Exhibit detail photographs


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State of affairs: 11 October 2022

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Please notice also our new: Exhibits details page 2


On 14 June 2011 we have introduced a special webpage dedicated especially to small components, such as capacitors in various form and other small items



As this current web page is becoming too slow due to the immense load of information (data and photographs) - I have decided on 15 March that time has now come to start up an additional new webpage extension. Please do not neglect this current webpage as its content is still very noticeable!! It proved however, that in this short time span (15 March - 14 June 2011) this second expansion is already becoming over loaded!


Please notice the Berlin contribution very down this webpage!


Hüttenpeiler II mit Goniometer (HF/DF receiver with attached DF goniometer)



UHF telephone repeater for 9 channels + one technical channel (Dienstkanal)

This system was designed to operate stand-alone. Average range 125-200 km when its was positioned at an elevated point


100 WSa with post-war power supply

This power supply was particularly made for the Norwegian civil defence organisation in the late 1940s, by a German company


Lo40K39-d extra

This set was used as a spare transmitter in many U-boats. It equals to a great extent the regular Lo40K39 xx portable transmitters. Which consists of two module. One power supply and the transmitter module, both interconnected by means of a power cable. This constellation did not use cables. The wiring is a integral part of the mounting frame


Two Valve testers


RPG1 (Röhrenprüfgerät type 1)

To view its full schematic diagram, please click on the photo. Copy this file onto the folder you want, and then open it with your photo viewer. This will provide you a full size A4 printed copy

To my knowledge, this is the only German military valve tester which provides the value of the parameter S (gm), given in mA/V, straight away. Manufacturer: Dietz und Ritter (Leipziger Funkgerätebau G.m.b.H.)(also known as: Körting). It is programmed by means of special cards, like the one shown below


Coding-card of the valve-tester type RPG1, for RV12P2000

Next to it


RPG2 special valve-tester for the transmitting valve (tube) type RL12P35


Let us follow the way of handling

The tester box is being opened and a RL12P35 is placed in its socket. When the box is then closed, and the set is connected onto the mains (outlet), the valve connections at the top of the valve connect itself automatically. The tester starts first to indicate (when the test selector is set in position 1) the appropriate 220 mains voltage

Test position 2: The white lamp on the right should indicate the, eventual, short-circuit between filament and cathode (when not lightening, all works appropriate)


Position 3 is measuring the anode current, whereas at position 4 (set for this occasion), the anode current should not increase (deviate) more than two scale divisions. Otherwise its vacuum is inappropriate (not sufficient enough)


At selector position number 5, the tester is indicating that the static amplification of the tested RL12P35 valve is correct. The pointer should therefore always indicate within the green sector. This type of measurement is indicating amplification at 50 Hz. It does not guarantee that it can oscillate appropriately at very high frequencies. But it is quite likely that it shall operate as expected


FuG 101a, Höhenmesser

Dick Zijlmans is wiring our (FM-radar system for low altitude-indication)


FuG101a in working order now, although, we might have to add at the back of the antennae a reflecting plate, as to guarantee that the full transmitted energy is radiating towards us. So that we can show motion at the (altitude) range indicator in the centre, by means of a reflecting plate, or a 1/2 λ dipole arrangement, at some distance. The latter would be most informative, as we can show then that 90 °rotation of the reflecting device can extinguish the range indication. We don't know yet whether this will work. Hampering might be the existence of the metal frames of the Würzburg units, for us, just left of it


Magnetic flux-deviation detector (discriminator) with an integrated event counter, displayed at our "Rariteitencabinet" (Curiosity display). It was meant for deployment in a German naval mine (Seemine)


The previous magnetic flux-deviation detector module, though without its covering cylinder and Bakelite upper disk, which is (still) visible in the background. The number scale is to set the event-counter, which finally sets the number of triggering before the final ignition is to take place

Please, regard for details and explanations: Archive displays - section Magnetic detector


LoG1,  and right of it Störsuchmessgerät StmG 1867 and attached Su.G.1868

On the left the 4 channels current-loop oscillograph, with attached film-cassette. This apparatus was designed to be used when several values had to be recorded. Such as, for instance, temperature versus pressure in the engine inlet in respect to take-off speed. Though, also vibration levels at various points of the fuselage

The man made noise and radio interference measuring set. This portable set, with internal batteries, was also deployed to locate noise sources, as, for instance, generated by badly working (sparking) motor-brushes, car ignition ... 


Click on this drawing or line as to open its schematic diagram

SADIR receiver type R87ES

Cover removed. The various modules are clearly visible. It had a push-pull front end with 2 x 954; followed by a push-pull mixer of 2 x 954; LO 955; 1st IF 6L7; 2nd IF 6K7; detector/AVC + first LF 6Q7; BFO 6K7 and for the S-meter a dc aplifier valve M1 = NC100; power amplifier in the audio stage EL3N. It had to use an external power supply


RF stages of SADIR R87ES receiver

On the left the front-end, the pair of 954 acorn valves are clearly visible; in the centre the push-pull mixer stage on the right the local oscillator valve type 955. Its proper construction is evident

This is how the SADIR receiver type R87ES looks like when an antenna cable is connected


On 12 June 2011 I made a photo series for Exhibits details-2

I considered that the SADIR power supply is a rare device concluding with an even more exclusive item, namely the FM adapter to the SADIR R87 receiver



SADIR power supply module


SADIR Alimentation Type R87, serial number 2262


SADIR power supply connector

This device is also missing in our collection.


SADIR R87 per supply unit opened

The rectifier type 80 is missing. French design often relied on US valve technology, although sometimes modified French types as to fit in to their radios were fitted.


SADIR power supply shown from the wiring side

The electrolytic capacitors might have been changed after the war. As soft plastic was not yet being used.


SADIR FM adapter to R87 receiver series


SADIR FM module to R87


SADIR FM adapter to R87 receiver series


SADIR FM module individual covers removed


SADIR FM adapter. Its basic concept equals that of the R87 receiver

On the left and right both French modified 6J7 valves.


SADIR FM module viewing the input and detector stages


SADIR FM adapter. Viewing the audio stage

Please notice the typical French version of a 6J7.


SADIR interconnecting wiring


Some information on the SADIR FM adapter to the R87  receiver series


Schematic of the way the SADIR FM adapter should be interconnected with the R87 receiver




The next topc was initiated by discussions on the eventual receiver type used in conjuction with the Bi-static Klein-Heidelberg system



German tank receiver. This type was developed about 1937 and was employed until the bitter end of the war. Telefunken internally called it "Bogen-Gerät". It may be regarded being a rather good receiver for the range of 27.2 - 33.3 MHz. The tuning knob is not original


UKWE e inside view

It is only since recently known, that this receiver was also adapted for use in conjunction with Klein-Heidelberg. Further information is unknown. However, what is known is, that it had an extra band-switch as to select the range for  20-30 or 30-40 MHz. Günter Hütter told me recently, that he once had seen a front panel carrying type number 'UKWE-x'

Does have someone additional information on this subject, please contact us at:

Please type-in this e-mail address



We got on long-term loan, in June 2010 the Receiver - IF module of the Freya radar (~ 125 MHz)

Later in 2015, after Jan Wolthuis' passing away - this artefact had been donated to our Foundation's collection, by late Jan Wolthuis' wife.


(12)  (11 October 2022)

Freya receiver front and viewing it from the right-hand side



The upper compartments is carrying the tuneable receiver section (~ 125 MHz). The pre-amplifier is being mounted inside the ceramic case (105). The mixer valve is inside case (106). The upper valve with its puller is type RL12T1 and represents the first local oscillator. The grey valves below the front-end compartments are type AF100. A rather high-mu broad-band valve type. For some time, even Philips have bought this valve type, until they had their own superior EF50 broad-band valves


Ceramic holder of the mixer valve, which are of the so-called 'acorn type'


Shown is the compartments of the IF amplifier


The crème circular market device (01) is the oscillator quartz of the second oscillator, which provides the second IF frequency.


The power supply with cover door opened. The lower two valves are the two half-wave rectifiers type VH3 for the HT (thus making it full-wave). Above this compartment the two mercury rectifiers. To protect the eyes of the operator, the glass window is made of dark blue glass, which is filtering the ultra violet mercury spectrum. The text to the two selector switches is in Dutch language, as it was used for some time in a Dutch university institute. The glass window allows watching the behaviour of the rectifiers. 'bya' is the production code which was given to the GEMA company in Berlin (for instance, 'bou' was designated to Telefunken and 'dmr' to C. Lorenz company)


The meter panel is showing the various voltages and currents. Special is the application of flat meter types, their pointers are moving vertically. The left control is the main on-off switch, the right one is for stepping up or down the HT of the transmitter +/- 8 kV



Batterie (Akku)-Ladegerät 0-18 V 6A (Baujahr 1944)

This is a quite compact battery charger. At choice the voltage is available via the front connections or at the rear. This apparatus is very handsome and the power cord is kept inside the case when appropriate. All front controls are mounted such that these are inside the plane of the front panel. It is remarkable, that still in 1944 so much care was taken for details



RD12Tf push-pull transmitter section

Which belongs to the Hohentwiel or FuG200 radar transmitter. It could provide 40 kW pulses (PRF 50 Hz). It is a nice example of ceramic construction, where the valve interconnections is also being part of the oscillator circuitry (its physical size and geometry is giving the operational frequency band of about 490 MHz).

By the way, Hohentwiel was a historical castle north of the Lake Konstanz (Bodensee), which played a role during the terrible "Thirty Years War" (1618 - 1648). In percentage  having a higher death- and devastation rate than during the Second World War! However, it belonged to a range of code-names, which in its series had to deal with historical war places (sites). This might be in the same series as the term "Düppel"; which is equivalent to British 'window' and US-Nato "chaff". Fritz Trenkle told me a few weeks before he sadly died in March 1996, that 'Düppel' was named after the historical "battle of Düppel" in Schleswig-Holstein, which was within the series for this kind (matter) of warfare. Some doubt this, but Düppel technology was dealt with from 1941 onwards. It is most unlikely that the Germans had a secret technology, although it was totally restricted to refer to it in any sense, that they did not gave it a code-name. Some say, that 'Düppel' was, like some other things, derived from the place where the Germans for the first time found British 'window'. But that was on 24 July 1943, and they knew (and tested its properties) already since 1941! Düppel was a site rather far from the sector where 'window' was first exploited, namely during the Gomorrah raid on Hamburg. Flak was controlled by means of the small Würzburg FuSE62 D (FuMG62D), thus not by means of Giant Würzburg, which was mainly handling (controlling) fighter aircraft (some controlled friend and others watched foe aircraft). The small Würzburg possessed from its nature a practical range of say 30 km (slant-range, thus projected on the map constituting a far shorter distance). According to the ekm Rechner manual, predicting flak range was measured (handled) between 400 m and 19.9 km. Why should so far from Hamburg window stripes been found around the Schleswig-Holstein town Düppel?  Second: when we access Google, we will find the following hyperlink:    http://www.schloss-lichtenstein.de/english/zeittafel.php     The story of the 'Lichtenstein Castle' is in successive order being listed. For 1377 - 1388 - we find 'War of the Cities' and mentioning that Lichtenstein was destroyed totally afterwards. We may assume, that fighting had taken place, whether it was a battle I don't know yet, and should be investigated deeper. Here also are good signs that the code-word of 'Lichtenstein' was linked to a historical warfare. For those not acquainted with this code-name 'Lichtenstein', it was given to several types of night fighter radar; knowingly: FuG202 xx - FuG213 - FuG214 - FuG220 (= Li-SN2). By the way, a site also not too far away from Lake Konstanz. Regard also my paper on 'German airborne radar'.

Searching on 3 December 2010 for a different file in our archives, I came across one of Trenkle's references.

As this Düppel - window (chaff) discussion is not very well in the line of this Exhibits details webpage, we have decided to transfer it to a new special Düppel discussion page



Funkhorch receiver type e

FuHE e


Front panel of Fu.H.E. e

Production code 'dmr' points towards Lorenz. This does not necessarily give the actual factory where it had been built. Which may be regarded being somewhere in what is now the Czech Republic.


An indication is, that this receiver was legally obtained from the Czech Republic in 1985, thus during the Communist era . It might give the impression that its case is not genuine, but there exist an equal apparatus having serial number 118. When we got it, all valves carried date stamps of 'March 1945'. We may guess that these receivers had eventually been accepted  in the very final months of the war. They omitted scale calibration, as this is a quite comprehensive and time consuming process. They might, nevertheless, have been given it a calibration table or chard, where the fixed 'degree' scale is being exploited.



FuHE e inner section

This is of a very compact design. The upper section which we regard being empty is in fact housing the battery compartment inside its covering case. Similarly to the FuHE f (see next subject). However, this rather crude wooden case does not have this facility (thus the space is left empty). There is, nevertheless, a provision so that the power cord can be accessed on the right hand side.




Inside view of the IF section of the FuHE e

Cover plate being removed




The rear section of the previous shown module. Its engineering is like most German communication equipment very neat.

Please notice: the flat copper strip which acts a central ground-(potential)-rail, running through several stages. A technique typically for Lorenz design.



The lower section of FuHE e

The central module is carrying the BFO / frequency calibrator




Funkhorch receiver type f

FuHEe f


FuHE f

Funkhorchempfänger type f    

Not visible, production code points at the Opta Company (Leipzig)

This exceptional receiver covers 145 - 305 MHz 'Ark' means "Arktisch" which noticed that it can be operated in 'arctic environment'

Year is given '1944'

Inside view of the right hand side of FuHE f

Serial number 9050 might indicate that the actual serial number in 1944  was '50'

Again, the rather empty space above the HF section is like in the previously shown FuHE e and meant for the battery compartment. Which is an integral part of the housing box, a lid giving access to this battery section.



FuHE f with opened HF section and with partly pulled a bit rearwards is the IF and LF module

The front-end of the receiver is having acorn valves made by Philips and applied 2 V (4 x including the local oscillator). Like most 'Funkhorch' series, it is battery powered. This obligation might originate from early 1930s military requirements. Two advantages existed, being very mobile and not dependant upon mains connections in the field. A second advantage is, that it did not suffer from any kind of 'hum'. Funkhorch type f was meant to be operated by means of a 2 V Pb battery, as well as from a 2.4 V Nc (and of course a HT battery or vibrator pack). When you look on this photo on the upper left hand side, you see the instructions what to do when one of these battery types is being employed. For 2.4 volt operations, a series resistor is used. Whereas for 2 V operation, the Pb battery is more or less straight forward connected onto the valve filaments. The brown/black valves (with blue pointers) numbered 5 - 11 are all of type MF6 = RV2P700 (one MF6 is inside the BFO / frequency calibrator, thus all together this receiver is having 8 times MF6) .



Three HF acorn valves are mounted in exchangeable frames [the LO is, nevertheless, fixt mounted (soldered)]. Its accompanied RF blocking capacitors are constituted by means of mica-sheets kept between the inner and outer conductors. A simple though effective technique, sometimes employed in 1944/45




FuHE f with pulled out BFO / frequency calibrator module

The coaxial lines and connector and the electrical interconnections are clearly visible.  The coaxial connector on the left hand side is for injecting a calibration signal towards the receiver front-end (done by means of push-button on the front panel) . The right one is meant for feeding the BFO signal onto the IF module below.



The BFO / frequency calibrator section with opened window for viewing the oscillator quartz operating on fundamental mode at 16.5 MHz. Which is equal to its IF frequency. Only Carl Zeiss Jena was able to produce fundamental-mode quartz crystals up to very high frequencies (say 50 MHz). Please notice my paper on: Some aspects of precision time measurements, controlled by means of piezo-electric-vibrators, as deployed in Germany, prior to 1950.  Techniques which nowadays seems to be simple was then hardly possible. Don't forget, that we now often use so-called 'overtone crystals'. Which are not excited at their fundamental mode but at (one of their) odd harmonics. Carl Zeiss was one of the leading optical firms in the world. It produced the highest standard of precision instruments


The housing of MZSS

(for this photo session the chassis had already been pulled out)

Please click for additional details on:

MZSS Power supply for the Schreibmax

The printer meant for use together with the German Naval 'Enigma Schlüssel M4'



S&H Wellenmesser

Type Rel mse 2032a

Please click on the hyperlink above for detail photos

Wavemeter to the Berlin radar system:

FuG224, FuG240N1a and FuMO81, maybe also to Renner (modified Coastwatcher  for the 9 cm spectrum = Seetakt)

Measuring between 3190 - 3855 MHz

λ approximately  9.4 and 7.78 cm


In the second week of October 2010 we have slidely reshuffeled some table space.


We newly got a Schwabenland receiver type Ln21021

Sadly its case (Gehäuse) is missing.


Left hand side of the Schwabenland receiver. All the valves are accessible from this side. Originally the case has three lids which give access to the valves. The only exception is the BFO valve, here covered by the circular screening disk. When this RV12P200 has to be changed the receiver had to be pulled out of its case (Gehäuse)


The AS60 driver-stage plug-in module

The two valves on the left hand side are respectively the VFO oscillator and the buffer valves (LS50).


The left hand side of the AS60 driver and controlling stage. The white ceramic circular tube inside the module on the far right hand side is mounting the oscillator coil which consist of deposited silver windings. This stage has an overall Tc of 5 ppm, rather an achievement for those days for a free running oscillator stage. (See also: The page dedicated to the complete AS60 (M1K) transmitter)



24 February 2011

The following three devices are already for decades part of our collection, but had never been photographed in detail


Mr. Opitz, who made his so-called Würzburg Function Model has sent me recently a copy of a rather unique publication on the Zeiss Jena Kommando-Geräte (Predictors) Jenaer Jahrbuch Band 11. These 'Kommando-Systems' had to calculate the actual 'Flak' parameters. Please view the Jenaer-Jahrbuch website . Like predicting where an aircraft should be - computing the parameters for the Flak as well as computing the setting of the Flak-fuse-timer.


An important aspect is the way in which mechanical movements are electrically conveyed towards another system.

An old type was UG35, where, to my knowledge, the mechanical shaft-angle is being converted into a circular-lamp-display.



Geber D z. R.R.H. ... Ug. 35

R.R.H. might mean: Ring-Richtungshörer

Meant is the: acoustical direction finder

Ug. 35 is most likely similar to the lamp-arrangement-repeater as was used for early Flak 8.8 anti-aircraft guns (GL)


The encoder sectors are visible (back-cover being removed)


The encoder system including the divided sector contacts are good visible at the perimeter of the encoder-ground-plate


Please notice on the left-hand side the system output contacts




Kennungssender KUH

(sometimes known as Q-Sender)


The KUH transmitter (Sender) was the main IFF transmitter at nearly all radar ground stations. The transponder FuG25a in an aircraft re-transmitted the KUH signal towards the ground IFF receiver system type Gemse. This is why sometimes the system is known as: KUH-Gemse.(Bladwijzer12)

Our device is not in a mint state, but good enough to notice what it is about


Front side of the KUH transmitter


Left-hand-side of the KUH transmitter module

One section of the self-oscillating push-pull transmitter valve type LS50 is clearly visible. Comparing the previous photo with the above one it is clear that the LS50, like most GAF valves, are optimally shaped for employment in modular systems.


The right-hand-side of the KUH transmitter module


Rear side of the KUH transmitter module

I guess, due to lack of information, that the two coaxial tubes are acting as a balun transformer circuit. So that the symmetrical output (2 x LS50 in push-pull) is converted into a asymmetrical one.



The last photos of the new series


HF-Rls  a  402

Sachnummer 124-5521A (this is also known as Zeichnungnummer)

Anforderungz. Ln 20552 (GAF Stock number)

Hersteller eas (valid for all Siemens & Halske branches)

What can we learn from this type-plate?

It concerns a HF-Relay most likely belonging to the Wassermann M radar type (code-name Chimney), which carried type 402 (More or less equal to Navy type FuMO331). What is known as Werk.Nr. 708281 might be incorporating a serial number, but it is being coded. Not saying that my example is valid - please imagine that it actually was 81 or 82. The rest may contain information, but certainly not that 8281 have been produced or 708. An option could have been that it carried serial number 8.


The circular Bakelite cap is covering the central coaxial connector

The cap just right of it covers the 220 V (dc?) switching voltage. The two Bakelite caps on the far right and left are both covering two coaxial connectors. I don't know exactly the lobe-switching sequence, but quite commonly used was 25 Hz.

The Fe (cover) housing is typically for latte 1943/44 techniques, where Mg and Al were becoming scare materials. Fe was regarded in this, as well as in many other cases, good enough for its purpose.


The connector for the 220 V lobe switching relay (Bakelite cap being removed)


Lobe-switching principle

When the switch is directly connecting the right-hand antennae, the left-hand antennae is being connected by means of a so-called "Umwegleitung". This is a coaxial line which is delaying the signal fed to or originating from the Wassermann M antenna system. The next period (sequence) the system is directly fed onto the left-hand system and now the signals from or towards the antenna-system is being delayed in time. Resulting in two main antenna lobes in either direction. The result of this technique is - that one was no longer DFing on the main central antenna pattern (searching for maximum signal strength, this actual bearing point is by far broader (fuzzy) hence, less accurate) but the sharpness of the lobe allowed now a far better determination of the actual bearing azimuth. Being in the centre in between the two antenna lobes.


The "Umwegleitung" (delay line) is clearly visible

The central coaxial system is each half switching cycle connected onto one of the left or right coaxial connectors.



The relay system is on the left-hand side

The switching mechanism is clearly visible. Maybe less visible is that the switching finger on the lower side is entering the central (left-right) switching space.


Watching through the window we see two switching contacts


On 28 February 2011

We have added an item which hardly will attract the attention of whom interested in the history of technology.


So-called Netzfilter or electronic noise suppressor. Produced by AEG in 1940, type MSG 201/1


The inside the mains filter

The Germans took very great care in respect to "keeping noise off the air".


A very important aspect is how noise suppression is accomplished. An important aspect is that the leads of the filter capacitor(s) is being kept at the lowest impedance possible. You will hardly find German commercial filtering where ground is connected onto by means of separate wires. 99.99 % of all measures taken were such - that the capacitor-metal-housing (block) was directly mounted at and thus connected onto a frame or chassis. Especially Siemens & Halske was 'a master of art' in noise suppressor- and filtering techniques!



On 3 March we have attached a new series


NiCad battery maintenance set

Nickelsammler Zubehör


The three metal containers of which two are being filled with 'aqua dest' and one with caustic potash lye (Kalilauge)


Testing set as to measure (weighting) specific gravity


Some amount of the battery liquid is taken from a battery under test and being checked for its actual specific gravity value



EO 281/II (14.62 - 102.8 MHz) receiver

This receiver was used, among for other things, in the early days for watching British radar signals, for instance, at beaches. Such as for listening into Chain Home (C-H) transmissions. Its concept was kept simple it, nevertheless, was a full super-heterodyne RX.


The three interchangeable coils were accessible from the left-hand side (compartment closed)


The coil section accessible

I purchased first about 1976/77 a box of these coils, at that time I did not knew for what system it was meant for. Some time thereafter I could swop this receiver without having any coils, which was reducing its wanted value considerably!


The left-hand side of the internal receiver

It employed the universal valve type RV12P200 in all stages. It could thus be fed from a 12 V battery and a HT dry battery pack; as well as from a mains power supply or from a voltage convertor (Umformer oder Zerhacker)


The right-hand side of the receiver

The symbols 'EO' is typically for C. Lorenz products.


An EO 281 coil for range 1 to be employed in stage II



The transport case of Fu 30a

This set was measuring the off-set of direction finder systems. As well as the north meridian


Beladeplan für Transportkasten Fu 30a. Richtgerät für Funkpeiler


On the right-hand side we see the optical system, which was placed at distance from the DF site. The optical system on the left was placed in the centre of the DF loop and was directed such that it watched towards the right hand set (some DF loops were fit with a special central mounting pin). Both were optically heading for the opposite white-black-white fields. When these where in their optical centres both were exactly pointing for one another. The right hand set is having in its bottom section a compass which could be observed through a glass window. Both modules possessed an internal light bulb which allowed operations during dark times. The blue light was then pointed at instead of the W-B-W fields, which couldn't be seen without sufficient light.


Das Richtgerät für Funkpeiler Baumuster SK V; made by Ertel München (Munich)





L-Empfänger (L = Leitstrahl); serial number 0004, year 1940

The frequency range was equal to the one used for tank communications (27.2 - 33.3 MHz)


The Leitstrahl receiver was more or less conventionally constructed though, still quite compact. Its was designed and manufactured by Kapsch in Vienna (then part of the Third Reich). All 6 valves were type RV2,4P700. Its principle was based on super-heterodyne


The two boxes each having two holes in it are the IF transformers. This might indicate that the RX had a single IF amplifier stage. The valve is mounted in between the two cases. The headphone was connected onto the bottom end of the housing box, where also the power connections are mounted



The Leitstrahl-RX is carried on the breast of the operator. On his back he carries the battery pack


The 120 W transmitter system based on the AS3 type (the central module having two moving coil meters). It concerned a ground based beacon transmitters meant for aerodrome homing beacons


The directional antenna system

These two latter illustrations were derived from the wartime navigational symposium held in Landsberg-Lech on 23-24 March 1944 (all papers are available from this main page)particularly contribution number 19. This very noticeable gathering (Tagung) was very well regarded in post war days in the UK and abroad. There exist even an integral translation of these conference papers.


How did it actually work?


Please consider first my paper on Navigational Aids (pages 6-9) from 1997 held at Bournemouth University during the annual CHiDE Symposium.     Let us remember the principle of the Lorenz beacon transmitter placed in line with the landing strip. At distance the landing beacon could be received. The continuous beacon signal was transmitted in a special manner. The antenna pattern was switched alternating in such a manner that two complementary beaming-signals were generated. Symbolised by the Morse codes A and N. Those acquainted with Morse codes know that this is respectively:  .- and -.  When one is just at the virtual centre line of the main antenna beam an operator will hear in his headphones a constant (particularly modulated) tone. However, when he comes out of this navigational path he will hear dots or dashes.     The ground based Leitstrahl (directional beam) was exploiting this principle. As long as the soldier kept himself on his virtual path a constant signal was being noticed. When he became out off direction he was informed onto what direction he was out of path (dashes or dots). The Lorenz beacons were used such that an aircraft was actually homing onto to the landing strip, whereas in this case he was walking away from his guiding ground transmitter signal.     However, I understood that the Leitstrahl system was tactically not a success and the Germans might only have used it for a few occasions in the 1940 West Campaign. I obtained our set about 1976 in Denmark. Why it was found there I cannot judge.



On 8 March

I have attached some new detail photographs of renewed exhibition in the rear hall.


Please notice, the boxes on the front table have been replaced by a new exhibition in which we would like to show measurement gear, and especially what technical means is inside. The black boxes in the rear of the table is shown on the next photo "Inside out"


The optical data recorder type LOG1 is a recorder which is storing its (measuring) result onto a broad film tape. 4 channels are being handled (monitored) by means of so-called 'current-loop' moving coil devices. These items are responding, in contrast to normal moving coil meters, onto alternating currents up to a kHz or even up. LOG1 was meant for test-flight-data-recording. Instead of having pointers a miniature mirror is coupled with the moving coil and a light beam is being deflected. A (half) cylindrical lens is projecting the results onto the (slowly) moving film tape (the film cassette is on the left-hand side of the main unit). The film transport speed could be selected. It could measure simultaneously, for example, temperature of an engine and watching the strain or pressure in some aircraft part or component and/or measuring vibrations. The flashing lamp, which gave the timing markers, is the Al (Ni?) like cylinder in front of where we just are looking at (in the centre). The mechanical timer unit is shown on the right. In the background we see what is inside of the S&H noise search and noise level measuring apparatus


Inside the LOG1

It is showing the complexity of this apparatus. Please notice the slit (Schlitz) of the flash-light far down on the left (providing the timing markers at the data film). Several mirrors are reflecting the flash pulses towards the film cassette.


LOG1 film cassette being opened

Detail view of the current-loop-galvanometers. The small rectangular silver like miniature mirrors (visible through the two left-hand lenses) are each mounted onto the miniature moving coil. The upper strip with the circular holes is carrying (holding) a broad flat mirror, which is conveying the movable light spots towards the next mirror. The very tiny mirrors are necessary as these have to respond onto several thousand movements per second, or at least onto some hundred movements per second  



Type number label of the R&S (PTE) power signal generator type SMLK (Leistungs-Meßsender)



SMLK front panel

One have to think of maximally 10 V (notice the previous label).


Shown is the HF compartment of the R&S (PTE) power signal generator type SMLK

Below we notice a pair of RD12Ta valve (Lorenz Napfröhren); followed by a pair of EF14 (Stahlröhren - 'steel-valves'); the upper valve is type RD12Ga which is a UHF diode and has to measure (controlling) the accurate output signal. The symmetrical trimmer placed in between EF14s and RD12Ga is a fine tuning trimmer, which can be adjusted (set) from the front panel. This compartment can be closed by means of a sliding lid, as to maximise screening-off from environment



WIQ Wellenmesser (wavemeter)

The device on top is also a WIQ


WIQ now looking at the RF section

The ring coil (Ringspule, please notice page 9). The brown rectangular quartz for 3030 kHz is original, but should be replaced by a 100 kHz type. The 4 valves involved are all type RV2P800. The 'Ringspule' is of very high quality and provided in another concept (WIP) an accuracy of 0.005%.

WIQ controlling section

It is still hardly touched (only a single resistor and capacitor being bridged)



Prüfgerät type 105. Most likely built by the Gema company, though, according the documentation this was done on behalf of: 25. (techn.) Ln. Vers. Regiment Köthen Anhalt Fliegerhorst. Date of document 3 November 1944. I guess, that it was generally meant for Freya and/or derivate radar equipment. It provided a signal source for 6 - 16 MHz as well as for 50 - 70 MHz. In the doc. is mentioned that its harmonics reached up to 700 MHz


PG105 looking from the rear inside, with screening plates being removed.

Up on the left the oscillator section for 50 - 70 MHz and on the up far right the oscillator for 6 - 16 MHz. The latter was most likely meant for covering the Freya IF band. In the centre I guess the signal leveling stage. The right hand oscillator coils is of the well known silver deposited on a ceramic-cylinder type. Just above it in a semi-separate compartment its filter section which had to suppress HF from the rest of the apparatus.


Since 15 March 2011 we have continued with an extension page called: Exhibits details 2



 Finally our:

Berlin radar considerations

This Berlin related contribution does not entirely reflect what we actually possess, but is attached as it forms a subject of which we have some parts, like the Berlin PPI display unit SG224 and the pulse forming network LK1 (Laufzeitkette) and the pulse step up transformer.


After I presented my paper to the CAVMAG 2010 conference held on 19-20 April 2010 (The German Wartime Struggle to catch up with Allied Power Magnetron Technology), I discussed with Hans Jucker the properties of the pulse-forming-network type LK1. Which actually must have been a copy more or less of the same circuit found in the remains of the Rotterdam apparatus (H2S early version). He soon calculated the electrical energy stored in it. Its title is: Modulator of the German Berlin microwave radarset (equals GAF type: FuG224 or Berlin type A). I obtained these parts about 1980 from late Ebbe Peedersen of Denmark. Putting all facts together, I guess, that it remained from dismantling of a FuMO81 radar set which was captured by Danish authorities in 1945. Whether with or without British approval, I don't know. I obtained these components as it fitted to my future strategy. Although, I myself never could have foreseen that it ever was possible to swop the very rare Berlin radar PPI display unit (SG224). And showing it this way!

We very much would appreciate to find other Berlin radar modules or pieces


Pulse forming network type LK1

Please see for its circuitry Hans Jucker's paper


Berlin PPI display module type SG224

This module was obtained from Britain, some years ago


The following Berlin radar related photos, is not part of our collection, though being meant as to show how some modules look like


Berlin A type transmitter/receiver front-end


Feld II of the Berlin A system (serial number 391)

The upper module is like the previous photo, the lower section contains the modulator. In contrast to British H2S, it does not have the pulse forming HT section integrated as this was by German redesign an integral part of the transmitter section, which is from a technical point more appropriate, as the 10 kV pulse signal does not have to be fed by means of an external HT cable.


Feld I


Feld I (module 1)

The timing (waveform generator) section including the IF stage. This module is the top one left on the last photo



Control box of the Berlin radar system, its main function is to interconnect the system wiring incorporated in a single unit


Some time ago Horst Beck did send me the next photo


VK224, apparently the Naval version, Thus representing the same function as the previous module

This device was offered to Horst Beck some years ago though, he has rejected it (maybe too expensive?)


Berlin radar, mounted at a frame. Most likely of navy type (FuMO81 = FuG224) This type of mounting often was called: Prüftafel (Testing rack). I guess, it would have had then designation PT 224

Although, the text on top of the mains switching box indicates 230 V 50 Hz, this might have only controlled the voltage convertors for 80 V 500 Hz, like was used for H2S as well. Curious is, that the Germans, like in most other continental countries used 220 V 50Hz. Probably tailored here for British circumstances.


We would be very pleased to get any kind of feedback from those who have or can add additional information.

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