Unidentified spy radio set
Minature valve-based spy radio set
It doesn't happen very often, but here we have a Cold War
spy radio set
of which the origin is a mystery to us. For this reason we
are asking your help in identifying it.
The set is described
in Louis Meulstee's book Wireless for the Warrier, Volume 4 
as the 'French 1950s Miniature', but recent research has revealed that
it most likely is not French but probably East-European.
The modular spy radio set consists of three small identically sized
metal boxes, each of which has a top lid and measures
approx. 16.5 x 8.5 x 6 cm. A complete set consists of a
mains power supply unit (PSU),
a transmitter (TX)
and a receiver (RX). At least two different versions
of the set have so far been identified.
The image on the right shows two different versions of the transmitter
and a (modified) receiver, as they were found by Crypto Museum in Austria
in 2013. They are described in more detail below, along with a complete set.
As you can see in the image above, the set came in two colours: black
wrinkle paint and green wrinkle paint.
The receiver covers a contiguous frequency range of 3.5 to 8 MHz.
On the crystal-operated transmitter, this is divided over two ranges,
marked I and II (or 3 and 6 on the later version). The only known photograph
of a complete set is this one, made by Rudolf Staritz :
The same photograph is also shown in the book
Wireless for the Warrier, Volume 4 of 2004 .
From top to bottom it shows the PSU, the transmitter and the receiver.
The transmitter is connected to the PSU by means of 5 wires.
The receiver gets its power from the transmitter via a 3-wire cable.
Looking closely at the above photograph, it appears that the lower two
units have a black case, whils the case of the PSU is green.
Also note the two hearing aid connectors (a black and a white one)
on the front panel of the PSU. They were probably for the
Type 2 transmitter.
Unfortunately, the origin and the current whereabouts of the above
set is unknown. For several reasons it was thought at the time that it
was made by (or for) the French intelligence agency, mainly because of
certain acccessories that were found with it.
As we have identified two different types of transmitter, we will call the
one that we think is the oldest one: Type 1. It has banana-type connectors
for the PSU, the morse key and the receiver, and is built around a single
DLL101 valve (tube) made by Tungsram. It is housed in a black wrinkle paint
case. Detailed photographs of this version
of the transmitter and its interior below.
This transmitter has two frequency ranges, marked I and II, that are selectable
with a slide switch at the bottom right. At the bottom left is a 5-wire cable
with banana-type plugs at the end, for connection to the PSU. The
wires are labelled with the voltages:
The other type of transmitter was probably made at a later date, as it is
built around two DLL101 valves. For this reason we have dubbed it Type 2.
It is housed in a green wrinkle paint case
and uses old 3-pin
hearing aid-type sockets for connection to PSU, morse key
and receiver. This type of connectors is very uncommon for spy radio sets,
but allow quick and faultless connection.
Note that the two sockets at the top left have different colours, This
was probably done to avoid mistakes when connecting the PSU, which has
two identically coloured plugs (see below). Like with the Type 1 transmitter,
the serial number is written on the scale of the meter, but note that the
meter is made by
an East-German manufacturer. Also note that the tuning
is made by RFT and that some resistors
are made by Czechoslovakian manufacturer Tesla.
The receiver in our collection is housed in a black enclosure and has a
starting with '30', which is why we think it is the earlier
model (which we have called Type 1). It gets its power from the transmitter
and although the receiver shown here has a 3-pin hearing aid-type plug,
the bakelite casting of the old 3-pin plug is still present. It was
modified for the Type 2 transmitter.
The receiver is built around three miniature battery valves:
2 x 1T4T and 1 x 3S4T. It consists of an RF stage, a regenerative detector
and an AF output stage. For CW reception, the detector can be brought into
oscillation . Check out the images below for further details.
Unfortunately, we do not have an original PSU in our collection, so the
only image of it that we can show is the one from the complete set shown
at the top of this page. We assume that this is the later version (type 2)
as it appears to be housed in a green enclosure. Furthermore it has
connections for the older transmitter (type 1) as well as two 3-pin
hearing aid plugs
(a white one and a black one) that are probably intended for connection of
the newer transmitter (type 2).
The PSU is suitable for virtually any AC mains voltage in the world,
selectable between 100 and 230V in 10V steps, by means of the
rotary selector at the centre.
Each of the units has a serial number that is impressed on the inside of
the front panel. On the transmitter, it is also written at the center of
the white scale of the meter.
On the receiver it is written at the low end
of the frequency scale. The following serial numbers are currently known:
TX type 1
BlackPhotographed by Staritz  (complete set)
TX type 1
BlackPhotographed by Staritz 
PSU type 2
GreenPhotographed by Staritz 
RX type 1
BlackCrypto Museum collection
TX type 1
BlackCrypto Museum collection
TX type 2
GreenCrypto Museum collection
It is possible that the serial numbers of the type 1 sets all start with '30'
and that '40' was used to identify type 2 sets. It is also possible that the
type 1 sets were all black and that the type 2 sets were all green, although
this is uncertain due to the limited number of units that have survived.
Please help us identifying this clandestine radio set, by providing as much
information as possible. If you know in which country the set was built,
by who it was used, if you have any documentation or if you know a collector
who has a similar set, please contact us.
So far we have identified components from the following countries:
- DDR (East-Germany)
- Louis Meulstee, Wireless for the Warrior, volume 4
ISBN 0952063-36-0, September 2004
- Rudolf Staritz, Photograph of complete French 1950s Miniature set
Obtained via , September 2015.
Any links shown in red are currently unavailable.
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