In some old photos you can see a telegraph operator at work sitting in the cart. On his right hand side there is a visible large antenna.
In the user manual for Strv m/21-29, approved October 1, 1934, is a radio labeled “Apparat 1 W Sv”. We have not found any information about that kind of radio. On the other hand, there was an army radio station labeled “1 W Br m/28” in which Br stands for portable. In comparison the accessory lists are the same for “1 W Sv” and “1 W Br”. We assume that “1 W Br” is renamed to “1 W Sv”.
These three photos of the radio “1 W Br” are taken by Björn Hörstedt at the Army Museum in Stockholm.