"Petrol aggregate"?

Can anybody help me with the following passage?

Eigner and his deputy, Mustafa Riza Tadjadod, were to come down out of the hills to the railway and plant time fuses at irregular intervals along the line, thus wrecking it in several different places. Results were to be reported to Abwehr II by means of a tiny, briefcase-sized W/T set with petrol aggregate (Model SE 100/5).

The text is about sabotage operation of the Nazi Regime in Persia during World War II. The meaning of "petrol aggregate" in this context is ambiguous for me. Does it refer to the fuel used for this W/t set (wireless transmitter)?

Most probably it refers to a portable power station (petrol-powered electricity generator) to power the radio. Check and compare the links below:

petrol aggregate

W/T set

contemporary petrol-powered electricity generators

"Petrol-aggregat" is in a number of Nordic languages and "petrol aggregate" in German, meaning "petrol (or gasoline) generating set". The set is an engine and electric generator combined ("aggregated") together. The use of "aggregate" in the English translation is an error.