Radio receiver "GEOLOG" (made in USSR, 1971)

Owing to the continuous development of the receiver there might be discrepancies between the design, electric circuit and their description given in the present Instructions.

IMPORTANT

Before switching on the radio receiver, carefully read the Operating Instructions. Immediately remove the exhausted batteries from the receiver.

BRIEF DESCRIPTION

The radio receiver "GEOLOG" is a superheterodyne hooked up with twelve transistors.

It is used to receive radio broadcasts in the long, medium (with magnetic built-in antenna) and short waves (with telescopic antenna).

Power is supplied from an inside 9 V battery consisting of six cells type 373.

The radio receiver uses the following transistors (Fig. 1): GT322B - heterodyne; GT322A (2 pcs) - HF amplifier and mix­er; GT309B (2 pcs) - two stages of LF amplifier; MP41 (3 pcs)- two stages of LF amplifier and LF driver stage; KT315B - the third stage of LF amplifier; MP38 - LF driver stage; GT402E - output stage of LF amplifier; GT404B - output stage of LF amplifier (Fig. 1).

Circuit diagram of Radio receiver GEOLOG
Click to enlarge

Fig.1. Superheterodyne radio receiver "GEOLOG" circuit diagram.

SPECIFICATIONS

Operating Waves and Frequencies:

Long waves (LW)2000 to 735.3 m (150 to 408 kHz)
Medium waves (MW)571.4 to 186.9 m (525 to 1605 kHz)
Short waves (SWI)75.9 to 47.6 m (3.95 to 6.30 MHz)
Short waves (SWII)42.5 to 41.1 m (7.05 to 7.30 MHz)
Short waves (SWIII)31.8 to 30.7 m (9.45 to 9.80 MHz)
Short waves (SWIV)25.5 to 24.8 m (11.75 to 12.10 MHz)
Intermediate frequency465±2 kHz
Maximum sensitivity with built-in ferrite antenna reception, mV/m, not worse than:
in LW band
in MW band
0.8
0.5
Maximum sensitivity with telescopic antenna reception in SWI-SWIV range, μV/m, not worse than100
Actual sensitivity with built-in ferrite antenna reception, μV/m, not worse than:
in LW band
in MW band
2.5
1.5
Actual sensitivity with telescopic antenna reception in SWI-SWIV range, μV/m, not worse than400
Output power, mW7000
Overall dimensions, mm290x19xX90
Mass of receiver with power battery, kg2.8

OPERATION

SWITCHING ONSwitch on the receiver and adjust the volume, turning volume control knob 1 (Fig. 2) clockwise.
TELESCOPIC ANTENNAIn case of short wave reception pull out the telescopic antenna, first holding it by the head, then by each elbow one by one to the limit of travel (9 elbows altogether). The antenna is provided with a hinge to prevent damaging it from accidental lateral loads and to enable it to be set in any position.
SWITCHING BANDS OVERTo select the required wave band depress one of the six buttons 4 of the band selector switch.
TUNINGTuning to a station is with tuning knob 6.
TONE CONTROLTone control knob 2 is used to obtain a tone more pleasing to the listener.
SCALE BIAS LIGHTINGFor convenience of use at night the receiver is provided with a scale bias lighting and the surface behind the scale has a fluorescent coating. To illuminate the scale depress button 3.
OUTDOOR ANTENNABesides the telescopic and built-in ferrite antennas, use can be made of an outdoor (external) antenna which is connected to jack 9.
EARPHONERadio programs can be listened in over the earphone which is connected to jack 8. With the earphone connected the loudspeaker is switched off automatically.

radio receiver GEOLOG - view from outside

Fig.2. General view of the radio receiver "GEOLOG":
1 - volume control knob; 2 - tone control knob; 3 - scale illumination button; 4 - band switch button; 5 - telescopic antenna; 6 -tuning knob; 7 - external supply jack; 8-earphone jack; 9 - external antenna Jack; 10 - earthing jack; 11 - lower cover.

FITTING POWER BATTERY

Remove the two screws which attach the lower cover and take off the latter.

Put in or replace the battery in accordance with Fig. 3, paying special attention to the correct positioning of the cells. The receiver will be damaged, if the battery is reversed.

Re-install the lower cover and turn home the screws.

battery installed in radio receiver GEOLOG

Fig.2. Fitting power battery: 1 - power cells

LIST OF STANDARD EQUIPMENT

Radio receiver - 1 pc
Cells 373 - 6 pcs
Earphone TM4 - 1 pc
Packing box - 1 pc
Certificate - 1 copy

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