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Luxman R-600
DC cables
Telefunken tube

Telefunken RL12P35 glass tube


I have had this Telefunken glass tube on display for as long as I can remember.  It was given to me when I was a young lad, taking my first steps into electronics.  I was simply fascinated by the tube design and had it on display.  There was an old style electronics shop in the next town, they had a display cabinet full of odd glass tubes (some 50cm high) and I was fascinated everytime I walked by.


This particular tube seems to date from the WW II era:  it is a German Wehrmacht tube, a pentode type used as amplifier.  It was specified by Telefunken as a 35W transmit pentode (Sendepentode).  At the time the technical specifications were published for "wavelenghts" rather than frequency, for this tube info was given for wavelenghts from 50m (6Mhz) to 4.5m (66Mhz).  I have also come across a schematic where the tube is being used as a 15W audio amplifier.


The breakdown of the numbering is logical:


R = Army (Wehrmacht)

L = amplifier [PA] tube

12 = voltage (12.6V)

P = pentode

35 = power (dissipation) in Watt


The tube has numbering "Nr. 156725/3942/V" at the front, possibly a production series, and at the back an octagonal stamp with lettering "8AL Z16" in it as well as a marking "R.L.M.".


Here are some shots of the glass tube Telefunken RL 12 P 35.



Front of tube.

Back of tube.

Lettering at front.

Top with A and B screw terminals.  Believed to be for Anode and Grid (Bremsgitter) connections.

Bajonet locking type 5-pin socket.



I have seen this tube advertised as N.O.S. on Internet sites, quite unbelievably it is still available!




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