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Barlow-Wadley XCR-30
Portable short-wave receiver

XCR-30 was a portable transistorised short-wave (SW) receiver, introduced in 1969 by Barlow-Wadley in New Germany (South Africa). The device has an extremely wide frequency span of 500 kHz to 30 MHz – divided over 30 linear 1 MHz segments – which it owes to the so-called Wadley Loop, an invention of Dr. Trevor Wadley that was also used in Racal receivers like the RA-17 [3].

Although the receiver has the appearance of a cheap Japanese portable radio of the 1970s, it is in fact a well-designed, well-built device in a shielded strong (partly die-cast) metal case.

In the 1970s, the XCR-30 was a highly desired receiver amongst radio amateurs, many of whom couldn't afford the relatively high initial price of US$ 269. Over the years, several versions and variants of the receiver appeared on the market, such as one with a complementary FM broadcast receiver mounted at the top, and a rather rare one in a dark green (military-looking) enclosure.
  
Barlow-Wadley XCR-30 with TR-801 FM broadcast option fitted, and frequency scale up

The receiver is suitable for the reception of AM, LSB and USB narrowband signals. The FM version – featured here – is also suitable for the reception of wideband signals in the 87.5 to 101 MHz range. Although its tuning principle was revolutionary at the time of the introduction, it lost its popularity when the Phased Locked Loop (PLL) and the Frequency Synthesizer were introduced.

Due to the unobtrusive appearance of the radio, its wide frequency coverage, and the fact that it could be purchased from radio stores in the USA and in Europe without attracting any attention, the XCR-30 was also used during the Cold War by intelligence services from both sides of the Iron Curtain, for example for the reception of messages via the One-Way Voice Link (OWVL). 1

The radio was first introduced in 1969 2 for a price of US$ 269 and was in production until 1981. In the UK, it was distributed by the Radio Shack for GBP 146, with the optional TR-801 FM tuner separately available for GBP 25 [6]. In Germany, the XCR-30 Mark 2 was sold in 1974 for DM 740.

  1. Also known as Numbers Stations.
  2. Initial introduction in South Africa. Some countries followed later.

Barlow-Wadley XCR-30
Barlow-Wadley XCR-30 with TR-801 FM broadcast option fitted, and frequency scale up
Front view
Front view
Rear view
Frequency scale
Tuning scale
A
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A
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Barlow-Wadley XCR-30
A
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Barlow-Wadley XCR-30 with TR-801 FM broadcast option fitted, and frequency scale up
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Front view
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Front view
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Rear view
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Frequency scale
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Tuning scale

Features
The diagram below provides a quick overview of the features of the Barlow-Wadley XCR-30 Mk2, which – in this case – has the optional TR-801 FM broadcast band receiver fitted at the top, which raises the frequency table — collapsed here — and the carrying handle by several centimetres.

Click to see more

The actual shortwave receiver – the lower part – has two tuning knobs and two frequency scales. At the left is the setting for the MHz, whilst the setting for the kHz is at the right. This way the radio provides 30 linear segements of 1 MHz each, with a tuning accuracy of approx. 5 kHz. Fine tuning is possible with the small knob below the S-meter, whilst for the reception of SSB (LSB or USB) a separate clarifier control is present. The desired MODE is selected at the bottom right.

FM broadcast band option
Tuning scale
Tuning scale
Tuning the MHz dial
Telescopic antenna
Antenna socket
Frequency scale
External power socket and headphones socket
B
×
B
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FM broadcast band option
B
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Tuning scale
B
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Tuning scale
B
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Tuning the MHz dial
B
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Telescopic antenna
B
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Antenna socket
B
7 / 8
Frequency scale
B
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External power socket and headphones socket

Versions
  • XCR-30
    This is the original model, introduced in 1969, which is built around 18 transistors. It is likely that this version was never sold in Europe. It was succeeded in 1973 by the XCR-30 Mark 2, but the differences between the two versions are unclear.

  • XCR-30 Mark 2
    This model was probably introduced in 1970. It is nearly identical to the original version, but may have been improved, although it is currently unclear what the improvements are. The XCR-30 receiver featured on this page, is of this type. Around June 1974, the circuit was further improved with an audio amplifier built around a TAA611 integrated circuit (IC) and a new design for the 1 MHz harmonic generator. The improved version contains one IC and 14 transistors, some of which are slightly different from the original ones.

  • TR-801
    Optional tuner for the 87.5 to 101 MHz FM broadcast band, that can be mounted on top of an existing XCR-30 Mark 2 receiver. It was available as an add-on kit for GBP 25 (UK, 1975) [6]. It is present on the XCR-30 receiver featured here.

  • XCR-30 FM Mark II
    This model is largely identical to the XCR-30 Mark 2, but comes with the TR-801 FM broadcast receiver (87.5 to 101 MHz) already installed. The TR-801 is completely separate from the rest of the radio and was also available separately as the TR-801 add on (see above) [6]. This model was available in Germany in 1974 for a price of DM 740.
Block diagram
Below is the block diagram of the XCR-30 radio. At the top left is the antenna input circuit, which comprises a novel pre-selector with hand-operated permeability tuning, an RF pre-amplifier and a low-pass filter. This signal is then mixed (X1) with the free-running 45.5 - 75.5 MHz output of the MHz-VFO, which forms one half of the Wadley Loop, resulting in an IF1 of 44.5 to 45.5 MHz.

The same 45.5 - 75.5 MHz signal from the MHz-VFO is mixed (X2) in the other half of the Wadley Loop, with the output of an harmonic generator that produces a series of signals between 3 and 33 MHz at 1 MHz intervals. Only the 42.5 MHz product of X2 is used, and is mixed (X3) with the IF1 signal from the first half of the Wadley Loop, resulting in a 1 MHz wide 2 - 3 MHz IF2 signal.

The rest of the circuit is bascially a regular heterodyne receiver. The 2-3 MHz IF-signal is mixed in X4 with the output of the free-running kHz-VFO, resulting in a 455 kHz IF3-signal, which is fed to an AM-detector and amplified to speaker level. For the reception of Single Side Band (SSB) signals (LSB, USB) and CW (morse), an adjustable Beat Frequency Oscillator (BFO) can be enabled.


This design is also known as a triple-conversion receiver with IF frequencies at 45 MHz, 2.5 MHz and 455 kHz. Note that this circuit has an inherent drift compensation: if the MHz-VFO drifts, the drift equally affects the output of X1 and X2, which is cancelled out in X3. As a result, the quality of the receiver is only determined by the stability and accuracy of the 1 MHz crystal oscillator.


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Interior
The interior of the XCR-30 can be accessed by loosening the two large bolts in upper corners of the rear panel, after which the hinged rear panel can be lowered, 1 as shown in the image above. A plastic battery holder for six 1.5V D-size battery cells, is mounted to the inside of this panel.

Inside the metal case is a large printed circuit board (PCB) with two large cut-outs, one for the speaker and one for the cylindrical tuning scales. The PCB holds all circuits, except for the 1 MHz harmonics generator, which is mounted at the other side of the PCB, behind the front panel.

The image on the right shows an early version of the XCR-30 Mk2, in which the output stage of the AF amplifier is built around two Germanium transistors. In June 1974 they were replaced by a TAA 611 integrated circuit (IC). At the same time the harmonic oscillator was altered (see below).
  
Open rear panel

The upper half of the PCB holds two variable frequency oscillators (VFOs). At the right is the main VFO that is used to select the MHz, resulting in an IF1 frequency around 45 MHz. This signal is mixed with the 42.5 MHz from the harmonic generator, resulting in an IF2 frequency around 2.5 MHz. This signal is then mixed with the 2.455-3.455 MHz signal from the kHz VFO, resulting in an IF3 frequency of 455 kHz, which is then passed to the detector and amplified to speaker level.

At the top right is the pre-selector which is further described below. It is adjusted in tandem with the MHz VFO. Although the sensitivity of the receiver is very good, the dynamic range is not. The pre-selector can not prevent overloading by signals in the same 1 MHz segment, and neither can the Automatic Gain Control (AGC), which only affects the IF3 stage and not the RF pre-amplifier.

  1. The rear panel can be removed completely, by opening it by just 5 mm and then pulling it upwards.

Barlow-Wadley XCR-30 with open rear panel
Interior, seen from the rear
Open rear panel
Interior
kHz tuning (left) and MHz tuning (right)
Pre-selector
IF-circuits
RF-circuits
Interior seen from the front (solder side)
1 MHz harmonic generator
BFO tuning and fine tuning
C
×
C
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Barlow-Wadley XCR-30 with open rear panel
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Interior, seen from the rear
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Open rear panel
C
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Interior
C
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kHz tuning (left) and MHz tuning (right)
C
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Pre-selector
C
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IF-circuits
C
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RF-circuits
C
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Interior seen from the front (solder side)
C
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1 MHz harmonic generator
C
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BFO tuning and fine tuning

Pre-selector
The receiver has a beautifully constructed pre-selection filter that is located between the antenna input circuit and the RF pre-amplifier. It consist of a 1st order parallel tuned circuit, of which the capacitor (C) is tuned in tandem with the MHz-VFO. The inductor (L) has a ferrite core that moves with the ANTENNA TRIM knob at the front panel. In fact, the inductor consists of three separate windings, one for each frequency range: (1) 0.5 - 2 MHz, (2) 2 - 8 MHz and (3) 8 - 30 MHz.

Construction of the knob-operated pre-selector inductor

The image above shows the construction. At the bottom centre is the ANTENNA TRIM knob, which operates a cam-wheel. The cam has two sloped edges, each of which can engange a microswitch. Depending on the position (angle) of the TRIM knob, either or both microswitches are activated.

Harmonic generator
The harmonic generator is implemented as a separate PCB, which is mounted to the solder side of the main PCB. It can only be accessed from the front of the device, for which the knobs and the front panel have to be removed. In the original design, it consisted of a 1 MHz crystal oscillator, of which the output was filtered and applied to an AA112 diode (which causes the harmonics to be generated) and then passed through a 4-stage PI-filter, before applying it to mixer X2.

Old version of the 1 MHz harmonic generator

Apparently this design caused problems in some receivers, as it was dropped around June 1974 [B]. In the improved design, a small transformer with just 3 windings is used as the non-linear element, by applying a 1 MHz signal with a level that is high enough to saturate its ferrite core. At the same time, the 4-stage filter was replaced by a single-stage long ferrite bead (ferrox core).

New version of the 1 MHz harmonic generator


Restoration
When we received the Barlow-Wadley XCR-30 featured here, it was not in good shape. Apart from being very dirty, its interior showed severe corrosion – especially at the bottom panel – which had clearly been caused by leaking batteries. Apparently it had been stored for a long time, without removing the old batteries. It demonstrates that batteries are the biggest enemy of a collector.

After removing the most obvious corrosion and cleaning the battery holder, the bottom panel was treated with Owatrol® , a substance that prevents further corrosion. The bottom panel was then covered with a thin piece of neoprene foam, after which the wiring was taped in place.

The image on the right shows the bottom panel of the radio and the battery holder, before the restoration. Although the battery holder is now functional again, it is better to demonstrate the radio in the future by means of an external power supply unit (PSU) or a mains AC adapter.
  
Corroded bottom panel caused by leaking batteries

After the initial restoration was completed, it was time to power the radio up. Although it received a local radio station in the FM broadcast band (87-106 MHz), the sound was heavily distorted. As the shortwave receiver exhibited the same problem, the root cause had to be in the AF amplifier.

A closer inpection of the AC175 (TR15) and the AC117 (TR16) in the final stage of the amplifier, revealed that the legs of these transistors were severely corroded and were partially missing, again caused by leaking batteries. It was decided to replace them by AC187/AC188 respectively.

As the caps and the legs of the two driver stages - BC108 (TR13) and BC262 (TR14) – were also heavily corroded, it was decided to replace them by a BC547 and BC557 respectively. This turned out to be a good decision, as the legs fell apart the moment TR13 and TR14 were desoldered.
  
Restored AF amplifier

As the front panel had to be removed in order to replace the transistors, it was decided to replace all electrolytic capacitors at the same time. They have a tendency to lose their capacity over time, and some of them showed signs of leakage and corrosion. The image above shows the result.

Further testing revealed an intermittent problem with the pre-scaler. When turning the ANTENNA TRIM knob, two switches at the circumference of a cam-wheel, select one of the three available tuning ranges (see above). Due to slack on the axle and wear on the tips of the microswithces, the switches sometimes didn't latch properly, resulting in the selection of the wrong range.

The problem was solved by re-adjusting the microswitches and placing them ~ 1 mm closer to the cam-wheel so that they were no longer missed when turning the ANTENNA TRIM knob.
  
Pre-selector

Furthermore, the tips of the switches – that had been flattened by wear – were rounded off again by means of a dental mill, to avoid excessive shear forces when catching the ramp of the cam-wheel. The pre-selector now correctly selects the desired frequency range again, which greatly improves the sensitivity of the receiver. In a final test we were able to receive radio amateurs around 3.5 and 7 MHz, and broadcast stations on 7.2 and 7.4 MHz and in several other bands.

Damage from leaking batteries
Corroded bottom panel caused by leaking batteries
Corrosion detail
Restored bottom panel and battery holder
Restored bottom panel detail
Restored AF amplifier
D
×
D
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Damage from leaking batteries
D
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Corroded bottom panel caused by leaking batteries
D
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Corrosion detail
D
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Restored bottom panel and battery holder
D
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Restored bottom panel detail
D
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Restored AF amplifier

So far, the following restoration work has been carried out:

  • Exterior cleaned thorougly
  • Exterior paint and artificial leather restored
  • Interior thoroughly cleaned
  • Corrosion from leaking batteries removed
  • Bottom plate restored and treated with Owatrol®
  • Frequency table restored
  • Transistors TR13, TR14, TR15 and TR16 replaced
  • All electrolytic capacitors replaced
  • Microswitces on the pre-selector cam-wheel re-adjusted
  • Speaker gasket replaced

ID Type Polarity Replacement Remark
TR13 BC108 NPN BC547 Note the odd placement of the pads
TR14 BC262 PNP BC557 Note the odd placement of the pads
TR15 AC175 NPN AC187, AC127  
TR16 AC117 PNP AC188, AC128  
Barlow & Wadley
The XCR-30 receiver was developed by Dr. T.K. Wadley, who had previously worked for the South African Council for Scientific and Industrial Research (CSIR) and had developed receivers for Racal in the UK. He is the inventor of the so-called Wadley Loop [7], which was also used in expensive professional contemporary Racal receivers, and in other equipment of the South African and British governments. The Wadley-Loop is still used today in the design of spectrum analyzers [5].

The XCR-30 was manufactured by the Barlows Group in South Africa — who also built domestic Sony and Matsushita (Panasonic) equipment under licence — at the Barlows Television Company plant in New Germany (Natal, South Africa). Upon its introduction (around 1970), the XCR-30 became an instant hit among radio amateurs all over the world. Despite the fact that approx. 20,000 units were produced, not many have survived. And the ones that did survive, are often damaged by leaking batteries. Nevertheless they occasionally turn up on auction sites like eBay.

Similar receivers
The Wadley Loop was used in the following receivers [8]:

  • Racal RA-17
  • Racal RA-117
  • Racal RA-217
  • Racal RA-1217
  • Racal RA-1218

  • General Dynamics R-1051
  • Barlow Wadley XCR-30
  • Drake SSR-1 1
  • Yaesu FRG-7 2
  • Sommerkamp FRG-7 2
  • Sears Communications Receiver 2
  • Realistic DX-300
  • Lowe SRX-30 1
  • Century 21 1
  • Standard C-6500 1
  1. Based on SSR-1 made in Japan.
  2. Based on FRG-7 made by Yaesu in Japan.

Last known address
  • Barlows Television Company
    Division of Barlows Manufacturing Company Limited
    29 Shepstone Road
    New Germany 3600
    South Africa
Connections
Power
At the left side of the XCR-30 are two sockets: a 3 mm jack socket for connection of the head­phones (bottom) and a universal power socket for connection of an external 6-12V power source (top). Note that the negative terminal should be connected to the centre contact, whilst the positive terminal should be connected to the sleeve. This is different from most other devices.



Specifications
  • Type
    Wadley-Loop (tripple-conversion)
  • Frequency
    500 kHz to 30 MHz
  • Clarifier
    ± 1.5 kHz
  • Accuracy
    < 5 Khz
  • Mode
    AM, LSB, USB, CW
  • Sensitivity
    ≤ 1µV for 50 mW
  • Selectivity
    6 kHz (AM), 3 kHz (SSB, CW)
  • IF
    (1) 45 MHz, (2) 2.5 MHz, (3) 455 kHz
  • Audio
    0.4 Watt
  • Response
    150 kHz to 3 kHz @ 3dB
  • Image
    Rejection ≥ 50 dB (≥ 60 dB on fixed images)
  • Antenna
    Telescopic or external (using antenna and ground terminals)
  • Transistors
    18 (from June 1974 onwards: 14 + 1 IC)
  • Power
    6 to 12 V DC (typically 9V)
  • Batteries
    6 x 1.5V D-size (9V)
  • Current
    20 mA (with no audio)
  • Dimensions
    292 × 190 × 98 mm
  • Weight
    4140 grams
  • Price
    US$ 267 (USA, 1969)
  • Quantity
    ~ 20,000
Documentation
  1. XCR-30 Operating Instructions
    Barlow-Wadley, November 1970.

  2. XCR-30 Mark II service manual 1
    Barlow Wadley, 31 July 1974.

  3. XCR-30 circuit diagram
    Barlows Television Company, 31 July 1974.

  4. A method to set the AGC
    H. Holden, 2018.

  5. TR-801, Installation and Operating Instructions
    Barlow-Wadley, October 1972.
  1. Obtained from www.manualslib.com.

Literature
  1. L. Foreman, Moderne Communicatie-Ontvangers (in Dutch) 1
    Radio Bulletin, October 1974, pp. 400-404.

  2. L. Foreman, De Barlow-Wadley XCR-30Mk2 (in Dutch) 1
    Radio Bulletin, April 1975, pp. 149-153.

  3. L. Foreman, De Barlow-Wadley XCR-30Mk2 (in Dutch) 1
    Radio Bulletin, May 1975, pp. 191-193.
  1. Obtained from NVHR library.

References
  1. Gerard's Radio Corner, 27. The Barlow-Wadley XCR-30 Shortwave receiver
    Retrieved September 2019.

  2. PA2OHH, The Barlow Wadley XCR-30 Shortwave receiver
    Retrieved September 2019.

  3. Lennart Benschop, The Wadley Loop
    Retrieved September 2019.

  4. Radio Museum, Barlow-Wadley
    Retrieved September 2019.

  5. Wikipedia, Trevor Wadley
    Retrieved September 2019.

  6. Radio Shack Ltd., Advert of Barlow Wadley's XCR-30 Mark 2
    Radio Communication, June 1975.

  7. Wikipedia, Wadley loop
    Retrieved October 2019.

  8. Brent Hilpert, Racal RA-17 & RM-117 Radio Receivers
    Retrieved October 2020.
Further information
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Crypto Museum. Created: Wednesday 18 September 2019. Last changed: Sunday, 11 October 2020 - 22:26 CET.
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