Part 3 (late 1950s to 1965)…
Here’s the next epic slice of Blaupunkt/Porsche 356 history….
Blaupunkt seemed to be one of those innovative companies that changed things for the better from year to year (rather like VW and Porsche I tend to find). In late 1958, Blaupunkt embraced Transistor technology into their car radio sets. Germanium transistors had been commercially available for a decade, but the price point was now low enough to enable car radio manufacturers to incorporate these components into their designs. The Bremen and Stuttgart models were first to receive this transistoristaion (is that a real word?!) and looked like James’s radio above. One box, slightly chunkier than usual, with no external powerpack. These new Bremen and Stuttgart models received the suffix ‘TR’ to their model names (eg: Bremen TR). These radios however, still relied heavily on valves and these would not be eliminated totally for a while.
Late 1959 saw the final two Blaupunkt models in Porsche’s list receive the transistor treatment. The Köln and Frankfurt in their new ‘TR’ guise still had a separate external powerpack, but this time it was a lot smaller and lighter with three germanium transistors on display on the outside of the casing.

Old vs. New!
There was no need to swap vibrator units around if you needed to change between 6v and 12v. The new powerpacks had internal jumper switches for changing between 6v and 12v and also (on some models), between negative and positive earth. The new powerpack could also be attached to the radio by means of a small bracket at either side. In a 356, it would sit below and to the rear of the radio when mounted in the dashboard.
In late 1961, a re-vamp was on the cards. All of Blaupunkt’s offerings were now ‘TR’ models relying on part-transisitor, part-valve technology. The face of the radio was redesigned with a new faceplate, frequency dial and pushbuttons.
Here’s a 1956-61 Frankfurt….
Here’s a August 1961 and later Frankfurt…
The early pushbuttons are much chunkier and squarer thank the later pushbuttons.
The early faceplate has a 15mm window for the frequency dial, incorporating the plastic screen. The later faceplate has a 20mm window for the dial without the plastic screen (the plastic screen is part of the radio on these later models).
The next big leap came one year later in August 1962- the release of the full transistor radio (no valves). These radios were a lot quieter and didn’t take thirty seconds to warm up when you turned them on! Again, it was the two basic AM models, the Bremen and the Stuttgart that received the ‘ATR’ (ALL transistor) suffix first, followed by the Köln and Frankfurt in August 1963. The appearance of these ATR radios didn’t alter dramatically.
In August 1964, Blaupunkt re-designed their radios and a more slim-line version of the range emerged with a much sleeker chassis and smaller, squarer powerpack with no external components…

It is interesting to note that Porsche had always demanded the ‘Green dial’ screen to match the dashboard clocks in the 356. However, from late 1963, Blaupunkt only produced dial screens with white lettering. The 356 owners would just have to live with white lettering on their radios! Another point is that if your 356 has black dashboard knobs, the Blaupunkt radios would have been fitted to match with black pushbuttons and knobs.
That takes us up to the end of 356 production!
I have some information to follow that will help you identify which Blaupunkt is correct for your 356. Very few Porsche owners opted for the AM radios (Bremen and Stuttgart) especially in later years, so to start with, I’ll give you a quick overview to help identify the era of your radio…
1956- July 1959 Frankfurt

Chunky buttons, Huge external powerpack.
August 1959- July 1961 Frankfurt TR

It’s still got the chunky pushbuttons, but now has the smaller, detachable powerpack.
August 1961- July 1964 Frankfurt TR and ATR

Slimmer pushbuttons, newly proportioned faceplate with larger dial aperture.
August 1964- July 1965 Frankfurt ATR

Same in appearance to 61-64 Frankfurt, but with slimline chassis and powerpack. White lettering only.
Part 4 will cover year codes so you can identify your Blaupunkt’s age more accurately.