lens.
Diameter on the light detector is less than 1 mm,
so the direction of the unit is very important.
Diameter of the light beam is only 1.4 meter at 250 meter from the transmitter lens.
This will give a diameter of 7 meter 1 km away.
An RV2P800 tube is connected directly to the light detector as a preamplifier.
Diameter on the receiver and transmitter lens is 80 mm.
Manufactured by Carl Zeis Jena.

Technical data from the handbook:

Optic Receiver - 80 mm
Transmitter - 80 mm
Tubes Receiver, 3 - RV2P800
Transmitter, 2 - RV2P800
Detector Thalofidezelle
Filters Reed, visible
Reed, IR, invisible
Range 4 km without filter
4 km with reed filter
2-3 km with IR filter
Power 2 VDC, filament
4.8 VDC, bulb
50 VDC, detector
60 VDC, anode voltage


Left, light detector.----------------------------
Mid, direction finder telescope.---------------
Right, filter selector. ---------------------------
Under, preamplifiers tube.----------------------
Tripod is also manufactured by Carl Zeis Jena. -

Optic unit in the case.

Serial no. xxxx, year 194x, ------- Serial no. xxxx, year 194x

Amplifier unit with RV8P800 tubes.

Spare parts. Carbon Microphone, light detector, bulb 4.8V- 5W

Optic unit.
A – light filters. 4 different filters can be selected with the filter knob.
B – Light modulator with a moving mirror.--------------------------
C – Light source with 5 Watt bulb.---------------------------------
D - Light detector.-------------------------------------------------
E – RV2P800, Light detector Amplifier tube.----------------------
F – Telescope for adjustment of direction.--------------------------

Light-modulator (11). Filters (IR and red).

Her we have the light phase prism mounted on the moving iron.

Left - Here is the light detector behind the cover.
Right – Here is the filter selector.-----------------

Light Detector. Look at component 26 in the schematic (node 2 and 17)
Detector is mounted on a porcelain structure. This gives a very stabile fastening of the detector.

Light Detector amplifier tube and light bulb.

Light bulb 4.8 V, 5 W.

Stativfestet. Skruer for sideretting og høyderetting av optikken.


Here is the schematic located inside the amplifier unit.
Components left of the dotted line is located inside the optic unit.

Li Spr 80, part one