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Multiplexutrustning TM-1
(Carrier telephone system for 1 + 16 channels type STR 113/22)

Tillverkare N.V. Philip´s Telecommunicatie Industrie, Hilversum Nederland

Utdrag ur originalbeskrivning fastställd 1/4 1958. Från krigsarkivet.

The STR 113/22 carrier telephone system is designed as modulation equipment for sixteen telephone channels and will be mainly used in conjunction with radiolink equipment.

In addition to the sixteen channels which are modulated a v.f. channel may be used. Speech in this channel is not modulated in the carrier. For this reason the total number of channels is given as 1 + 16.

Two 8-Channel groups are formed in the transmitting section of the system. The eight channels of a group are each modulated with a channel carrier (12, 18 …54 kc/s), after which only the lower sidebands are passed by the filters. These lower sidebands are combined, resulting in two groups in the 6 … 54 kc/s frequency band.

One of these groups is modulated with 114 kc/s resulting in the 60 … 108 kc/s group as the lower sideband. This group is combined with the other group (6 … 54 kc/s) so that the 16 h.f.channels occupy the  6 … 108 kc/s band (see frequency allocation, ND 044 68e).

Tile frequency band of a speech channel is 300 … 3400 c/s, whilst the channel carrier spacing is 6 kc/s.

The installation is suitable for the transmission of D.C. signalling impulses from an automatic exchange. A 4300 c/s signal is used for signalling within the channels; this is, of course, outside the speech band.

An additional relay set is provided for each channel by means of which it is possible to connect a number of magneto subscribers' sets or a magneto exchange direct to the carrier telephone bay. In the case of automatic exchanges these relay sets are put out of service.

The v.f. end of the system can be adapted for two-wire or four-wire operation. For this purpose each channel unit contains a hybrid transformer with line balance.

The amplifiers in the transmitting section of the system contain a circuit by means of which equalization of part of the cable can be obtained. The equalization of the remaining part is effected in the receiving amplifiers of the other terminal station.

The equipment is mainly housed in units suspended from the bay. The rack consist of a number of steel struts with cover plates and mainly contains wiring, fuses, terminal  blocks, a number of panels with equipment permanently connected to the bay wiring and a number of receiving relays for signalling.

The units are sealed by means of die-cast covers, so that the components in these units need not be canned separately. In this way the components can be mounted compactly and are easily acessible.

The use of ferroxcube as core material for coils and transformers made it possible to keep the units fairly small.

The connections between the unit wiring and the bay wiring are established via contact blocks mounted on the units and the bay.

The entire equipment is finished in light-grey lacquer.

The equipment as a whole can be divided into three parts:

  • Transmission or system equipment
    This term includes all the equipment in the transmission path.
  • Carrier supply equipment
    This equipment generates the carrier frequencies used to modulate the speech signals.
  • Power supply equipment
    This equipment supplies supply voltage for the various units.

One terminal bay (STK 533) contains equipment for one complete system, in other words 16 h.f. channels with a relay set for each channel, one v.f. channel, carrier supply equipment and power supply equipment.

Technical data

Type of system:

Single side-band with supressed carrier

Number of channels:

1 + 16

Frequency band for speech in a channel:

300 … 3400 kc/s

Frequency band for h.f. channels:

6 … 108 kc/s

Frequency band for v.f. channels:

300 … 3400 kc/s

Signalling frequency:

4300 c/s

Frequency space between the channel carriers

6 kc/s

Number of modulation stages

1 or 2

Levels and impedances


Channel units STV 1611 … 1618






Transmitting end:





   Input, two-wire 1 mW

0 db

0 db

0 db

600 ohms

   Input, four-wire

-3,5 db

-12,6 db

-3,5 db

600 ohms

Receiving end





   Output, four-wire

+3 db

+3 db

-4 db

600 ohms

(This level may be varied between -2 db and +4 db with respect to the nominal value by adjusting amplifier in the channel unit)

   Output, two-wire

0 db

0 db

-7 db

600 ohms

H.f. output, transmitting end (system)

-4 db max.

150 ohms

H.f. input, receiving end (system)

-38 db min.

150 ohms

Signalling level at a point of relative zero level

1 mW  -6 db


Intelligible crosstalk attenuation between two channels

≥65 db


Noise in a channel at a point of relative zero level

<-65 db


Power supply


   Mains voltage

220V A.C. ±5%

   Mains frequency

50 … 60 c/s

   Power consumption

about 500 VA

Dimensions of the STK 533/11 bay



520 mm (20½")


2010 mm (6' 7")

   Depth (with units)

290 mm  (11 3/8")


about 420 kg (924 lbs)


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