Relais-Wettersonde type WSE 2, code-name Mücke

Meteorological data transponder

System called: Fledermaus


The box flaps have been pushed away of the transport box


The transponder WSE 2

Wetter-Sende-Empfänger, whether 2 stands for 2 watt transmitting power or that it is the second type of a series, I cannot judge


WSE 2; Gerät-Nr. 124-75 A; Anf.Zeichen Ln 28790 (Ln = GAF stock-number). In contrast to what you might think, Gerät-Nr. is not a serial number but a: construction drawing number. In this respect means series: 124- electrical equipment. The number 7 might stand for a packing or batch number


Inside view of the transponder WSE2

The Al screening sheet is covering the 300 MHz receiver input. Quite curious is, that they used a small transmitting valve LS3 in the receiver front-end. Its principle is a reflex-circuit, which necessitate a quenching oscillator signal. The purpose of such a circuit is, that it constitutes a negative impedance parallel onto the UHF input circuit. Please notice also the very thin white plastic housing (cover).


Viewing the previous situation from a different perspective

The switch on the top side of the set is the main on-off selector. Please notice also the line drawings lower this page. The antenna wire on the right hand-side is meant for the transponder signal at about 27 MHz. On the left hand-side is the 300 MHz signal input. Please see also the previous photo at the far end of the module, where the 300 MHz antenna is to be connected onto.


Viewing now towards the battery compartment

The 300 MHz antenna feeding point is just visible at the far right hand-side.


Maybe not clear visible is the fact that they used sometimes very thin brightly coloured PVC insulated wirings

There exist on the right hand-side of the Al frame a connector (not directly visible). Please notice the wiring diagram down this page.


The black cylindrical device carrying number 7 is the quartz crystal for 26.6347 kHz. A typical Carl Zeiss product, being one of the exceptional firms capable of producing fundamental quartz in those days


The principle of the so-called Fledermaus-Verfahren

The transponder Mücke type WSE 2 is hanging on the balloon . The ground station was pointing a narrow beam signal towards the transponder at 300 MHz. The signal was now passing through the transponder WSE 2 and was retransmitting at 27 MHz.

The purpose of this system was manifold. The 300 MHz transmitter operator did only know that he was correctly pointing at the transponder when he watched the returning signal at 27 MHz. The way the bearing in respect to time responded was an indication of wind-speed as well as its direction and distance versus the controlling 'Maus' station. Please go virtually back to the second photo of this page and notice the transparent compartment on the right hand-side of the white cylindrical container. This was carrying a so-called 'Lang-Sonde'.


The Lang-Sonde is mounted in the thin Perspex (Plexiglas) compartment visible in photo two of this series. The actual metrological sensors (for temperature and air pressure) where inside the Al cylinder in front. The 300 MHz antenna connection is partly covered on the left hand-side

The Lang-Sonde consisted also of a time-switch by which means data intervals were provided data. An example of data recorded in the 'Maus' vehicle station (refer to the next photo)


The Maus (Mouse) controlling ground station.

The 300 MHz antenna array was constituted by the two rectangular planes. The 27 MHz receiver antenna system was constituted by means of the central antenna rod. The two 300 MHz arrays were interconnected in 'counter phase' (anti-phase). Creating a 'null' at its boresight. This is providing a very sharp ' interception null' so that pointing at the moving transponder was accurately possible.


Wetter-Sender-Empfänger WSE 2 schematic diagram

It actually used only three different valve types LS 3 - RL2P 3 (without its regular Al screening/housing) and 2 x DDD 11. The DDD 11 is a typical Dutch Philips type. They were the only one making them. They must have been produced in rather big quantities, as the Germans employed them widely. Down on the right hand-side (just not visible on the last colour photo) is the power connector (typical German steel valve socket of the '11' valve series) The 300 MHz receiver is a reflex type receiver principle (considering its simplicity having a rather good sensitivity). The quenching oscillator is constituted by the left section of Rö 2 (DDD 11) down on the left hand-side. The transmitter valve is a RL2P3 (only the glass version without base, as the wires are directly soldered upon).

According Fritz Trenkle, about 1000 'Sondes' had been started. I doubt this figure, as this might have been a too low estimation. I guess, that at least some of the 'Sondes' might have been recovered.  However, the operational range was up to 180 km. According Trenkle, 6 Fledermaus-Zügen (Parties or Groups) existed in the West. These became rather relevant as, after V2 were becoming operationally, their meteorological data was a significant parameter - concerning direction (pointing at a target), but also the moment of switching off the V2 power system (Brennschluß).



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