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UHER 4000 Report
Open reel tape recorder

The Report 4000 was a series of portable open-reel magnetic-tape audio recorders, introduced by UHER in München (Germany) in 1961. It was one of the first truely portable fully transistorised recorders that dominated the professional (broadcast) market for many years. Numerious variants of this recorder exist, and it was also used by law enforcement agencies and in espionage trade.
The machine measures 270 x 215 x 85 mm and weights 3 kg. It is used with two open reels with a diameter of 13 cm (5 inch) and has two mono audio tracks. It offers four speeds for recording and play-back: 2.4, 4.75, 9.5 and 19 cm/s, selectable with a knob at the front top/right.

The Report 4000 is powered by five 1.5V D-size batteries, that are installed in a compartment that can be accessed via the removable bottom panel. Alternatively the unit can be powered by an external mains transformer, or an internal one that is fitted inside the battery holder.
UHER 4000 Report-S

Due to its excellent price/performance ratio, the UHER 4000 recorders were heavily used in the broadcast and film industry as an affordable alternative to Nagra. The first model of the 4000-range was introduced in 1961 and the machine was in production in various incarnations until 1966, when it was succeeded by the two-track 4200 and eventually by the 4-track 4400. The machine shown here was purchased by the previous owner in 1965 for DM 450 (EUR 225) 1 [1].
  1. Conversion to EURO is made without taking inflation into account. The machine was bought with the internal PSU (DM 63) and an accu pack (DM 35) on 17 February 1965 for a total of DM 548.

UHER 4000 Report-S Front panel Connections at the right side Front view with it lid open UHER 4000 Report-S with tape UHER 4000 Report-S with EDLB Operating the UHER 4000 Report from within the leather bag
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UHER 4000 Report-S
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Front panel
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Connections at the right side
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Front view with it lid open
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UHER 4000 Report-S with tape
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UHER 4000 Report-S with EDLB
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Operating the UHER 4000 Report from within the leather bag

The diagram below gives an overview of the controls and connections on the UHER 4000 Report S. Batteries are installed at the bottom. Alternatively, an internal power supply unit (PSU) can be installed in their place. In addition, an external PSU can be connected to the Accessory socket at the right side. The machine is loaded with a suitable audio tape, using 13 cm (5") spools.

The unit is powered by selecting one of the four speeds with the 'gear' type selector at the top right of the front panel. In the upper position of this selector, the machine is turned OFF. The speed selector can be locked in any position by turning its knob by 90 degrees. All tape controls are at the front right of the top surface, with the PAUSE switch acting as start/stop during a recording or playback session. Note that this button has to be released by pulling it up.

Both the volume and the tone control have an embedded switch that is activated by pulling the knob towards you. Pulling the volume knob will switch the meter from showing the recording level to the current battery level. Pulling out the tone knob turns on the meter illumination.
Front panel Connections at the right side Front view with it lid open UHER 4000 Report-S with tape Locking the speed selector Lowest speed (2.4 cm/s) selected 9.5 cm/s selected Turning OFF the machine
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Front panel
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Connections at the right side
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Front view with it lid open
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UHER 4000 Report-S with tape
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Locking the speed selector
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Lowest speed (2.4 cm/s) selected
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9.5 cm/s selected
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Turning OFF the machine

Other uses
The UHER Report 4000 was very popular with broadcast reporters, who were able to carry the recorder over shoulder during an interview, using one of the special leather carrying bags. The device was also used during criminal investigations, for example for tapping phone lines and for recording interrogations, or for covertly recording an important conversation in a room.
In the hands of Czechoslovakian secret services, such as the StB and Správa 1, the UHER was used as part of a so-called Electronic Dead Letter Box, or EDLB [2]. A secret agent who wanted to pass a message to his handler, would record a spoken message onto his UHER at the lowest possible speed (2.4 cm/s). A small transmitter was then connected to the right side of his recorder and also to the existing radio antenna of his car.

He then drove his car to a predetermined place and, whilst driving through the area, play back his message at the highest speed (19 cm/s).
Czechoslovakian Electronic Dead Letter Box. Click for further information.

Another recorder, hidden in the area, automatically recorded the message at the highest speed (19 cm/s). The message was later collected by the handler, either physically (by collecting the tape) or automatically in another drive-by. The advantage of this method was that the agent and his handler no longer had to meet physically. It reduced the risk of being observed and caught.
Later versions of the recorder, such as the UHER Report 4400, were sometimes customised for specific purposes, such as wire-tapping, phone logging and legal or criminal investigations.

One example is the Trevisan RT-2000 shown in the image on the right. It is a 4-channel real time audio recorder with a built-in real-time clock (RTC) and a thermal printer. It was mainly used on phone taps, in which case it provided the necessary legal evidence by recording (and printing) the current time and day, but also the phone number that was dialled by the subject.
Radio Trevisan RT-2000 multi-channel recorder. Click for further information.

The RT-2000 was based on the chassis of the UHER Report 4400, but all the internal electronics were replaced by Radio Trevisan. In addition, a completely new front panel was added, with room for some new controls, a wide red LED display and the thermal printer (bulging out at the left).

 More about the Czech dead letter box
 More about the Trevisan RT-2000
Carrying bags
For carrying the UHER Report 4000 around, a number of options were available. First of al, a leather or canvas strap could be attached to the two pins at both sides, close to the front panel.

In addition, a selection of leather carrying bags was available in black or brown, such as the one shown in the image on the right. The recorder can be operated from within the bag, and even the tape is accessible through a flap at the top.
Operating the UHER 4000 Report from within the leather bag

The Report 4000 is very service friendly for its age. The interor can be accessed simply by loosening the large kurled bolt at the bottom and removing the botton panel. Next, remove the orange carton by releasing the four bolts that keep it in place. The interior is now visible.
The amplifier board at the left is hinged and can be swung away after loosening a supporting post at the right (on top of the large flywheel assembly at the center). A few smaller PCBs are present with additional circuits, such as the audio amplifier and the motor control circuit.

Note the rather 'messy' circuit around the motor, where a small PCB is fitted to the chassis, with several of its components 'dangling in the air'. Despite this, the recorder is well constructed, both mechanically and electrically, and after 50 years, the one shown here still works a treat.

When restoring an old UHER 4000 recorder, one of the first things to check are the rubber belts. In some machines the rubber may have become 'liquid' or may have desintegrated completely. But even if the belts seem fine, they will probably need to be replaced after so many service years.

The 4000 Report-S has two different belts: one for driving the capstan and one for winding. Later models had three belts: the extra one was used to drive a counter that was fitted at the front panel. Replacing the belts is easy and good replacements are available from several sources [4]. Note that when replacing the capstan belt (left) the spring at the left of the assembly (marked above in red) should be removed temporarily. This can be tricky and requires a spring-hook.
Interior after removing the bottom panel Battery compartment Interior Interior Interior Releasing the retainer Messy circuit around the motor Interior
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Interior after removing the bottom panel
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Battery compartment
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Releasing the retainer
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Messy circuit around the motor
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Power source
  • 5 x 1.5V D-size battery
  • Rechargeable gel battery
  • Internal PSU (installed in battery compartment)
  • External PSU (fitted to accessory socket)
The UHER 4000 Report has three sockets at its right side. The middle one is for connection of an external speaker or a pair of headphones. The leftmost one is the line input/output and the rightmost one is the accessory socket. The pinout of the latter two sockets is as follows:
This is the (mono) phono/radio socket of the UHER recorder. It carries both input and output signals at line-level, using the standard 3-pin DIN layout. Pinout looking into the socket.
  1. Line in
  2. Ground (chassis)
  3. Line out
This is the accessory socket. It can be used for a remote control (foot switch) or an external 7.5V DC power source. Alternatively, the 7.5V line can also be used as an ouput (e.g. to power a peripheral device. Note that the recorder has the (+) terminal of the battery connected to the chassis. This means that the circuit is powered by -7.5V. Pinout looking into the socket.
  1. ?
  2. Audio (line out)
  3. Ground (7.5V battery +)
  4. Remote
  5. Power (7.5V battery -)
  6. Charge
  • Report 4000
  • Report 4000 S
  • Report 4000 IC
  • Report 4000 L
  • 1000
    Professional version of 4000
  • 4000
    2-track mono (later 4-track mono)
  • 4200
    2-track stereo (tape used in one direction)
  • 4400
    4-track stereo (double sided, also usable as 4-track mono)
  1. UHER, UHER 4000/4200/4400 Report Monitor, Service Handbook
    Without circuit diagrams. Date unknown. 1

  2. UHER, UHER 4000 Report-L, Model 4200 and 4400 Supplement
    With full circuit diagram. Date unknown. 1

  3. UHER, UHER 4000 Report-L and Report-S, Parts List
    Date unknown. 1

  4. UHER, UHER 4000 Report-L, Circuit Diagram
    Date unknown. 1

  5. UHER, UHER 4000/4200/4400 Report-IC and Stereo IC, Service Manual
    Complete with circuit diagrams. Date unknown. 1

  6. UHER, UHER 4000 Report IC, Circuit Diagram
    Date unknown. 1

  1. Via website HiFi Engine www.hifiengine.com

  1. Elektro-Export Aksur, Original invoice for Uher 4000-S
    Frankfurt am Main. 17 February 1965.

  2. Anonymous, Use of UHER Report 4000 by Czechoslovakian secret services
    Interview by Crypto Museum, June 2015.

  3. UHER Report 4000 IC, Technical description with circuit diagram
    March 1963. Website HiFi Engine. Retrieved April 2015.

  4. Erwin Bosch Trading, UHER 4000/4200/4400 Report - replacement belts
    Via eBay. Received August 2015.

Further information

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Crypto Museum. Created: Friday 21 August 2015. Last changed: Tuesday, 13 June 2017 - 18:06 CET.
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