In ground installations and vehicles with the E52 Köln a morse key of the type "Baumuster T1", also called the Siemens key, was used. It measures
85 x 155 x 50 mm (b x d x h) and weighs around 0.5 kg. The bottom plate is metal and it is rubber clad to prevent slipping. There is a bakelite case and a
rubber covered cable with a 2-pole connector.
The key is marked "Baumuster T1 Anf. Z: Ln 26902", where Ln means Luftnachrichtentruppe.
Inside the key has a checkout stamp BAL (BauAufsichtLuft).
My key is in very good condition with the original cable and connector. I bought it at eBay in Germany for 30 euro in July 2007.
In the aircraft the smaller and lighter key T2, called the Lorenz key, was used. The names come from the industries that initially developed the keys, they
were eventually built by several factories.
Headphones
I bought a pair of headphones from the same seller. They are the same age, with leather covering and cotton spun original cord with a connector of the same
type as the key, the connector fits in the headphone outlets of the E52 Köln. The phones are marked Dfh.a and 44. The figure 32 is painted in large size with white paint
on one of the cases.
Spare valves
The receiver E52 used the valve RV12P2000 in all functions except the rectifier, a total of 10 valves. In the rectifier two 12D60 were
used. The photo shows some of my spare valves manufactured by Telefunken and TeKaDe. Valves of this type were made also by other
manufacturers, i e Valvo, Lorentz, RFT, Opta and Philips. After the war they were still made in East Germany by RFT in the company
VEB Röhrenwerk Anna Seghers even into the fifties.
RV12P2000 is a pentode of miniature glass type with a 6-pin socket and a top connection for the grid. It was pushed into the valve
holder which was surronding and thus protecting the valve. All the valves in the E52 could be quickly changed from the outside without
disassembly. The small tool shown in front of the valves was used to withdraw the valve.
The valve has 12V heater voltage and 150 to 200V anode and screen grid voltages, the amplification
factor is 1,5 mA/V. The valves were marked on the socket with the week and year of manufacture, i e week 14 in year 1943 in the
photo.
Even today there are plenty of valves around and they can for example be bought from Norsk Radiohistorisk Förening NRHF or
over eBay.
Valve tester
To be able to test the valves I have made a simple valve tester with a valve holder, 10 kohm anode resistor, 100 kohm screen grid
resistor and 1 kohm cathode resistor. These values give a good working point for the valve when fed with 200V from the power supply,
and it is easy to calculate the currents by measuring the voltages across the resistors. The amplification is calculated over the entire
frequency range by feeding the grid with 1V from a signal generator and measuring the output with an oscilloscope.
