S V D - 9

The "SVD" line receivers ("Superheterodyne All-wave with a Loudspeaker") were the first really reliable multi-tube sets capable to compete with the makes of the leading Western countries. Their prototypes were the contemporary sets produced by the American companies "Zenith" and "RCA". Production of sets of this series was started in end-1937 at the Works No.3 of the People's Commissariate of Communications in the town of Alexandrov. During one year 3 modifications of the set were produced. The first of them - the "SVD-1" was put out in small lots and was assembled on RCA glass valves, which were not produced in the USSR. At the same time working out of better and more stable metallic tubes was under way and some months later the Alexandrov Works produced a set model "SVD-M" on home-made metallic tubes. In this set the "magic eye" tuning indicator was installed for the first time in Soviet receivers. The "SVD-9" model has some schematic changes as compared with the basic model. In the author's collection the "SVD-9" set is of the first modification produced in 1938, has an outer design similar to that of the "SVD-M" (a round scale). Its chassis has the serial number 12816. In the next lots of the "SVD-9" receiver its design was slightly changed (the scale was stretched horizontally). In some lots of the set metallic tubes imported from the USA were installed (made by RCA, Ken-Rad etc.)

BASIC TECHNICAL DATA.

 

Set of tubes: 6K7, 6K7, 6A8, 6K7, 6X6, 6F5, 6L6, 5C4, 6E5

Tuning range:

LW (A) 750-2000 m

MW (B) 200-556 m

SW1 (G) 33,3 - 85,7 m

SW2 (D) 16,7 - 36,6 m

Sensitivity 20 - 50 mkV

Intermediate frequency - 445 Hz

Power consumption 100 W

Power output 3-5 W

Dimensions 560 360 290 mm

The set is assembled in a massive tower-shaped case covered with varnished veneer of two shades.All the regulating handels are on the front side. The round scale of the aeroplane type is protected with glass and in the center it bears an emblem in the form of the globe in the background of the Soviet symbols: the Star, the Sickle and the Hammer.

Above the scale the screen of the "magic eye" tuning indicator is placed which is covered by a visor making it even more similar to an eye. There are four control handles. The upper row from left to right begins with the band selector (A,B,G,D-positions), then come the tuning and the volume control handles. The tone control knob combined with the AC switch is located below.
The tuning handle has a reductor transforming the rotation to the cap shaft with the help of a metallic spring friction muffler. The detachable back cover gives access to the high box-shaped chassis. On the back side of the case a small shield is fastened that bears the inscription: "g.Alexandrov SVD-9 4248 UPP-NKS". The switching of the AC tension (110-127-220 V) is made by a traditional way of those times - resetting the jumpers on a special panel. A fuse is also placed on it. The panel is covered by a steel sliding case. The power transformer is put into a metallic screen. The oxide caps of the source filter are of the "wet"-type.
All the RF and oscillator coils are assembled as a separate screened section fastened to the chassis with four screws. The tuning cap has four sections and is installed on shock absorbing layings and covered with a cardboard case. The band selector is 3-plated. The loudspeaker is dynamic-type, with the series sourcing of the field coil. The outer transformer is inclosed in a case and put on the "basket" of the loudspeaker.

ELECTRIC DIAGRAM.

The "SVD-9" set is a 9-tube superheterodyne. A pecularity of its scheme is the additional step of RF amplification which workes only in the shortest wave band ("D"). Such a complication has become necessary because of worse sensitivity in higher frequencies as a result of using the pentagrid 6A8 as an oscillator-mixer. And besides, the extra RF step increases the selectivity in "D"-band up to the level of the other bands. On all tuning bands the local oscillator frequency is higher than the receiving frequency to the value of the IF, while in the "D"-band it is lower than the receiving frequency to the same value. The two diodes of the 6X6 valve are used for AFdetecting and forming the auto gain control signal. A two-step AF amplifier is built on a 6F5 triode and output 6L6 tetrode. The metallic kenotrone 5C4 works in a rectifier of usual scheme. Using the optic vacuum tuning indicator - the 6E5 tube - was an innovation of the set.This tube was also worked out in 1937 first in the USA but very soon after it was produced in this country.Imported paper hermetizied "microfarade" caps are installed in the set, the rest are paper "induction-free" and pressed mica ones. RF mica caps of an open construction are also used. Some resistors are imported ("Dralowid"), the rest are the "Kaminsky" resistors.

The quality of performance of a well-alligned "SVD" set makes a pleasant impression. While listening in, one soon forgets that it was produced as early as 1930's. The receiver can compete with the Class 1 sets of 1960's which were assembled on Noval tubes. Its output was an undoubted success of the Soviet industry of the pre-war time.