Remote Control Set for SPIDER
KL/GRA-3686(S) 1 is a remote control set for the
SPIDER VHF military radio,
developed around 1987 by
Hollandse Signaalapparaten (HSA) 2 in Huizen (Netherlands). The set consists of two units – a local and a remote device –
and is in fact a modified version of the KL/GRA-3686 that was used with
the RT-4600 and, to a lesser extent, with
the earlier RT-3600 military radio sets.
The set consists of two similar boxes that allow the
SPIDER to be controlled
via a regular 2-wire line (WD-1/TT) that can be extended up to 3 km.
One box – the Local Control Box (LCB) –
is fitted close to the radio, whilst the Remote Control Box (RCB)
is placed at the other end of the field line.
The image on the right shows the Local Control Box C-3686A, which can
be connected to one or two SPIDER radios
via the 10-pin sockets at the left.
A standard handset can be connected to the 10-pin socket at the right.
At the far right are the terminals for connection of the 2-wire line.
The devices are powered by three common D-size dry battery cells of 1.5V each,
that are held in a cylindrical battery compartment that can be accessed
via a large circular terminator at the left.
It is believed that, given the small number of SPIDER radios
that were manufactured, only a few KL/GRA-3686(S) sets were made for the
evaluation stage of the radio.
The device shown above carries the internal HSA designator
9556 304 05300. The same designator was used for the regular version
of the set, which suggests that it was an interim (engineering evaluation) solution.
As the official designator is currently unknown, we have added the
suffix '(S)' to identify the SPIDER-variant.
HSA Huizen – informally known as SIGNAAL or SIGNAL
– was formerly known as
Philips Telecommunicatie Industrie (PTI).
It was taken over in 1990 by Thomson,
which has since been renamed Thales.
The diagram below shows a typical setup of the KL/GRA-3686. At the left
is the C-3686A Local Control Box (LCB), which can be connected to one or two
SPIDER radio sets. In case of stand-alone use, a handset can be connected
directly to this unit. In all other cases, a standard 2-wire field telephone
line (WD-1/TT) is connected to the two terminals at the right of the
At the other end, the 2-wire line is connected to the terminals at the
left of the front panel of the C-3686 Remote Control Box (RCB). A standard
H-6060 handset 1 can be connected to either of the two control boxes, and a
MODE selector allows any combination of the two connected radios for RX and TX,
allowing single-channel (simplex) or split-frequency (half-duplex) operation
A direct call between the LCB and RCB is possible, by placing the MODE selector
in the TEL position and pressing the red CALL-button at the top right.
This will ring the buzzer at the other end.
The LCB can also be used on its own, as a local SPIDER remote control unit,
for example when used inside a vehicle. In that case, the distance between the
LCB and the SPIDER is limited by the length of the
10-way cable. In addition,
it allows half-duplex operation by adding an extra radio.
In the case of the SPIDER-variant – the KL-GRA-63686(S) – a handset with
an old-type 10-pin plug was used, as the
5-pin U-229 sockets
on the front panels were replaced by a 10-pin U-79/U sockets.
All controls and connections of the C-3686A LCB and the C-3686 RCB, are
located the front panels of the two devices. The diagram below gives an
overview of the controls and connections on the body of the local control
box. At the left are the 10-pin sockets for connection of one or two
SPIDER radio sets.
Note that this is different from the standard C-3686A,
which has a fixed cable with a
5-pin U-229 connector
at the end at these
positions. The A/B selector between the two radio sockets is not used.
On a standard C-3686A it is used to select the required radio type.
At the right are the two spring-loaded terminals for connection of the
2-wire field line, at the end of which the C-3686 Remote Control Box
(RCB) is connected. At the bottom right is the socket for a standard
handset or a speaker. At the left is the MODE selector that also acts as
At the top are the
signalling features, from right to left: a CALL button (to call the remote
end), a buzzer (when called), a knob to set the buzzer volume and an
optical indicator that is used when in SILENT mode. The indicator is
shielded by a movable lid. It is also used as BATTERY indicator.
BATTCheck battery voltage level (uses the optical indicator)
TELDirect call to the RCB (telephone)
TX1/RX1Simplex on radio 1
TX1/RX1+RX2Transmit on radio 1, receive both radios
TX2/RX1+RX2Transmit on radio 2, receive both radios
TX2/RX2Simplex on radio 2
The interior of the device(s) can be accessed by loosening the four large
bolts in the corners of the front panels, and sliding off the rear case
shells. Note that the case shell holds the battery compartment which is fitted
to the main unit by means of a fixed 2-wire (red/black) connection.
The image on the right shows the interior of the C-3686A Local Control Box
(LCB). The electronic circuits are divided over two PCBs that are both
fitted to the rear of the front panel. These PCBs hold the electronics
for the audio amplifiers and the digitally encoded signal for the 2-wire
Three small PCBs with filtering components are fitted close to each of the
sockets. Furthermore, a special filtering PCB is mounted directly to the
terminals of the 2-wire interface. It also holds a line transformer,
which is similar to the transformer of a common (analogue)
The device is powered by three D-size dry battery cells that should
be installed in the cylindrical battery holder that is mounted at
the centre of the case shell. It is clearly visible in the image above.
To save batteries, the MODE selector should be set to OFF when the
device is not used.
Compared to the regular version of the KL/GRA-3686,
the following modifications are observed:
- Fixed wiring for radio(s) replaced by 10-pin socket
- 5-pin U229 socket for H-6060 handset replaced by old 10-pin socket
- Various internal modifications
A complete (original) KL/TGA-3686 configuration, consists of the
C-3686ALocal Control Box (LCB)
C-3686Remote Control Box (RCB)
IK 11-473Instruction card
Optionally, the following can be added:
The standard version of the KL/GRA-3686
can be found here.
We are still looking for operating instructions, circuit
diagrams and/or any other documentation.
Furthermore, any additional information about the use of this unit
in combination with the SPIDER radio, would be most welcome.
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© Crypto Museum. Created: Tuesday 18 December 2018. Last changed: Sunday, 22 November 2020 - 17:00 CET.