The all-round sound combination , RTK for short , is a brand of the Lippstadt-based company Hella for a structural unit made up of one or more (usually blue) rotating beacons and a special acoustic signal system for the use of access and special rights . They are also available without a secondary horn and with beacons of different colors. The name "Rundumtonkombination" and the abbreviation "RTK" are also used colloquially for similar devices from other manufacturers.
This combination is available in a wide variety of designs. The most common is the built-in roof structure perpendicular to the direction of travel.
The Hella company launched the first version in 1973 with the Hella RTK 1. Hella produced or produces the RTK series with the types RTK 1, RTK 2 (prototype only), RTK 3 (SL) , RTK 4 – SL, RTK 5, RTK 6 – SL, RTK 6 – SL LED, RTK 7, RTK – VE and RTK – QS.
Various modules were / will be installed as light sources:
- KL-ER: Rotating mirror made of incandescent lamp with reflector
- KL-MR: two rotating mirrors per dome
- KL-XR: Xenon flash module with trough parabolic reflector (single flash)
- KL-LR2: LED beacon, built into RTK 6 – SL LED, RTK – QS and RTK 7
- KL-XL2: double flash module in which RTK 5, RTK – QS and OWS-X are installed
- KL-XR2: Flash module from the RTK-QS (various flash patterns and radiation directions switchable)
There are various manufacturers of all-round sound combinations, but they have to be named differently because of trademark protection: Hänsch warning systems (DBS 2000/3000 or DBS 2000/3000 LED and DBS 975 or DBS 975 LED, DBS 4000, DBS 5000), Pintsch warning systems Bamag (TOPas, Opal, Zirkon) or Federal Signal .
Pictures of special signal systems can be seen on some private pages of collectors: