====== Multi-channel adaptor MK-1 ======
**Multi-channel adaptor MK-1**, company designation **ZT 11c**; manufactured by [[Brown Boveri]].

Around 1946/49, [[Brown Boveri]] developed the **MK-1** multi-channel adaptor, which could simultaneously operate two wideband (voice) and two narrowband (morse code, teletype) channels, to use a single microwave connection for the simultaneous transmission of several calls or teletype signals.

The **MK-1** was used with the [[SE-213|TLD (SE-213)]] decimeter wave station.

{{:images:zubehoer-richtstrahl-mk1-bw.jpg?direct&400|Mehrkanalgerät MK-1}}
===== Technical data =====
  * [[Principle]]: [[multi-channel adaptor]], frequency multiplex
  * [[Operation modes]]: two wideband channels (telephony), two narrowband channels (telegraphy / telex)
  * [[Frequency range]]: transmission of telephony channels 0.3 - 3 kHz and telex channels 1.4 - 1.6 kHz

==== Power supply ====
  * From the [[TLD]] mains power supply: Anode voltage 320 Volt and heaters voltage 12.7 Volt.

==== Dimensions ====
  * Multi-channel unit MK-1/A: 364 x 439 x 256 mm, 35.4 kg
  * MK-1/Z call unit: 364 x 439 x 256 mm, 23.6 kg

==== Accessories ====

{{:images:zubehoer-richtstrahl-mk1.jpg?direct&600|Multi-channel unit MK-1}}
===== Operation =====
The **MK-1** multi-channel system comes in three chests and is supplied with power from the [[TLD]] power supply.

The actual **Multichannel unit MK-1/A** (the multiplexer) contains four channel units and a measuring unit; the system has a modular structure. The set contains  from the left the two telephony units TF1 and TF2, the measuring unit to do control measurements on the modules and the telegraphy / teletype units TG3 and TG4.

The call unit **MK-1/Z** is used for call signal forwarding on the two telephony channels TF1 and TF2; no call forwarding is provided or possible for the narrowband telegraphy channels. The call forwarding unit MK-1/Z contains the two call units RF1 and RF2 and the call generator RG.

The box contains two canvas bags, each with a **keying unit**, a **morse key** and a pair of **headphones**; each keying unit is powered by two 4 V batteries in a compartment on the bottom of the set, one of which actually powers the keying unit and the second is a reserve battery.

The speech channels are transmitted above and below the two carrier frequencies 12 and 18 kHz:
| Channel 1|Channel 2|Channel 3|Channel 4|
|Carrier frequency|12 kHz|18 kHz|12 kHz|18 kHz|
|Modulation frequency|300 - 3000 Hz|300 - 3000 Hz|1.4 - 1.6 kHz|1.4 - 1.6 kHz|
|Transmitted sideband|9 - 11.7 kHz|15 - 17 kHz|13.4 - 13.6 kHz|19.4 - 19.6 kHz|

===== Technical principle =====
Multi-channel adaptor using frequency-division multiplex technology for the transmission of two speech and two telegraphy or teletype channels.

==== Tube configuration ==== 
  * seven [[ECH21]] tubes in the Mk-1/A multi-channel adaptor, three [[ECH21]] tubes in the call forward unit

==== Development ====
{{ :images:zubehoer-richtstrahl-mk1-kiste.jpg?direct&200|Mehrkanalgerät MK-1, Kiste}}The system was developed together with the [[SE-213|SE-213 (TLD)]] from Brown Boveri in 1942/45 and ordered in 1946 only in the quite small number of 26 (or 22 according to the "Dokumentation Funkstationen") sets at CHF 14'250 each. Because of the lack of multi-channel adaptors, the [[TLD]] as not beeing considered as useful in many situations and by many tactical commanders.

Delivery of the sets was delayed until 1950 and they were liquidated around 1961.

==== Deployment ====
The sets were used in the Fk Kp and Fl Uem Kp for radio relay connections together with the [[TLD]]. As the sets were ordered in insufficiently small quantities, the TLD connections could not play its advantages and the system was only used for point-to-point connections in rare occasions.

{{gallery>:images?zubehoer-richtstrahl-mk1*.jpg&0&80x80&lightbox&showtitle&titlesort}}

===== Technical documentation =====

==== Further information ====
  * [[https://www.hamfu.ch/de/geraete/geraet.php?id=126|MK-1 on the Hamfu website]]