Author Topic: Teardown: Siemens Hilfssender (auxiliary transmitter), microwave tube based (Read 10346 times)

wkb · « **on:** March 20, 2016, 06:18:43 pm »

On yesterday's hamfest over in Rosmalen (NL) I obtained a rather interesting piece of kit. It calls itself Siemens Hilfssender. Or: auxiliary transmitter, built by Siemens of Germany.

It has a microwave tube, an adjustable cavity (from what I now know), it is built from silver plated brass, it weighs a ton and is testament to the proverbial Deutsche Grundlichkeit. I think it is for use around 2.4GHz (assuming I interpret the readout correctly that corresponds to the
tuning of the cavity).

I am really curious if one of the EEVbloggers has any clue what this puppy belongs to? I also wonder about it having only one RF connection? Oscillator? I cannot find a partnumber on the tube unfortunately.

wkb · « **Reply #1 on:** March 20, 2016, 06:20:42 pm »

Partnumber badge

On the bottom the adjustmet axle, with the frequency readout scale

wkb · « **Reply #2 on:** March 20, 2016, 06:23:30 pm »

on the side is a pickup for the RF sticking in the cavity (detailed picture follows)
The axle at the bottom allows adjustment of the cavity

wkb · « **Reply #3 on:** March 20, 2016, 06:28:03 pm »

Screw-on cap for access to the tube

And the cap itself, with strong spring

wkb · « **Reply #4 on:** March 20, 2016, 06:31:22 pm »

Once the cap is removed the tube socket becomes visible.

With the side cap on the cavity removed

wkb · « **Reply #5 on:** March 20, 2016, 06:36:22 pm »

The retainer ring held in place with two screws is removed, tube-socket assembly pulled from the cavity assy.

Connections between the tube and the 'outside world' are provided via silver plated slide contacts

wkb · « **Reply #6 on:** March 20, 2016, 06:37:35 pm »

Deeper inside lies a coaxial socket for the RF side of the tube.

wkb · « **Reply #7 on:** March 20, 2016, 06:39:09 pm »

Tube is fixed within its socket with yet another retainer ring.

Detail of the socket.

wkb · « **Reply #8 on:** March 20, 2016, 06:40:47 pm »

More detail on the tube socket.

Towards the other end of the cavity, the adjustment mechanics

wkb · « **Reply #9 on:** March 20, 2016, 06:45:04 pm »

Multiple gears are in place for mechanical adjustment of the cavity. The main axle adjusts 'something' in the cavity, but there is another adjustment possible using a screwdriver which controls another gear which in turn appears to move a metal tube in/out the cavity.

Other pictures will detail that.

wkb · « **Reply #10 on:** March 20, 2016, 06:47:01 pm »

Mysterious cable connection.

And more gears

wkb · « **Reply #11 on:** March 20, 2016, 06:48:42 pm »

That cable again

Note the position of the readout versus the position of the metal tube shown in the other picture

wkb · « **Reply #12 on:** March 20, 2016, 06:51:46 pm »

Note the position of the readout versus the position of the metal tube in other picture. Frequency /cavity has been adjusted

SeanB · « **Reply #13 on:** March 20, 2016, 06:53:56 pm »

That is very interesting there, a tunable oscillator in the ISM band. I would guess it was for either RF heating of small samples or ionising gas samples in a gas chromatograph.

wkb · « **Reply #14 on:** March 20, 2016, 06:56:44 pm »

RF pickup unscrewed from the cavity

wkb · « **Reply #15 on:** March 20, 2016, 06:58:58 pm »

Detail of the extended tube

wkb · « **Reply #16 on:** March 20, 2016, 07:03:00 pm »

Right.. these are all the pictures I have sofar. Wondering if I want to take the cavity assembly apart or not. Chances are I will not be able to reassemble it

TimFox · « **Reply #17 on:** March 20, 2016, 08:16:00 pm »

The actual tube (valve) in your picture is a "lighthouse" disc-seal triode. The American tubes with that construction and octal base include the 2C40. See http://www.radiomuseum.org/tubes/tube_2c40.html
To operate at high frequencies, the cathode (through a capacitor) and grid connections are concentric discs to minimize parasitic inductance. The heater connections and multiple cathode connections are to the octal base.

wkb · « **Reply #18 on:** March 20, 2016, 08:31:07 pm »

Quote from: TimFox on March 20, 2016, 08:16:00 pm

The actual tube (valve) in your picture is a "lighthouse" disc-seal triode. The American tubes with that construction and octal base include the 2C40. See http://www.radiomuseum.org/tubes/tube_2c40.html
To operate at high frequencies, the cathode (through a capacitor) and grid connections are concentric discs to minimize parasitic inductance. The heater connections and multiple cathode connections are to the octal base.

Thank you! Looks like the specs are like: https://www.sokoll-technologies.de/Museum/Auto/Dokumente/Datenblatt_2C40A_General_Electric.pdf. Telefunken, a leading German firm also produced them, so it can very well be a TFK tube in this Siemens design.

I'll pull it apart again to see if I can find a partnr hidden somewhere. Other than powering it up and creating the mother of all WiFi jammers I do not see much use for it myself.

T3sl4co1l · « **Reply #19 on:** March 21, 2016, 07:24:26 am »

Should be bias pins (heater, cathode/grid, plate) somewhere; simply apply the respective voltages and you get RF. Wouldn't think it would be enough for plasma -- just a few watts -- but might serve as any number of things: reference or VFO for a power amp (doing such things perhaps), or LO for a mixer in a radio set, or..?!

Tim

Nuno_pt · « **Reply #20 on:** March 21, 2016, 09:17:07 am »

At first glance that seems to me like one TWT amplifier for Microwave, the tube is similar of the 2C39.

wkb · « **Reply #21 on:** March 21, 2016, 09:46:09 pm »

I decided to take the cavity further apart. The tube/valve had no visible partnumber.

Split in two halves.

A look into the silvered cavity tube, down into the finger-stock connectors that connect to the triode

wkb · « **Reply #22 on:** March 21, 2016, 09:48:31 pm »

More close up look into the cavity.

The center connector that connects to the top of the light house triode valve.

All is beautifully machined silvered brass. Gorgeous..

wkb · « **Reply #23 on:** March 21, 2016, 09:52:32 pm »

The cavity adjustment 'piston' set for different frequencies.

wkb · « **Reply #24 on:** March 21, 2016, 10:05:57 pm »

The central connector to the triode can move in and out of a silvered tube. This is adjusted using the slotted screw I mentioned in one of the earliest posts. Not sure what it is used for. The main axle moves the 'piston' in/out the cavity, the slotted screw independently moves the tube in/out.

Clues as welcome


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Author Topic: Teardown: Siemens Hilfssender (auxiliary transmitter), microwave tube based (Read 10346 times)

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