German Valves from WWI

The electrode structure typical
of most German WWI valves

German valves for most of the first World War were of a very inferior electrode design, as shown at left. They had very low voltage gain and could only be used as low frequency transformer-coupled amplifiers where their current gain was useful. The transformer coupling provided all the voltage gain.

The quality of workmanship was very high, however, and the valves were usually very quiet and robust. They had very low HT consumption which was a very important factor for front-line work, where battery supply was often unreliable.

Towards the end of 1917 the Germans started producing copies of the French valve. Below are examples of both types from three manufacturers.

AEG

These are two AEG made valves captured from German positions during WW1. The first is possibly a K1 ( see these pictures). The second has an unusual electrode structure, reminiscent of the Mullard LF Green Ring. It is probably a K3, [ might be pictured somewhere on Udo Radtke's site - original link given by Andy is now a 404 - DWK ].

Siemens and Halske

This is a Type "A" low frequency amplifier valve made by Siemens and Halske. This valve is of very rigid construction and therefore very low in microphonics. The gain was insufficient for oscillation and it made a very poor detector.An example is pictured here.

Telefunken

These are two Telefunken made valves captured from German positions during WW1. The first, probably an EVN171 shows the typical German construction, the second, type EVE173 and made in late September 1917, is a copy of a French or 'R' valve, samples of which had by then been captured by the Germans. Both of these are pictured down the page on Udo Radtke's excellent site.