TeKaDe logo

The German company TeKaDe is now quite obscure. Some information can be found on the German wikipedia, but this does not mention semiconductors. The company started life in 1906 as Felten and Guilleaume but in 1912 the name was changed to TeKaDe, for Süddeutsche Telefonapparate-, Kabel- und Drahtwerke AG, which means "South German telephone equipment, cable and wire works". Somewhat counter to this name, the company specialised in wireless telephone networks. In 1981 it was taken over by Philips.

In the late 1950s and into the 1960s TeKaDe manufactured germanium transistors and diodes, some of which I show below. Information about this is scarce. Some can be found (in German) on the excellent Radiomuseum site. It states that from 1955, TeKaDe was producing high-end germanium diodes and from 1956 AF-transistors. From 1958/59 semiconductor production started at the Schwabenstrasse plant but the company ceased production in 1961/62 for economic reasons.

The company logo was usually printed on devices, but sometimes just the letters TKD were used.

I am seeking to buy or trade for germanium transistors and diodes made by TeKaDe, especaily the types GST01, GST02, GFT2006, GFT30. Details are given below. I also want to buy any original data books or sheets for any of their semiconductor devices.

If you know about them, or have have some devices for sale or trade, please

Ich suche die Germaniumtransistoren und Dioden die von TeKaDe hergestellt werden. Ich möchte auch ursprüngliche Leistungsblätter für sie kaufen. Wenn Sie in diesen Transistoren oder Dioden auskennen oder haben, einiges für Verkauf oder Handel zu haben, in Verbindung.


TeKaDe G5 diode

I guess that the first semiconductors that TeKaDe made were diodes, since most semiconductor manufacturers started that way. However I am unsure about their earliest devices. They made point-contact diodes in the K and GSD series: this stands for 'germanium spitzen diode'.

The image shows a point-contact diode, GSD5/61, although it is just marked G 5/61. This qualified part number is typical of TeKaDe, except for their earliest transistors, and probably indicates a maximum voltage parameter. Some devices also have a single-letter suffix.

I am interested in obtaining other diodes by TeKaDe, especially the K series. If you know about TeKaDe's earliest semiconductors, or have have some for sale or trade, please


TeKaDe GST wanted

TeKaDe made two point-contact transistors, types GST01 and GST02. These used the typical cartridge case originated by Western Electric.

I am very interested in obtaining these transistors by TeKaDe. If you know about TeKaDe's earliest semiconductors, or have have some for sale or trade, please


TeKaDe GFT20 transistor

TKD junction transistors were all in the GFT series, although some do not include this prefix on the can. GFT stands for Germanium Flächentransistor, that is "germanium junction transistor".

The image shows a GFT20, possibly their first transistor. It does not have any identification printed on it, just the 7001 shown. I do not think that this is a date code. The shape of this device is distinctive.

The German Radiomuseum site shows a GFT20 in a slightly different can, like my GFT21 below, but their diagram shows this 'bell' shape. They state that the device is an AF amplifier, which one would expect for a very early type. Interestingly, they list three possible qualifiers: /6, /15 and /30.


TeKaDe GFT21 transistor

Here is a GFT21 transistor. It too is painted in the characteristic red, but now has the company logo and also the part number printed on it. The packaging is less unusual than that of the GFT20. There is no qualifier to the part number.

Radiomuseum lists five possible qualifiers: /15, /15A, /15B, /30 and /30A. It also states that versions were offered for hobbyists/kits with the marking NF21, NF7 or NF8.


TeKaDe GFT2006 transistor

TeKaDe made an early power transistor, type GFT2006, in an idiosyncratic cylindrical package. My image shows examples with the suffix /30, there exist other suffixes, possibly including none.

I am interested in obtaining examples of this transistor with suffix other than /30. If you know where any are for sale or trade, please


TeKaDe OC15 transistor

I recently bought this device, marked OC15 without any manufacturer, which is clearly the same case as the GFT2006. The original OC15 was Philips/Mullard's first power transistor, from about 1954/55, in a somewhat larger cylindrical can, and is very rare. There is a Valvo equivalent type 100OC. I'm a bit sceptical that TKD were experimenting with power transistors at this early time. I'm also puzzled by the code 0948, which cannot be a date of 1948!

If you know anything about this weird OC15, please


TeKaDe 21/30 transistor

Here is a later transistor in a standard TO-9 can marked 21/30. I assume that this is also a GFT21, but an improved later version, with a suffix indicating probably a voltage rating, as listed on the Radiomuseum entry.

If you have data for TeKaDe's semiconductors, or have have some for sale or trade, please


TeKaDe GFT26/8 transistor

This is apparently a TeKaDe GFT26/8, with the prefix GFT omitted as is often the case. However there are a couple of unusual aspects: firstly the brass-coloured TO-5 can is atypical of TeKaDe, and secondly the suffix /8 seems odd because it usually indicates a maximum voltage, and 8 volts is much too low. Furthermore, a Web search for GFT26 brings up a Thomson power transistor, which is not this one. So, if you have data for this device, please


TeKaDe GFT44/15 transistor

Here is a TKD transistor with very poor printing; it is marked GFT44/15B. Radiomuseum states that it is intended as an AM broadcast mixer/oscillator.


TeKaDe GFT3708 transistor

Finally this is a power transistor marked GFT3708/60. This shows that TeKaDe became relatively advanced in transistor manufacture. According to Radiomuseum this dates from 1956 but that sounds rather early to me.


I have a few other low-power TKD transistor types. However I have no definitive data for any of them, just the Radiomuseum information plus some characteristic values in the "Discontinued Transistor Data Book". If you can provide data books or sheets for TeKaDe's semiconductors, please contact me!








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