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BND AM broadcast receiver
- wanted item
The UHU was a small fully-transistorized receiver that was developed
in the mid-1950s by Wandel & Goldermann in Reutlingen (Germany).
It was introduced in 1958 and was commonly supplied as an additional
receiver for the SP-15 spy radio set.
The official designator is BN-48.
Many thanks to Jim Meyer [1] for supplying images and further
information about this receiver.
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The unit measures approx. 145 x 95 x 40 mm and is housed in a metal
hammerite-painted enclosure. The case is water resistant and rubber
gaskets are used to protect the circuitry from moisture.
The receiver is completely built around the
AF-125; one of the earliest Germanium HF transtors that were
also used in its 'big brother' the FE-8 receiver (BN-58).
Circuit diagram here.
The image on the right show a typical UHU receiver [1].
The top surface hold the frequency scales. All connections are
at the rear,
whilst the controls are on the side panel
at the right.
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The receiver covers a frequency range from 2 to 9 MHz, divided over
two frequency bands (2 - 5.1 MHz and 5.1 - 9 MHz). The band selector
is a three-position switch which also acts as the power switch.
In the center position, the receiver is switched OFF.
The unit is powered by a single 9V battery (at the back)
and has no external power
connection. To save power, the dial light is operated by a momentary
push-button. A pair of headphones are connected to the rear panel.
Antenna and ground wires are connected to the 2.5 mm banana-type sockets
at the side panel. A couple of meters each will be sufficient for good
reception. The free running Variable Frequency Oscillator (VFO) is not
as stable as the later synthesizer-based alternatives, but it is good
enough for the reception of the AM broadcast stations (i.e. the famous
number stations) that were operated
by the German intelligence service, the Bundesnachrichtendienst (BND).
For the 2nd IF stage, a 455 kHz ceramic filter is used.
For the reception of CW signals (morse), the built-in Beat Frequency
Oscillator (BFO) can be switched ON by pulling the large BFO disc.
The receiver would still be useful today, for example as part of
an amateur QRP station!
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The UHU receiver was sometimes supplied as an extra receiver
with the SP-15 spy radio set.
The image below shows the suitcase version of the SP-15 in which
the UHU is strapped-in in the right half of the case (at the front left),
next to its 'big brother' the FE-8 (BN-58).
Also in the right half is a power supply unit (PSU)
and an RT-3 burst encoder.
The latter was used to send messages
in morse code at very high speed in order to minimize the risk
of interception and detection. The left half of the case contains
the usual components of the SP-15 set: the mains transformer,
a battery adapter, the transmitter and the headphones and cables.
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The UHU is housed in a die-cast aluminium enclosure. The internal
circuits can be accessed from the top as well as from the bottom
by removing the cover panels. When
accessing it from the top,
most of the space is taken up by the two frequency scales
with a small light bulb in the middle.
Accessing the interior from the bottom,
gives access to the
electronic circuits. At the center, the rear of the adjustable
capacitor is visible. At the bottom (the shiny metal panel) are
is fine tuning for each of the frequency ranges.
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This receiver is not (yet) part of our collection.
The images, the circuit diagram
and the description of this receiver
were kindly supplied by Jim Meyer [1].
Crypto Museum is currently looking for an UHU receiver.
If you are able to offer one, or if you are able to supply
additional information please contact us.
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- 2 - 5.1 MHz (yellow)
- 5.1 - 9 MHz (green)
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© Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Wednesday, 01 January 2014 - 09:03 CET
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