The TI-462 was a very compact and lightweight receiver.
Despite the fact that it contains 11 valves (tubes), it measures only
19 x 10 x 5 cm and weight just 1.27 kg. Most components were
manufactured by Tesla,
but the valves came from Valvo and Raytheon 2 .
Its physical appearance is similar to the receiver of the American
When it was used as part of a spy radio set, the TI-462 was usually
powered by the transmitter. It was also supplied for stand-alone use
however, in which case it came with its own power supply unit
(PSU) or external battery.
The TI-462 A was developed in 1956 and was released the same year as part
of the three-piece PLUTO spy radio set.
It was used in international espionage, mainly in West European countries.
Although the set came with
a small morse key that was mounted inside the accessory box, the
receiver had a built-in automatic morse keyer with a removable paddle
at the front right. The keyer was connected to the transmitter via the
6-pin 270° DIN connector at the rear right.
A modified version of the TI-562 A was supplied in 1962 with the
SIRIUS I spy radio set. The differences with
its predecessor were the modified frequency range and the omission
of the automatic morse keyer,
as the SIRIUS set came with a complementary
high-speed morse burst encoder.
Apart from engraving the new frequencies, the enclosure was left unchanged,
which accounts for the three unused holes at the front right corner
of the device shown above.
Správa 6 refers to Government Department 6: Communication Technology.
Although Valvo and Raytheon were European and American manufacturers,
who would normally not supply a country behind the Iron Curtain, some
Eastern Block countries, like Hungary and Czechoslovakia, often managed
to get Western components anyway, by ordering them via a neutral country
The image below shows the PLUTO receiver as seen from the rear right corner.
A 6-pin DIN plug
is used to connect it to the transmitter from which it
gets its power. If necessarry, a simple morse key can be connected to the two
banana sockets at the right. Alternatively, on the TI-462 only, a plastic
paddle can be mounted at the front right in order to use the built-in
automatic morse keyer.
Two crystal earphones can be connected to the sockets
just above the morse key sockets.
As the receiver was commonly used for the reception of
morse signals (CW),
a Beat Frequency Oscillator (BFO) is present in order to produce an audible
tone. It can be enabled with a slide-switch at the front edge. The desired
frequency range is selected with the band swich and the frequency can be
adjusted with the large tuning ring at the side. Fine tuning is possible with
the VENIER dial. The frequency scale can be calibrated by means of the
built-in calibrator at the front.
There are at least two different versions of the TI-462 A receiver, but
it is not possible to determine the variant from the serial number. It is
likely that existing receivers were later modified for newer requirements.
The following versions are currently known:
- Mark I
The initial 1956 version of the receiver had two frequency ranges:
2-4 MHz (range 1) and 4-8 MHz (range 2).
Furthermore, this version had a built-in
automatic morse keyer
(also known as an elbug keyer) with a plastic
paddle sticking out at the front right corner.
- Mark II
In 1962, the TI-462 A was also supplied with the
SIRIUS spy radio set.
The two frequency ranges were modified: (1) 4-8 MHz and (2) 8-16 MHz,
new figures were engraved
in the enclosure aside the range switch.
Furthermore, the automatic morse keyer was omitted as the SIRIUS set
came with the
DÁVAČ high-speed morse burst encoder.
It is very likely that existing PLUTO receivers were modified
Although a morse key is normally not part of a receiver, the TI-462A
was equipped with a built-in automatic morse keyer that allowed the
operator to send dashes and dots at higher speed.
It is connected to the transmitter via the 6-pin DIN plug
at the right and was probably built into the receiver for convenience
In addition, a normal morse key can be connected as well.
The image on the right shows the interior of the earlier version
of the TI-462A which has a built-in keyer.
A transparent plastic paddle,
which is usually stored in the accessory box, can be inserted into a
hole at the front of the case and can be
fixed with a plastic screw at the centre.
By moving the paddle left and right,
a series of dots and dashes
is produced. The speed can be adjusted with the SPEED knob at the front
edge of the receiver. When the receiver is put back in storage, the plastic
paddle was usually removed first and stored in the accessory box again.
The automatic keyer, and hence the plastic paddle, were similar
to the PIVONKA keyer
that was issued separately as a universal keyer for
various spy radio sets.
It was also supplied as a backup keyer for radios that already had a
built-in one or that were supplied with a
morse burst encoder.
A small morse key was supplied with the radio set as a backup,
for example in case the auto-keyer was out of order, or when the
operator was not trained on the use of the automatic keyer.
The key was mounted inside the accessory box from within
it could be operated, and was
connected to the right side of the receiver
by means of two banana plugs. The morse key operates a relay inside
the receiver that in turn switches the HT voltage of the
The arm of the key can be collapsed sideways.
The TI-462A was initially developed in 1956 as part of the PLUTO spy radio
set, that consisted of a transmitter, a receiver and a metal box with the
accessories. The receiver was powered by the mains power supply unit of the
At present, we only have the receiver in our collection and are still
looking for the transmitter and the accessory box.
➤ More information
The TI-462A was also supplied with the SIRIUS spy radio set, that was
introduced in 1962. The SIRIUS transmitter was much more powerful
than the PLUTO transmitter (80W rather than 12W), making it easier to cover
a 2000 km range.
Furthermore, the SIRIUS set was supplied with a
high-speed morse burst transmitter,
making it less prone to
radio direction finding.
➤ More information
The TI-462 A is housed in a grey hammerite-painted metal enclosure that
consists of two case shells that are held together by a couple of screws
at the bottom. After removing the bottom shell, the interior can be taken
out of the top shell, as shown in the image of the receiver above.
Two variants of the PLUTO receiver are known to exist. They are both shown
in the image on the right. The one on the left is the
that was supplied as part of the PLUTO radio station in 1956.
It is built on a pertinax base panel and has a built-in
automatic morse keyer.
The one on the right is the later TI-462A
that was supplied in 1962 with the
SIRIUS spy radio station.
It is built on an epoxy base panel and is
missing the automatic morse keyer, which is the reason for the empty space
at the front right corner. If necessary, the keyer can still be fitted.
All controls and active components (i.e. the valves) are mounted at the upper
side of the unit, on the pertinax or epoxy panel. All passive components are
mounted at the compartmented bottom side.
The tuning elements of the HF and IF stages
are all at one side of the frame, so that they can be accessed for
alignment through a removable panel in the bottom of the metal enclosure.
Below is the simplified block diagram of the TI-462 A. It is a
superheterodyne receiver with two frequency ranges. The desired
frequency can be adjusted with a variable frequency oscillator (VFO).
A crystal filter in the IF section makes the receiver suitable for
the reception of narrowband CW signals (morse), and a beat frequency
oscillator (BFO) is used to make the CW tones audible.
At the bottom is the morse keyer, which is not actually part of the
receiver but was probably placed here for convenience. It consists of
two parts: a conventional morse keyer section at the right, suitable for
driving the HT voltage of the transmitter, and an automatic morse keyer
on the left. The latter part was omitted from the later TI-462A.
When operating the keyer, the receiver is disabled and an audio tone
is injected into the earphone circuit for monitoring (side-tone).
- KEY (-)
- 175V AC (HT)
- 0V AC
- 6.3V AC (LT)
- KEY (+)
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© Crypto Museum. Created: Friday 31 July 2015. Last changed: Friday, 22 July 2016 - 14:09 CET.