VOLNA-K
The Volna-K is a Russian Navy HF receiver. It was intended as a maritime
receiver for the Navy and for commercial shipping. It is a superheterodyne
double conversion HF receiver, using 17 miniature valves, and 2 semi-conductor
diodes. The valves have Russian numbers, but are equivalent to common American
types. It can run off 110 or 220 volts AC, or 28 volts DC. It is intended
to receive AM and CW signals down to 0.5 uV levels. The word "volna"
translates to "wave". The frequency coverage is 12 kHz to 23 mHz in 9 bands,
with gaps around the IF frequencies. There are 3 versions of the Volna-K,
each with a slightly different frequency coverage. There is also Volna-P
which is the version for submarines.
VOLNA-K VOLNA-K1
VOLNA-K3
Band 1 12 - 60 khz
12 - 60 khz 12
- 60 khz
Band 2 100 - 180 khz
100 - 180 khz 60
- 100 khz
Band 3 180 - 330 khz
180 - 330 khz 100 -
180 khz
Band 4 300 - 600 khz
300 - 600 khz 180 -
330 khz
Band 5 1.5 - 2.8 mhz
600 - 1100 khz 330 - 600 khz
Band 6 2.8 - 5.0 mhz
1.1 - 1.6 mhz 600 - 1100 khz
Band 7 5.0 - 9.0 mhz
5.0 - 9.0 mhz 1.1 -
1.6 mhz
Band 8 9.0 - 15.0 mhz
9.0 - 15.0 mhz 1.6 - 2.8
mhz
Band 9 15.0 - 23.0 mhz 15.0 -
23.0 mhz 2.8 - 5.0 mhz
Figure 1. Volna-K front view
MANUFACTURE
It was made in the Petropavlovsky Radio Factory, in Kirov, USSR.
About 70,000 were made from 1959 to 1985 (this one is dated 1969). It
was available in grey hammertone or green, with engraved legends. The
Volna-K weighs 87 pounds. It is a development of the Melnik receiver
from 1949, also made in the same factory. The word "melnik" translates
to "flower". The Melnik has the same physical shape (taller than it is
wider) with a very similar control layout, the obvious differences being
the dial, the aerial input, and the speaker. The controls that are in the
same position are, BFO select, IF gain, tuning, bandswitch, AF gain, meter
switch, BFO note, and the meter. The Volna-K is also similar in size, function,
construction, and weight, to the English B40 Navy receiver.
CONTROLS
This radio was not intended for export, so all the controls are labeled
in the Russian language, using the CYRILLIC script, so it is difficult to
read, but luckily the numbers are the same. There is a speaker in the top
left hand corner, which has a cloth baffle on the rear of it. Below the speaker
is the BFO switch which is OFF in the left hand position, ON in the middle
position, and turns ON the CRYSTAL CALIBRATOR in the right position. The
calibrator is controlled by turning the heater on and off, so it takes several
seconds to start, and longer to stop. The calibrator can provide markers
at 100 khz or 1 mhz positions, selected by setting an internal switch. There
are two crystals inside the radio, in cylindrical crystal holders. Turning
the valve heater off, increases the life of the valve by avoiding "cathode
poisoning". Below this control is the IF BANDWIDTH selection switch, which
allows 6 khz, 1.5 khz and 0.5 khz bandwidths. Below this switch is the IF
GAIN control, and below this again is the headphones socket. This socket
is a 2 pin type which is used on many Russian receivers and transmitters and
similar to the type used on 1940s German military equipment.
At the top right hand corner is a meter, which is used to indicate the
valve current of each receiver valve. It has a simple scale with a centre
green section, to indicate the healthy state of the valves. Below the meter
is the BFO PITCH control which allows the operator to tune in CW (morse)
or to resolve SSB (single sideband) signals. Below this control is a short
stubby shaft projecting through the front panel. It has a large WARNING label
next to it, as this is used to adjust the oscillator, and so it affects the
receiver calibration. It is intended to be used with the crystal calibrator,
to set the frequency for each band. It needs to be pushed in and turned to
adjust the frequency, so it cannot be accidentally bumped. Below this is the
METER SELECT switch which has 10 positions to allow the valve current to
be monitored. The HT rectifier, voltage regulator, current regulator, and
the two crystal calibrator valves are not monitored. Below the meter switch
is the AF gain control, and below this is another headphone socket.
In the centre of the front panel, is the large semicircular dial (used
for coarse frequency setting), and an optical frequency readout above it
(for fine frequency setting). The maritime distress frequencies are marked,
500 khz and 2182 khz. It takes 40 turns of the heavy flywheel knob to go
from band end to end, which is about 9 feet of tuning scale on the ground
glass screen. A label indicates the resolution of each band, 250 hz for
band 1, 500 hz for bands 2 and 3, 1 khz for band 4, 2 khz for band 5, 5 khz
for bands 6 and 7, and 10 khz for bands 8 and 9. Below the dial is a raised
panel, which has the main TUNING knob and the BAND SELECT switch on it.
The BAND SELECT switch is pulled out from the lock position, you rotate it
to change bands, then you push it back in. A small window shows the band
selected. The panel also has the POWER ON switch, the SPEAKER ON switch and
the AGC ON switch at the right. In the centre is engraved the name and serial
number. The serial number has the date as the first 4 digits. At the bottom
is the mains fuse.
DESCRIPTION
The Volna-K is a double conversion superheterodyne LF and HF receiver.
It is single conversion on bands below 600 kHz. The first IF is 915 kHz
and the second IF is 85 kHz, and there are gaps in the frequency coverage
to allow for this, 60-100 khz and 600-1500 khz.
The aerial enters the receiver through a low pass filter, and then goes
to a gas discharge arrestor. The arrestor would be for protection from static
build up, or damage from nearby transmitters. The low pass filter would help
reducing RADAR signal interference. The solid alloy turret has 4 tuned circuits
per band, 2 cascaded circuits for the aerial tuning, one for the single RF
stage (6BA6), and one for the first oscillator (6AS6). Each circuit is enclosed
in its own alloy box. There is a 4 gang tuning capacitor in a cast alloy frame,
the oscillator capacitor being much larger. The mixer output (6BE6) then
goes to the first IF (915 khz), which has 3 valves and 3 tuned circuits (the
IF amplifier 6BA6, mixer 6BE6 and oscillator 6AS6) also in individual alloy
boxes. This IF amplifier is not used below 600 khz. The next IF (85 khz)
also has 2 valves (6BA6), and 3 tuned circuits. The first 2 tuned circuits
are the bandpass filters, each one consisting of 3 inductances and several
switched capacitors. These are also in individual alloy boxes. It has 3 selectable
bandwidths, 6 khz, 1.5 khz, and 0.5 kHz. The AGC amplifier (6AS6) picks off
the IF signal here, and uses a diode rectifier (OA91) to generate the AGC.
The AGC is applied to both mixers, both IF amplifiers, but not the RF amplifier.
The receiver has tremendous gain, and overloads easily when the AGC is turned
off. The main IF output is rectified by a diode (OA91) and there is an audio
pre-amplifier (6AS6) and a power output amplifier (6AQ5), for the internal
speaker or the audio line output. There is negative feedback on the audio
stages. The BFO is a single valve (6AS6), which is injected into the last
IF. The crystal calibrator oscillator (6AS6), has 2 crystals for different
marker frequencies (1 mhz and 100 khz), and a divider (6AS6) for the lower
bands. It has a conventional power transformer and double diode rectifier
(5U4). The primary can be set for 110, 127, and 220 volts AC. There is a
voltage regulator valve for the oscillator HT voltage and a barreter for
current regulation of the oscillator heater. The mains power supply unit could
be replaced by an optional 24 VDC supply.
Figure 2. Mains Power Supply Unit (barreter, rectifier, regulator)
There is no signal strength meter, but the meter can be switched to show
the anode current in each of the 10 active valves. The current changes
with signal strength, so this can be used as an indication. The internal
crystal calibrator, and a front panel oscillator trim control, allows the
dial to be set precisely. Most of the valve cathodes are connected directly
to earth, without generating cathode bias. The exceptions are the oscillators,
which are electron coupled type, and so the cathode is connected to the
oscillator coil. The audio output valve has cathode bias, and so does the
audio preamplifier. The only other exception is the RF amplifier which also
has cathode bias.
The mechanical construction is of high quality, using several aluminium
cast chassis, and the large turret for the band change. The internal chassis
are modular and removable, and each tuned circuit has its own cast box.
The wiring is with white plastic wire, probably PTFE. All the modules and
wiring is easy to get at, with no hidden or inaccessible components. All solder
joints have been painted with red varnish. The gear box that drives the tuning
capacitor and frequency scales is nice to use and has no backlash.
The manual is in Russian. It has the coil winding data for each coil,
and the valve pin numbers and descriptions. There is a comprehensive parts
list, circuits, physical wiring diagrams, and mechanical drawings of the
tuning dial drive gearing and the optical projection system.
Figure 3. Diode Detector
RESTORATION
The radio was very clean when received from St. Petersburg. It required
a new mains cord and aerial coax, as they are attached to the case, and
loop internally to the chassis. I found that by using the 220 VAC tap on
the mains transformer, that the internal voltages were about 10% too high
when connected to 240 VAC, so I rewired it for 110 VAC and used an external
step down transformer. The radio worked but was noisy and insensitive, and
the BFO was unstable. I cleaned and lubricated the IF and AF gain
controls and the BFO control, which corrected this. The main tuning knob
was loose. I began an alignment and found that the first IF slugs were expoxyed
in place, and impossible to move without breaking them. I placed a small
capacitor trimmer across them and managed a successful alignment, as all
5 were high in frequency. There was broadcast band breakthrough on the 1.5-2.8
mhz band, but this was removed with the correct alignment. The second IF
slugs were sealed with wax so they were easy to reset. There are 15 tuned
circuits as they also set the 3 IF bandwidths. When finished, the sensitivity
had improved to 22 microvolts into the second mixer grid for 10 dB
S/N. The 9 bands were then aligned and gave sensitivities of: Band 1: 10
uV, Band 2: 3 uV, Band 3: 3 uV, Band 4: 1 uV, Band 5: 1 uV, Band 6: 0.5 uV,
Band 7: 1 uV, Band 8: 2 uV, and Band 9: 4 uV. It is difficult to use
the optical scale when the receiver is out of its case, due to ambient light.
There were no components that needed replacing, all resistors, capacitors
and valves were fine.
SHORT COMINGS
The obvious short coming is its weight, so you would not want to move
it very often. The IF gain control is very near the tuning knob, and is easily
bumped. The radio could be improved if the control was farther away or if
there was more bearing friction within the control. The lack of a signal
strength meter can be compensated for by measuring the valve currents, but
with the IF gain backed off, there is not always a large movement with a
signal. An S meter position would be helpful. It only has 110 VAC and 220
VAC input, a 240 VAC setting would be beneficial to this country. When
being removed from the case, be careful as there is mains voltage on the fuse
directly in the centre bottom of the front panel. Similarly the meter has
exposed terminals with HT on them. None of these are really serious shortcomings.
PERFORMANCE
It is a beautiful receiver, very easy to use, and very sensitive. There
is so much gain, that when receiving SSB or CW signals, there is an annoying
crack at the beginning of every morse letter or SSB syllable, until the AGC
reduces the gain. To avoid this, I run the AF gain on full, and use the
IF gain control to set the output volume. It is easy to resolve SSB
signals, just set the BFO control 15 degrees to the left or right, (depending
on the sideband), and use the main tuning knob. It was never intended to
resolve SSB signals but it does easily. The receiver is extremely stable,
as there is a voltage regulator for the oscillator HT, and a barretter current
regulator for the oscillator heater. The other day, I was listening on
the 40 meter band to a UK amateur, talking to a Spaniard, a New Zealander,
and a Russian. Very nice, a pleasure to use.
REFERENCES
Red Ears, Soviet Professional Tube Receivers 1945 - 1970 Years, by
V.I. Shapkin, Moscow AVICO - Press 2003, ISBN 5-86309-070-7
Volna-K, an Unusual Russian Maritime Receiver, by Michael O'Beirne,
G8MOB,
page 8 -17, Radio Bygones No.74, Christmas 2001
CIRCUIT1 (88 kb)
CIRCUIT2 (84 Kb)
MANUAL (description) (2.8 Mb)
MANUAL (parts, wiring, circuit)
(2.6 Mb)
INTERNAL VIEWS
Figure 4. Left Hand View (coil covers removed from second IF)
Figure 5. Right Hand View
Top: mixer, RF, calibrator
Centre: turret
Bottom: first IF
Figure 6. Rear View
Top left: mixer, RF, calibrator
Bottom left: first IF
Top right: power supply
Bottom right: second IF
Centre top: optical scale and tuning capacitor
Centre bottom: turret
Figure 7. Speaker
Figure 8. Top View
Left: power supply
Centre: optical scale, tuning capacitor
Right: mixer, RF amplifier, calibrator
Figure 9. Bottom View (turret and cast chassis)
Copyright
Ray Robinson VK2ILV
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