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Miniature direction finder
- under construction
PE-484 was a miniature body-wearable
radio direction finder (RDF) —
in German: Kleinstpeilempfänger — introduced in 1958 by
Telefunken in Ulm (Germany).
The device was intended for locating clandestine transmissions
and spy radio stations,
during the early part of the Cold War.
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The set consists of a body wearable miniature receiver
that is housed in an ergonomic bakelite enclosure, a
loop antenna that can be carried at the back
under the clothing, and a
field strength indicator disguised as a
regular wristwatch.
It was designed for unobtrusive – undercover – use.
The receiver cover the frequencies between 57 kHz and 20.6 MHz – with a
small gap between 443 and 498 kHz – divided over 10 frequency bands. Each band
required a specific cylindrical plug-in coil pack,
that also acted as the tuning scale. Audio is delivered to a
small earpiece.
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The PE-484 was first introduced in 1958, as a successor to the WWII
Gürtelpeiler.
It was initially built with miniature
valves (tubes), but over time the design was
improved several times, and the valves were gradually replaced by
modern transistors.
The final version – PE-484/5 – was a fully transistorised device.
The device was succeeded in 1989 by the completely redesigned
PE-484/9.
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All controls and connections are located at the front panel,
as shown in the diagram below. At the centre are four small 2-pin sockets —
typical for electronic hearing aids of the era — to which the antenna(s),
the headphones
and the field-strength indicator (i.e. the watch meter) are connected.
The small tear-shaped knob at the centre is used to switch the device
ON and select the desired modulation type (A1 or A3). The frequency
is adjusted with the tuning knob at the left. The large numbered dial at the
right is for setting the volume level. The small circular knob at the centre
is for switching ON the vertical reference antenna and adjusting its phase.
The two metal rods at the left and right sides accomodate a canvas belt,
by which the receiver can be carried on the body.
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The PE-484 was in production for many years, during which time the
exterior was never changed. Internally however, the designers gradually
made the transition from valves (tubes) to transistors, indicated by the
suffixes to the serial number. The first variant did not have a suffix.
In 1989, the line was replaced by the short-lived PE-484/9,
which had a completely redesigned enclosure.
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PE-484 Initial valve-based version PE-484/2 Hybrid version with valves and transistors PE-484/3 Improved hybrid version with valves and transistors PE-484/4 ? PE-484/5 Fully transistorised version
PE-484/9 Modern version with different layout
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In the table below, all avilable plug-in coils are listed.
In practice, only a selection of these coils would be ordered
with the receiver. Especially the lower four ranges I to IV (0.057 to 1.08 MHz)
were rearely used and were often omitted.
They may therefore be missing from a surviving unit.
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Coil
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From
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To
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From
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To
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I
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0.057 MHz
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0.114 MHz
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2630 m
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5250 m
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II
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0.112 MHz
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0.224 MHz
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1338 m
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2680 m
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III
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0.220 MHz
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0.443 MHz
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676 m
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1363 m
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-
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0.443 MHz
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0.498 MHz
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602 m
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676 m
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IV
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0.498 MHz
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1.08 MHz
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278 m
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602 m
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V
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1.06 MHz
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2.225 MHz
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135 m
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283 m
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VI
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2.18 MHz
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4.51 MHz
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66.5 m
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137.5 m
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VII
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4.45 MHz
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8.8 MHz
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34.1 m
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67.3 m
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VIII
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8.6 MHz
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12.9 MHz
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23.25 m
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34.8 m
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IX
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12.7 MHz
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17.0 MHz
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17.65 m
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23.62 m
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X
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16.8 MHz
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20.6 MHz
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14.55 m
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17.85 m
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The PE-484 came in the unobtrusive leather briefcase shown in the image on
the right. It looks like a regular briefcase, but was in fact purpose-made,
and offers space for the receiver and its accessories.
After opening the case, the upper half of the front side can be folded as
shown, giving access to two leather bags and four coil pack positions.
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The frequency range of the receiver (57 kHz to 20.6 MHz, with a gap from
443 to 498 kHz) is divided over 10
bands, each of which requires a special cylindrical coil pack, that can be
inserted into the receiver and acts as a frequency scale.
One coil pack was usually installed in the PR-484 receiver.
The four most frequently used coils could be
stowed in the hinged flap
of the leather briefcase (for quick access)
whilst the remaining ones were kept in a
leather container.
➤ Overview of plug-ins
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One of the most striking features of the PE-484 — copied from the WWII
Gürtelpeiler — is the field-strength
meter that is disguised as an unobtrusive wristwatch. It allows the
user to check the field-strength of the clandestine (spy) radio signal, whilst
pretending to be checking the time.
The wristwatch meter is also a rare item, which is commonly missing from a
surviving PE-484, as it was often taken as a souvenir by former users.
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The PE-484 can use several antennas. First of all, it can use the internal
ferrite antenna. For good direction finding however, it needs a (directional)
loop antenna and a vertical (omni-directional) help-antenna.
For the latter, two variants are available: an antenna pair made of
cloth-encapsulated wires, and a set of fixed antennas.
The fixed antennas are intended for field use in combination with the
tripod and antenna head.
The image on the right shows the body-wearable loop antenna.
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A standard inconspicuous brown leather briefcase was used for storing the
receiver and the basic accessories, such as the additional tuning coils,
the user manual, the antennas and the wrist-watch field strength indicator.
In most cases, this is how the PE-484 set was delivered. In the extended
version, the briefcase was packed inside a larger leather case, together
with a tripod and some other accessories. It made the PE-484 suitable for
open field use and static measurements.
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The PE-484 receiver and all of its accessories can be stored inside a rather
large black leather suitcase.
This includes the standard brown leather briefcase that is intended for
daily use, and a tripod for the fixed directional antennas.
The images below show how the various parts are stored inside the high
quality suitcase. The rightmost image shows the antenna head that can be
mounted on the tripod for outside field use.
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The PE-484 can also be used for static field measurements when mounted on the
supplied tripod. A special antenna head with two fixed antennas is then
connected to the receiver.
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A complete PE-484 set comes with many other accessories, including a
screwdriver, rain coat, waist belt, battery charger, etc. Some of these
accessories are listed below. Others may be described elsewhere on this page.
For connectivity between the various components of the set, some thin short
cables are supplied. These cables all have a rather rare 2-pin plug at the
end. Be very careful with these cables and plugs are they are extremely
difficult to replace.
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The PE484 receiver is easily opened by loosening two screws at one end
of the back panel. The other side of the back panel has a hinge, so that you
can swing it open like a door. Opening the back door, reveals the electronics
inside the receiver. It consists of two miniature Telefunken valves and 5
first-generation transistors.
To the right of the electronic circuit are two mechanical filters.
The batteries are in the front compartment. They are mounted in three
battery holders that surround a 5-pin 270° DIN socket.
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PE-484 in block buster movie
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The PE-484 direction finder can be spotted in the 1977 Dutch
block buster movie
Soldaat van Oranje
(Soldier of Orange).
In the scene in which the German Sicherheidsdienst (SD) tries to locate
the Robbie's clandestine transmitter, an SD employee wears the
PE-484 on her body and uses the wrist-watch meter to establish
the location of the transmitter by measuring the field strength.
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The female SD employee — who is actually a Dutch collaborator — is played by
actress Bruni Heinke. In the previous scene she is helped by her male
colleague – played by actor Rijk de Gooijer – to
install the PE-484 under her clothes.
The first part of the search is carried out with a receiver that is installed
in the back of a small laundry truck. it is used to roughly establish the
area in which the transmitter is located.
Once the region is narrowed down to
just a few houses or blocks, the PE-484 is used for the final part,
by finding the position with the highest signal level.
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It should be noted that the PE-484 is strickly speaking out of place here.
It was used to replace the original wartime Gürtelpeiler
(waist belt direction finder) which the production team was unable to obtain.
Original Gürtelpeilers
are extremely rare, and the PE-484 is similar enough – both in appearance
and in functionality – to act as a convincing alternative.
It should also be noted that in the movie it is the German
Sicherheidsdienst (SD)
who locates the clandestine transmitter, whereas in most cases this was the
law enforcement work of the German Ordnungpolizei (Orpo).
The actual PE-484/2 that was used in the movie Soldier of Orange,
came from the
collection of Dutch collector Cor Moerman. It later became part of the collection
of Museum Jan Corver in Budel (Netherlands) – the Dutch Ham Radio Museum
– and is now part of the Crypto Museum collection [4].
Movie screenshots courtesy and copyright 1977, Rob Houwer Film Company
(Netherlands) [3].
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PE-484/3 289 092 Crypto Museum PE-484/3 289 078 Museum Jan Corver Crypto Museum
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- Telefunken, Kleinstpeilgerät PE-484/2 Teil 1
Vorläufige Kurzbeschreibung und Bedienungsanweisung (German).
User Manual for the portable direction finder PE-484/2.
Germany, April 1959.
- Telefunken, Kleinstpeilgerät PE-484/2 Teil 2
Vorläufige Beschreibung Wirkweise mit Schaltbildern (German).
Service Manual for the portable direction finder PE-484/2.
Germany, April 1959.
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- Kommerzielle Nachrichtengeräte und Hf-Transistoren
Funkschau 1958, Heft 23, pp. 533-534.
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© Crypto Museum. Created: Tuesday 20 April 2010. Last changed: Tuesday, 27 December 2022 - 14:49 CET.
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