Five pre-60's early transistor portables

Tesla T2800 portable

Brands and types: From left to right: A Novak, of Belgian origin, no type number, from estimated 1960. The Dutch Erres RA601P from 1960. The 2 smaller radios are German: the Grundig Boy 59E from 1959, and the Nordmende Mambo from 1959. The last one is the Tesla T2800B "Mir" (means "peace") from the former Tsjechoslowakia. It was produced from 1960 up to 1963, according to Martin Hájek. Before WWII the factory was called Telefunken-Radiotechna.

Cabinet: The Novak is all plastic built, the rest has wooden cases. All are covered with some kind of leatherette.

Semiconductors: Of course the first commercial generation of transistors has been used: those black painted tiny glass tubes, a few mm's in diameter and looking fragile. Sometimes one finds a design originally intended for the real tubes, where the transistors are soldered to the original tube bases. The three wires were lead through the hole in the middle of the base, the transistor itself peeping out that hole like a tiny fungus, like an alien and hostile device...
Probably the manufacturers were a bit confused about how to handle these new "tubes without a filament" substitutes. Printed circuit boards were not very common at the time.

Power: 6 or 9V, supplied by fat D-cells. The Tesla takes 4 C-cells.

Bands: The Novak has 4 AM bands, the others have 2. The Tsjech Tesla only receives MW. Besides, the Novak has a dial light and is considered to be a more luxury radio. But the Erres can be used with the car antenna.

Obtained: I found the Novak in a 2nd hand shop for a few guilders, it didn't play that time. The Erres I got from my brother. The Mambo was one of 11 I bought at one time from a guy with a financial problem: his oldtimer car..... The Grundig Boy came from a flea market. Of course all radios came with worn out batteries, leaking acid around but with little harm done luckily. Finally, the Tesla was a gift from fellow collector Gerard Tel, who found this nice radio on one of his trips to Prague.

Condition: The Grundig needs a lot of work to get it proper again. The rest are quite OK. The Erres has a small crack in its plastic dial. The antenna of the Novak, broken at the picture, has now been repaired. I am not sure about the antenna of the Grundig. The top is simply bended, probably the original tip is missing.
After removing the paint stains (which I found out, many radios have!) the Tesla looks handsome now.

Working: I had to repair the Novak and the Nordmende Mambo. Who said transistors were invented to have eternal life? As I often found, the early transistors are unreliable and can die without a warning. Also in the Mambo: it stopped playing suddenly. A check told me that the output stage had blown out. I replaced them with 2 more recent germanium transistors and after that it played well again. Of course I left the originals with the radio.

The Tesla has a sticker in the back, saying: Don't use worn out batteries, replace those by new ones. If not in use for a longer period, remove the batteries. Nowadays we are adviced to replace all batteries at once, not only the bad ones! Therefore the radio should be equiped with a testing lamp (my radio hasn't), to check each individual battery. All batteries were stacked in a paper tube, to keep them in a row (my radio had no tube, I made one myself). As some people wrote me: it is not wise to combine batteries of several levels of load, as this can result in every battery to leak! Maybe not the modern ones, but surely the older types. As Martin wrote: he has 10 of these radios, only 2 having the test bulb in the back.

Here you find the text on the sticker in the back (200 Kb). Martin explained that the logo in the right corner below means: ESC. This is an electrotechnical institute giving hallmarks for electrical products. So comparable to the German TÜV, the Dutch KEMA institute or the US FCC. I found out that the "n.p." in the companies name on the left, means "narodni podnik", which is a "company owned by the people", and Prelouc is the city where it was produced. (translation thanks to Gerard Tel and Martin Hájek).