Teardown: Siemens Hilfssender (auxiliary transmitter), microwave tube based

[wkb]

Close up of the top connector connecting to the top connection of the lighthouse valve.

2nd picture shows the valve mounted into the top connector.

[wkb]

In case someone has a use for it or just wants to own this beautiful piece of German engineering please get in touch via PM.

[T3sl4co1l]

Interesting, I wonder why it's stepped -- filtering harmonics, perhaps?

So it has two adjustable cavity lengths / loading tweaks?  Probably something like, tuned plate / tuned grid oscillator.

Tim

[Alex Eisenhut]

Here is the LO from a 1L30 spectrum analyzer. It is tuned by turning the knob on top that lowers and raises two coaxial plungers inside the cylinder. I think this tunes two cavities that act as LC circuits on the cathode and plate of the tube inside. The grid is grounded, and two wire loops that pass through the triode's grid flange couple the two sections.

http://www.r-type.org/exhib/aaa1026.htm

So on the oscillator you have two wires for the filament, one connection for the B+, two coax outputs; one goes to the input mixer, one goes to a PLL, and a connection to a varactor that's somehow stuck inside a cavity with a wire loop to fine tune the oscillator. In the analyzer it is locked against a 1MHz crystal.

It's a mess to take apart, and the tube is machined to fit in there, you need the special modified Tektronix tube, a normal one won't fit and you need the holes for the loops.

[wkb]

Interesting!  Given the ident plate on my unit I do not think it originates from a measurement instrument but the pictures look sort of similar.

[wkb]

In case someone wants it, I have put it on a Dutch classified ads list for €10.  More than happy to trade for something useful too.

[cj]

What you have here is an auxiliary radar transmitter. It uses the 2C43 tube and can generate 1us pulses at 1000 pulses per second and produce up to 1.7kW.
If you google ‘pulse communication on 2300mc’ you’ll find a pdf document describing a pulse communication system using this type of oscillator.

CJ

[wkb]

What you have here is an auxiliary radar transmitter. It uses the 2C43 tube and can generate 1us pulses at 1000 pulses per second and produce up to 1.7kW.
If you google ‘pulse communication on 2300mc’ you’ll find a pdf document describing a pulse communication system using this type of oscillator.

CJ

Fascinating, thank you for the information!