What counts as portable is somewhat a matter of opinion, especially over the years. [Helge Fykse] has a portable spy radio of Swedish origin. For its time, it was considered very portable, crammed into a good-sized suitcase.
You can see the large crystal that sets the transmit frequency and a key to send Morse code. The receiver has a VFO, so it was more agile. Based on the regenerative knob, it appears the receiver was of the regenerative type. The suitcase had its own battery, and with tubes, it could probably put out some kind of signal if connected to anything metal, like bedsprings, a clothesline, or anything. There was a lightbulb to let you see when you were transmitting maximum power.
Speaking of tubes, there were five inside, two for the transmitter and three for the receiver. The radio had storage for spare tubes, and the agent could maintain the radio in the field.
You not only get a peek inside the suitcase, but a look at the schematic. The radio is a model of simplicity, but we are certain it did its job.
We love looking at exotic spy gear, especially radios.