Telefunken Vintage Semiconductors

Mark's research indicates that Telefunken manufactured silicon radar diodes such as this type ED702e from 1943 to 1944. Research in Leubus, now Lubiąż in Poland, had to be abandoned as the Soviet army advanced in 1944 causing the laboratory to be evacuated.

Telefunken made other microwave diodes. I have seen examples of silicon (?) types

• OA120, OA122 in typical cartridge cases. I am seeking examples of these. (Reasonably priced ones, old microwave diodes are absurdly expensive on eBay).

According to Mark, the first post-war semiconductor products from Telefunken were germanium point-contact diodes types OA150, OA159, OA160, OA161, OA172 and OA173. Early versions of these use an axial glass form with a decal around it bearing the Telefunken logo as well as the part number.

I am looking for examples of OA159 and OA173 with such decals. If you know where I might get some, please

Later versions are painted black with white lettering and just the letters TFK rather than the logo.

Telefunken made more early diodes in the OA series. The 1959 'Ausgabe' lists:

• OA126 a silicon Zener diode with suffixes from /5 to /18 denoting the Zener voltage
• OA127 to OA132 silicon high-back-voltage diodes. These may exist in a single-ended glass outline as well as axial.
• OA150, OA159, OA160, OA161, OA172 germanium types as above
• OA154Q germanium diode quartet for ring modulators

• OA174, OA180, OA182 and OA186 germanium diodes

There is also a type OA182B, which is a quad bridge of OA182 encapsulated in a plastic block.

I have also come across a miniature glass type OA460, for which I have no data.

Telefunken experimented with germanium point-contact transistors, and may have exhibited some of them at trade shows, but these were not commercialised. The only one for which I know a part number is the GC1.

I am very interested to obtain such transistors. If you know about them, or others of Telefunken's earliest semiconductors, or have have some for sale or trade, please

Telefunken then moved on to junction transistors, starting with the types OC601 and OC602 in 1954. The first versions of these used a flat case as shown in my image, unique in bearing the full Telefunken logo.

I am very interested to buy or trade for the flat-case OC601 and OC602. If you know where I can obtain them, or have have some for sale or trade, please

By 1955 Telefunken had adopted a cylindrical glass tube similar to the VASCA SO-2 encapsulation familiar from the Mullard OC71 etc.

I am looking for OC601. If you know where I can obtain any, or have have some for sale or trade, please

Next came the AF amplifier types OC603 and OC604 in 1955 using the black glass capsule. I have some OC603 sealed inside original cartons as in the image.

An oddity in the Telefunken range is that the glass tube types OC602 and OC604 exist in physically longer versions enclosed in a small metal heatsink and distinguished by the suffix 'SPEZ' (for 'spezial' presumably). My image of the OC602SPEZ shows two forms, one just a metal tube around the glass, the other with a metal fin that can be bolted onto further heatsink material.

Again according to Mark, in late 1955 Telefunken showed their first power transistor, the OD604. This is an oddity. Like many early attempts to increase power dissipation it clamps a metal heatsink around a transistor in a smaller encapsulation. This was the first of several idiosyncratic power transistor designs from Telefunken.

Telefunken subsequently issued several power transistors in a squat cylindrical outline with three leads issuing from a hole in the baseplate. The first was the OD603, an AF output type. Oddly, this seems to have been issued in 1958, several years after OD604.

The image shows unpainted and grey-painted examples. There exist also black-painted versions, possibly the earliest, some with an evacuation port on top. Furthermore, the device may have several maximum-voltage values and this is sometimes indicated by either a suffix or a number printed on the body.

The OC series continued with the group OC612 to OC615, all RF amplifiers using the SO-2 glass capsule.

The rare type OC611 is believed to be an RF type although it does not appear in data books. It uses the SO-2 glass capsule.

I am interested to buy or trade for examples of OC611. If you know where I can obtain any, or have have some for sale or trade, please

The 1959 Ausgabe also includes a triplet OC622 to OC624 of miniature AF transistors for use in hearing aids:

• OC622 - an AF amplifier.
• OC623 - a low-noise AF amplifier.
• OC624 - a low-power AF output transistor.

I am looking for examples of OC622 and OC623. If you know where I can obtain them, or have have some for sale or trade, please

Thanks to Horst in Germany I have this unusual OC6015. Radiomuseum shows one and states that it only exists as development samples, and it is possibly a selected type of OC615 for Sennheiser.

There exists another rare type: the OC6016. The superb radiomuseum site has images of it, strangely in two different outlines: the small SO2 glass cylinder, and the bespoke metal power outline used by OD603 etc.

I am looking for examples of OC6016. If you know where I can obtain any, or have have some for sale or trade, please

Telefunken went on to manufacture many germanium devices in the standard pro-Electron series AA (diodes), AC, AD and AF. I don't have an exhaustive list, but the D.A.T.A. books 'Semiconductor Diode & Rectifier Characteristics Tabulation 1961 vol VII' and 'Transistor Characteristics Tabulation 1962 Vol XII' include early ones:

• AAZ10 a subminiature switching diode
• AC105, AC106, AC116, AC117, AC122, AC123, AC124
• ACZ10
• AF101, AF105
• AFZ10, ASZ10, ASZ30, AUZ11

I have quite a few more later AC and AF types, and there are also germanium power transistors in the AD series.

TFK made germanium diodes in the AA series:

• AA111, AA112, AA132 to AA140, AA142

as well as second-sourcing some such as AA119 and AA123.

In addition to single diodes, TFK made several quadruple diode types such as this AAY18. These are intended for use in modulators. They look like they are simply sets of normal miniature glass-bodied diodes potted in plastic.

Many of the low-power transistors with the AC or AF prefix are in the tall TO-18-long (non-standard) outline such as this AC150.

Some types are embedded in an aluminium block heatsink like this AC188K (itself rivetted to an aluminium plate). These often have a suffix K for 'Kühlkörper' but I have a number of AC117 with heatsink that do not.

The 1959 Ausgabe includes AC105 in the SO-2 glass tube with heatsink fin, like the 'SPEZ' types, although 'Telefunken Halbleiter' 1959 lists it with no fin. Both publications describe it as an IF amplifier but later documents change that to an AF output transistor. It is possible this was a confusion with AF105, an IF type that has the SO-2 glass body but without the fin.

The slightly later and higher-gain AC106 is also an AF output type in the finned outline.

So do the ACZ10, the AFZ10 and the ASZ10. The ASZ30 (shown) has the glass body but no heatsink fin. I am looking for examples of all of these types except ASZ30. If you know where I can obtain any, or have have some for sale or trade, please

Telefunken made a number of germanium power transistors in the AD series, including:

• AD138, AD139, AD149, AD150, AD152, AD155, AD159, AD160, AD161, AD162, AD164, AD165, AD169

Here is an AD138 AF power amplifier. It uses the TO-3 outline, but is painted in a rather military-looking dull green-blue, and is still supplied in a valve box, even with an image of a valve on it. (The end flaps are stamped AD138 so it's the right box).

I don't intend to show them, but of course Telefunken went on to issue many silicon transistors and diodes.