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Receivers
  
ICF-PRO70   ICF-PRO80
Portable short-wave receiver

The ICF-PRO70 and the ICF-PRO80 are portable solid-state LW, MW, SW and FM receivers, also known as travel receivers, made by Sony around 1987. Although they were commercially available on the civil market, they were often used by spies and agents for reception of Numbers Stations.

The receiver has the shape of a handheld radio, and has controls at the front and at the top. A relatively large high-quality speaker is present at the bottom of the front side. User interaction is via the keyboard and the liquid crystal display (LCD), both of which are placed at the front.

Other controls, such as squelch, volume and power are at the top panel, which also holds a socket for connection of the telescopic antenna that was supplied with the kit. Note that on the PRO70, the antenna has to be mounted in the socket before the receiver can be switched on. 1
  
Sony ICF-PRO70

This is caused by a power switch that is embedded in the antenna socket. This switch is omitted from the PRO80, which features a normal TNC socket and therefore allows the connection of an external antenna. The ICF-PRO70 was a popular receiver for short wave (SW) listeners during the mid-1980s, although German customers faced restrictions in frequency range - imposed by the German authorities - as a result of which many amateurs bought their PRO70 receiver elsewhere.

The ICF-PRO80 did not have these restrictions and also covered the VHF-H band, by inserting a frequency converter between the antenna and the receiver. Needless to say that the receiver was also suitable for Cold War spies and agents for the reception of the mysterious numbers stations.

  1. On a later variant of the PRO70, the proprietary socket was replaced by a standard TNC socket.

Sony ICF-PRO70 Sony ICF-PRO70 Sony ICF-PRO70 Battery Sony ICF-PRO70 with antenna Controls at the top Telescopic antenna Knee joint
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Sony ICF-PRO70
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Sony ICF-PRO70
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Sony ICF-PRO70
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Battery
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Sony ICF-PRO70 with antenna
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Controls at the top
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Telescopic antenna
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Knee joint

Controls
The diagram below provides a quick overview of the controls and connections of the ICF-PRO70 and PRO80. The large and clear keypad at the front is used for entering frequencies directly and for controlling the scanning features. Visual feedback is provided by a clear LCD display that is located above the keyboard. The receiver is turned on by mounting the original yellow antenna in the antenna socket and pressing the recessed green power button at the left of the top panel.


Apart from the power switch, the top panel also holds the volume and squelch control, both of which can be depressed. When the volume control is depressed, a hi-cut tone filter is enabled. Pressing the squelch control enables auto-squelch. At the far right is a 4-position memory bank selector, with a fine tuning knob at the center. Power is provided by four 1.5V AA-size penlight batteries, installed in a battery pack at the rear, or by an external 6V DC battery source or PSU.

ICF-PRO70 Controls at the top Top panel Battery Display of the ICF-PRO80 External 6V DC input and light button PRO70, PRO80 and AIR-7 ICF-PRO70 with accessories
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ICF-PRO70
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Controls at the top
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Top panel
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Battery
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Display of the ICF-PRO80
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External 6V DC input and light button
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PRO70, PRO80 and AIR-7
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ICF-PRO70 with accessories

PRO70, PRO80 and AIR-7

Models
  • ICF-PRO70
    This is the original travel receiver described above. The design is based on the Sony AIR-7 (see below) and it was available in three different versions in order to meet the restrictions of the radio monitoring services of certain countries, in particular Germany's FTZ. The PRO70 had a proprietary antenna socket, but later units were fitted with a TNC socket.

  • ICF-PRO80
    This is basically the same receiver as the ICF-PRO70, but with the addition of the FRQ-80 Frequency Converter, that extends the frequency range with the VHF-H band (115.5-223 MHz). This includes the 2m amateur band (144-146 MHz) and the maritime VHF band. The PRO-80 was fitted with a standard TNC antenna socket, and has an extra (hidden) switch. 1

  • AIR-7
    This is a portable scanning receiver, specifically designed for reception of the AIR bands. It was released in 1985 and can also receive the FM broadcast band, plus the LW and MW bands, and part of the SW band (up to 2194 kHz). A standard BNC antenna socket is available. The same enclosure was later used with the ICF-PRO70 and ICF-PRO80 [2].
  1. An extra switch inside the battery compartment is used to enable the FRQ80 frequency converter.

Versions
Model Frequency Remark
ICF-PRO70 Type 1 150 kHz - 108 MHz Export version   
ICF-PRO70 Type 2 150 kHz - 29.995 MHz, 87.6 - 108 MHz European version
ICF-PRO70 Type 3 150 kHz - 26.100 MHz, 87.6 - 108 MHz German version
ICF-PRO80 150 kHz - 108 MHz + 115.15 - 223 MHz with Frequency Converter
ICF-PRO80
The ICF-PRO80 is nearly identical to the PRO70, but has an extended frequency range, which is available by inserting a Frequency Converter between the antenna socket and the antenna.

The image on the right shows the ICF-PRO80 with the FRQ-80 Frequency Converter and the original telescopic antenna. Note that the connector of this antenna is different from the (similarly looking) antenna of the PRO70. The two are not interchangeable.
  
ICF-PRO80 with Frequency Converter and antenna

ICF-PRO80 with Frequency Converter and antenna Display of the ICF-PRO80 Controls at the top With converter installed With converter installed Frequency converter installed Telescopic antenna Knee joint
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ICF-PRO80 with Frequency Converter and antenna
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Display of the ICF-PRO80
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Controls at the top
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With converter installed
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With converter installed
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Frequency converter installed
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Telescopic antenna
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Knee joint

AIR-7   AIR-8
The AIR-7 (and AIR-8) predates the PRO70 and PRO80 models. It was introduced in 1985 and is built with older technology 1 which is why in some respects these devices last much longer.

The AIR-7 receiver covers the AM broadcast band (150-2194 kHz), the FM broadcast band (76-108 MHz), the air band (108-137 MHz) and the 2 meter VHF-H band (144-175 MHz). The AIR-8 offers the same frequency bands, but with the upper limit of the air band at 138 MHz [2].

The following bands are available:
  
AIR-7

Band Frequency Modulation Remark
AM 150 - 2194 kHz AM wideband -
FM 76 - 108 MHz FM wideband 87.6-108 on some versions
AIR 108 - 137 MHz AM narrowband AIR-8: 108-138 MHz
PSB 144 - 175 MHz FM narrowband Not on all versions 2

Note that the 2-meter Public Service Band (PSB) is not available on all models. You can find out which version you are dealing with, by checking the band selector at the top right. If it has four positions, you have the full four-band version. Note that on some variants, the band selector has four positions although only three are visible on the top panel. In that case the PSB is hidden. 2

  1. The electronics of the AIR-7 are built on pertinax PCBs, whilst the PCBs of the PRO70 are made of (better) epoxy. The electrolytic capacitors of the AIR-7 are of the older conventional type and do not suffer from the leakage problems that affects all electrolytic capacitors of the PRO70 and PRO80.  More
  2. A three-band version can easily be converted into a four-band version by removing a small screw from the frame, just behind the band selector knob. This screw simply limits the number of steps of the selector.

AIR-7 AIR-7 with 'rubber-duck' helical antenna AIR-7 display Three band version Four band version Interior of the AIR-7 AIR-7 control board Removed the screw from the frame (near the selector) to enable the 4th band
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AIR-7
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AIR-7 with 'rubber-duck' helical antenna
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AIR-7 display
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Three band version
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Four band version
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Interior of the AIR-7
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AIR-7 control board
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Removed the screw from the frame (near the selector) to enable the 4th band



ICF-PRO70 with accessories

Accessories
Telescopic antenna Internal batteries Miniture ear piece Soft carrying case Shoulder strap Frequency converter (ICF-PRO80 only)
Antenna
Each receiver was supplied with a telescopic antenna that is encapsulated in bright yellow rubber, embossed with the Sony logo. The antenna has a knee joint that allows it to be adjusted for the best possible reception without moving the radio around.

At the bottom is a screw-connector that fits the antenna socket of the radio. Note that the socket of the PRO70 is different from the one on the PRO80. The socket of the PRO70 has a built-in power switch, which is omitted from the PRO80.
  
Telescopic antenna

Batteries
The receiver can be powered by internal dry batteries, that are installed as a block at the rear. The block can easily be removed and holds four 1.5V AA-size penlight cells, as shown here.

It is also possible to power the radio from an external 6V DC source, that can be connected to the power socket at the right side.

Note that the PRO70 can only be switched on when the antenna is installed. This is caused by a switch in the base of the antenna socket.
  
Battery

Earphone
The ICF-PRO70 was usually supplied with a miniature earphone, such as the one shown in the image on the right. It has a 50 cm cable with a 3.5 mm mono jack at the end, that mates with the earphone socket on the top panel.

The receiver can be used with virtual any type of earpiece that has a similar connector. When it is plugged-in, the internal speaker is switched off.
  

Carrying case
To protect the radio against dust and rain, the soft carrying case shown in the image on the right was supplied with each unit. It has a large transparent section at the front through which the keyboard and display are visible. The flap at the top is held in place by a Velcro strip.

Although this case offers some protection, most users found it more comfortable to operate the radio outside the carrying case.
  
ICF-PRO70/80 in carrying case

Shoulder strap
Apart from the soft carrying case shown above, each radio was also supplied with an adjustable shoulder strap that could be fitted to the metal brackets at the sides of the radio (near the top).

This way, the shoulder strap remains attached to the radio, even when the soft carrying case is not used. If you don't want to use the shoulder strap, the metal brackets can easily be removed.
  

Frequency Converter   ICF-PRO80 only
The frequency range of the ICF-PRO80 can optionally be expanded with the VHF-H band, which runs from 115.5-223 MHz, by inserting the FRQ-80 Frequency Converter between the antenna and the antenna socket, as shown in the image on the right.

Note that the frequency converter is powered by two internal 1.5V AA-size batteries. When using the converter, a hidden switch inside the battery compartment has to be toggled in order to enable the extended frequency range.
  
Frequency converter installed

ICF-PRO70 with carrying case ICF-PRO70/80 in carrying case Frequency converter (115.5-223 MHz) Frequency converter installed Battery block Battery block Slide out the sub-assembly
Receiver with shoulder strap Telescopic antenna Knee joint
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ICF-PRO70 with carrying case
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ICF-PRO70/80 in carrying case
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Frequency converter (115.5-223 MHz)
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Frequency converter installed
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Battery block
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Battery block
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Slide out the sub-assembly
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Receiver with shoulder strap
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Telescopic antenna
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Knee joint





Interior
Getting access to the interior of the ICF-PRO70 and ICF-PRO80 is easy and requires the removal of six screws: two at the sides (holding the brackets for the shoulder strap), two at the rear (close to the top) and two in the battery compartment (visible after removing the battery pack).

Once the screws are removed, the rear plastic black case shell can be taken off. When doing this, you may have to desolder a capacitor that is connected to one of the terminals of the battery compartment. Note that the knobs do not have to be removed from the top panel adjustments. They are better left in place to avoid stress on the potentiometers when refitting them again.

The receiver is mounted to the front half of the case, by means of two screws, one at the top (close to the top panel) and one at the center of the battery area (just below the ferrite antenna).
  
ICF-PRO70 interior

After removing these two screws, the metal frame with the PCBs can be lifted from the case shell. The frame contains three PCBs, each of which has components at both sides. Unlike the AIR-7, which is mainly built with conventional components, the PRO70 is largely built with SMD parts.

The smallest board is the actual receiver (the RF board). It is visible in the image above. At the other side of the stack is the control board that holds the keyboard. In between these two boards is the audio board. Remove two screws from the sides of the metal frame to expose the audio board, as illustrated in the image on the right.

Note that there is a lot of wiring between the two boards and to other parts of the radio. All wiring is fixed in place and cannot be removed easily. Be careful not to damage any of the wires when moving the PCBs around as part of a repair job.
  
Audio board

The potentiometers for volume and squelch control, are mounted on a small carrier board that is fitted to the frame at the bottom of the RF board. It is wired to the audio board. With equipment of this age (30+ years), it is likely that a repair is necessary in order to bring it back to life again. In fact, due to the use of bad quality electrolytic capacitors in the design, it is nearly certain that the receiver no longer works by now. Suitable repair directions are provided in the section below.

ICF-PRO70 interior Interior RF unit RF board with original (bad quality) electrolytic capacitors Antenna socket with built-in power switch Audio board exposed Audio board AIR-7 interior
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ICF-PRO70 interior
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Interior
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RF unit
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RF board with original (bad quality) electrolytic capacitors
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Antenna socket with built-in power switch
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Audio board exposed
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Audio board
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AIR-7 interior

Restoration
Bringing an old ICF-PRO70 back to life can be difficult. Like many other Sony devices, the PRO70 seems to have a built-in lifetime, causing the device to stop working after a number of years. In this case, the limited lifetime is caused by a large number of bad quality electrolytic capacitors.

The problem is typical for electronic equipment that is built in the 1980s and 1990s and is also encountered with other brands of the era. Due to a problem with the chemical substance (the so-called electrolyte), they have a tendency to start leaking after a number of years. The electrolyte then disappears into the radio and the capacitors lose their capacity and, hence, their function.

With the ICF-PRO70, all electrolytic capacitors are affected by this problem. The result will be the absence of an audio signal or, in some cases, a very soft or unstable or cracking audio signal.
  
Replaced capacitors in the RF unit

The problem can be fixed by replacing all electolytic capacitors, both on the RF board and on the audio board. Even if your radio appears work fine, it is recommend to replace these capacitors as they will eventually leak chemicals into the radio, which might cause (irreparable) damage. The image above shows part of the RF board on which the electrolytic capacitors have been swapped. Note that we have replaced some of them by modern high-quality long-life ceramic alternatives.

And whilst the radio is open, it might be good to consider the removal of the power switch that is embedded 1 in the antenna socket of the PRO70. This power switch is connected in series with the radio's power line. As a result, the radio can not be switched on when the antenna is dismounted.

Although this switch was probably added for good reasons — the radio can not be turned on accidently during transport — in practice it was often a nuisance. Furthermore, it disallows the connection of an external antenna. Note that this embedded switch is not present on the PRO80.
  
Antenna socket with built-in power switch

The function of the switch in the antenna socket can easily be bypassed by desoldering the red and brown wires from the antenna socket and soldering them together. Use proper insulation to avoid short-cuts. And whilst you are at it, you might want to swap the antenna socket for a more common BNC socket, so that it becomes possible to connect an external antenna. Note that if you do this, the original telescopic antenna can no longer be used, as it has a proprietary connector.

Another problem that affects many AIR-7, PRO-70 and PRO-80 receivers, is that the potentio­meters of the volume and squelch controls can be worn out. Although these potentiometers are high-quality types made by Alps, they are likely to be affected by many years of intensive use.

Finding identical replacement potentiometers will be next to impossible after all these years, but it might be possible to find alternatives that fit in the available space. Furthermore it might be possible — with the right tools and a lot of patience — to repair the existing worn-out ones.
  
Volume and squelch potentiometers

This is done by carefully milling off the rear ends of the two metal rods that keep the potentio­meter together. After removing the two rods, the green plastic enclosure can be taken apart. Be careful not to lose any of the parts. The problem is that the center contact (i.e. the slider) is no longer attached to the plastic disc that rotates it. Put it back in place and melt the plastic some­what (using a soldering iron) to affix it again. Then carefully reassemble the potentiometer and push the rods back in, to keep the parts together. Use a piece of mylar tape to strengthen the assembly, and solder it back onto the carrier board. The controls should now work as expected.

  1. According to Sony, a later variant of the PRO-70 was equipped with an TNC antenna socket, just like the PRO-80, allowing the connection of an external antenna by using a (supplied) BNC adapter.

RF board with original (bad quality) electrolytic capacitors Capacitors removed from the board (and board cleaned) Replaced capacitors in the RF unit Restored audio board Antenna socket with built-in power switch Another view of the antenna socket of the PRO70 Connecting the read and brown wires, in order to bypass the power switch in the antenna socket Volume and squelch potentiometers
Potentiometer taken apart Removing the rods Removing the carbon track Dislocated slider inside the potentiometer Reseating the slider Fixating the slider Repaired slider Repaired potentiometer
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RF board with original (bad quality) electrolytic capacitors
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Capacitors removed from the board (and board cleaned)
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Replaced capacitors in the RF unit
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Restored audio board
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Antenna socket with built-in power switch
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Another view of the antenna socket of the PRO70
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Connecting the read and brown wires, in order to bypass the power switch in the antenna socket
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Volume and squelch potentiometers
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Potentiometer taken apart
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Removing the rods
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Removing the carbon track
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Dislocated slider inside the potentiometer
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Reseating the slider
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Fixating the slider
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Repaired slider
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Repaired potentiometer

Connections
Power socket
The receiver can be powered by internal batteries (installed at the rear), but also by an external 6V DC power source that can be connected to the power socket at the right side. Note that the (+) terminal is connected to the sleeve, which is different from most other domestic equipment.



Technical specifications
  • Bands
    LW, MW, SW, VHF
  • System
    Dual conversion superheterodyne
  • Frequency
     see versions
  • Antenna
    Built-in ferrite, external telescopic, TNC socket
  • Audio
    400 mW
  • Output
    Earphone jack (8Ω)
  • Recording
    Mini jack, 0.775 mV (-60 dB), 1 kΩ
  • Power
    4 x 1.5V AA battery, or external 6V DC source
  • Life
    Approx. 10 hours with standard batteries
  • Dimensions
    182 x 90 x 50 mm
  • Weight
    650 g
Channel Spacing ICF-PRO80
  • 115.150 - 115.528 MHz
    3 kHz
  • 115.531 - 116.602 MHz
    9 kHz (optionally 10 kHz)
  • 116.605 - 164.995 MHz
    5 kHz
  • 165.000 - 190.995 MHz
    5 kHz (50 kHz in FM)
  • 191.000 - 223.000 MHz
    50 kHz
Standard accessories
Optional accessories
  • AC power adapter AC-D4
  • Rechargeable battery pack BP-23
  • Car battery cord DCC-127A, DCC-120 or DCC-240
  • Battery case EBP-6
  • Connecting cord RK-69A
  • VHF antenna AN-3
Documentation
  1. ICF-PRO70 / ICF-PRO80, Operating Instructions
    Sony Corporation. 3-990-095-12. 1987.

  2. ICF-PRO70/PRO80, Service Manual (revised)
    Sony Corporation. 9-952-864-82. September 1999.
References
  1. Martin Bösch, Sony ICF-PRO70 Scanner Receiver
    Retrieved October 2017.

  2. Martin Bösch, Sony Air Band Receiver AIR-7 / AIR-8
    Retrieved October 2017.

  3. Radio Museum, Sony AIR-7
    Retrieved Actober 2017.
Further information
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Crypto Museum. Created: Tuesday 03 October 2017. Last changed: Friday, 06 October 2017 - 08:23 CET.
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