There is an angle-measuring reticle (Figure 5) in the field of view of the right telescope of the
binoculars. Positioned in the centre of the reticle are cross-hairs and five circumferences with radii
expressed as divisions of the deflection: 0-05, 0-10, 015, 0-20, 0-30.
One division of the deflection is written as 0-01 and equal to 3.6.
The circumferences with radii of 0-05 and 0-15 are marked with dashes, the distance between the
dashes is equal to 0-01. The circumferences with radii of 0-10, 0-20 and 0-30 are solid and figured. The
cross-hairs positioned in the reticle centre has the lines of 0-02.5 long beginning from the centre. Along
the horizontal and vertical diameters of every circumference there are the lines with a length of 0-01
marked from the inner side of the circumference. The changeable light filters (neutral and light-orange
ones) are put on the eyepieces if necessary. The neutral light filters are used at bright light, for example,
by sunny day, the light-orange ones are used when it is dull in order to increase the contrast of the object
to be observed.
When sighting to the objects located in the sun, the sunlight may penetrate into the telescopes and
make worse visibility. Therefore blinds 1 (Figure 2) are put on the casings of the telescopes to prevent
penetration of sunshine. Besides, the blinds protect the objectives against possible scratches.
For easy observation the binocular telescope is provided with soft elastic rubber headrest 9 (Figure 3).
The headrest can move in the axial and transverse directions to align an observer’s pupils and exit
pupils of the device.
Dehydrator plugs 3 (Figure 2 ) intended for protection of the optical pieces inside the device against
sweating are secured in the lugs positioned in the lower section of the telescopes. The action of the
dehydrator plug is based on capacity of silica gel which constitutes the basic part of the plug to absorb
moisture from the ambient air.
The silica gel condition is controlled through protective glasses: dry silicagel is bright blue; silica gel
saturated with moisture is light-pink or dirty-white. The caps of the desiccators are provided with slots for
a wrench which is used for their unscrewing in case of replacement.
When the inner surfaces of the optical pieces are sweated due to operation with the device at the high
humidity of the ambient air one can desiccate the inner cavity of the device with dry air through the holes
closed with caps 9 (Figure 1) and 2 (Figure 2).
Level 5 (Figure 3) serves for levelling the device. Three concentric circumferences are marked on the
outer surface of the vial, they are used for determination of the device levelling accuracy. The level
division value is 0-02.
The angles of sight in the vertical plane are read in the range from minus 18° (3-00) to plus 84° (14-00)
from scale 7 and by the nonius secured rigidly in the bracket. Readings are taken from the scale through
the port closed with a transparent plate inserted in cover 6. The scale is divided into one hundred seventy
divisions, in so doing thirty divisions which designate negative angles of position (below the horizon) are
painted red, and one hundred forty divisions which designate positive angles are painted white. A division
value of every division is equal to 0-10. Every one hundred divisions are designated with figures 3, 2, 1,
0, 1, 2, 3, 4....14. The nonius allows of reading angles with accuracy up to 0-02.
The binoculars are locked by a position angle in the required position with the help of handwheel 8
(Figure 1).
There is a hole for lubrication of the axle on the right eye of the outer bracket. The hole is closed with
screw 13.
For determination of angles of traverse there is the scale of traversing angles. The division value of
every division is equal to 0-10. Every one hundred divisions are numerated with figures from 1 to 59. The
nonius allows to take readings from the limb with accuracy of 0-02.
For rotation of the limb relative to the binocular telescope in orientation one makes use of a stopper.
Handwheel 14 (Figure 3) of this stopper is positioned under the limb as well as three dogs 4 which help
to rotate the limb through any angle when handwheel 14 is released.
The binoculars rotation about the vertical axis of the immovable base of the limb can be stopped by
using handwheel 11 of the brake located in the lug of guide bushing 12.
The right telescope of the binoculars of device PNB-3 embodies a dove-tail guide secured with screws,
it carries tell-tale pipe 11 (Figure 1). The tell-tale pipe 11 is secured on the dove-tail guide with the help of
a hand-wheel. The upper section of the casing of the tell-tale pipe has approximate sight 8 (Figure 3) for
aiming the device at the object, the sight consists of a front sight and a backsight.
The tell-tale pipe is a cranked telescopic monocular optical system. It consists of an objective,
prism, eyepiece, reticle and light filter. The optical pieces of the tell-tale pipe and those of the binoculars
are designed for the same purpose. The reticle of the tell-tale pipe is provided with cross-hairs,
circumference of 0-20 radius and lines in the vertical and horizontal planes (at every 0-05 inside the
circumference and at every 0-10 outside it)
,
figure 6.
In operation with device PNB-3 at night one makes use of a lighting unit which consists of a distribution
box, lamp-holders 12 (Figure 1), portable lamp 3, a plug coupling and wires. Accumulator 17 serves as a
supply source of the system. For illumination of the reticle and scales one uses electric lamps of 2.5 V in
the lamp-holders and portable lamp. With the help of a cut in the shape of a dove-tail and a catch one
