Jagdschloß A (Jagdschloss A)

FuG 404

German PPI radar system


Technical training manual for radar engineers

Ln Schule 8

Lehrschule für Fernmeldetechnik


November 1944

2. Auflage (second edition)

Oberkommando der Luftwaffe


Ln.-Inspektion - 6. Abtlg.

All together 317 manuals had been printed

PDF, 4.9 MB


This page being extended on 4/5 November 2015

Status: 5 November 2015

First extension called:- A!


There existed two wave ranges, let us call them respectively A and B: 120 - 157 MHz and 157 - 250 MHz. According to a source, serial production started late 1943. Up to April 1945 were: 18 systems of wave region B and 62 of range A*. Thus, a total number of 80 systems were delivered to the German air defence organisation (Luftwaffe). We don't know exactly how many system became finally operational. *Frequency range A overlapped the regular Freya wave-band.


Die Jagdschloss-Anlagen stammen in ihrer Weiterentwicklung von der Firma Siemens (S&H).

Jagdschloss A

Dies ist die zur Zeit ausgeführte Anlage.

Jagschloss B (geplant)   Es bestand von Anfang an der Wunsch, das in einer Gerätestellung gewonnene Luftlagebild an eine zentrale Befehlsstelle zu übertragen. Für die Übertragung des Bildes sind bei der A-Ausführung drei Komponenten erforderlich und zwar ..... (partial text of page 5


Jagdschloss radar antenna-array, seen from the rear. This typical brick-stone building may have been (sometimes) on top of an 'underground bunker'



Keywords: Blockschaltbild Jagdschloss B mit Übertragungseinrichtung; Sternschreiber; Prinzip der Synchronisierung bei Jagdschloss B; Blockschaltbild Jagdschloss A mit Übertragungseinrichtung; Übersichtsskizze Anlage Jagdschloss B; Übersichtskizze Anlage Jagdhaus; Kennung (IFF); Duplexbetrieb; Bildübertragung; Allgem. Meßprinzip der Rundsuchanlagen; Stufenschaltbild der Rundsuchanlage Jagdschloss A; Verdrahtung f. Jagdschloß; Antennen-Anlagen; Aufbau der Antenne; Speisung der Antenne (Kabelplan); Einheitsfeld; Breitbanddipol Ortskurve; Änderung der Strahlungscharakteristik; Kabelplan der Antenne für Jagdschloß; Strahlungsdiagramm; Der Breitbandübertrager; Übertrager 70 Ohm auf 70/2 Ohm; Frequenzgerät; Wirkungsweise; Bedienungsanweisung für Z Gerät; Prüfvorschrift für Z Gerät; Prinzipschaltbid Z-Gerät Phasenschieber (delay line); Zusatzgerät zum Z-Gerät Wirkungsweise Kompl. Scahltbild Zusatzgerät Prüfungsvorschrift; Beobachtungsgerät, Wikungsweise; Im OB-Teil; Prinzipschaltbild Beobachtungsgerät; Gerät R, Einsatz RH101, RN105, RJ102; Prinzipschaltbild R-Gerät; Kompl.Schaltbild Hochtastgerät (20 kV zum Sender); Kompl. Schaltbild Steuerteil; Sender mit TS41; Vorläufige Prüfvorschrift für das Gerät Eibsee mit Gittertastung;  Breitband-Simultangerät Rießersee (Riessersee) T/R section; Riessersee 2, Riessersee 3; Prüfvorschrift für Riessersee I, SD6; Der Breitbandempfänger, Technische Angaben, Beschreibung D Zwischenferquenzteiles; EEF50 (EFF 50) at the receiver front-end; EFF50 data sheet; Radar receiver Kreuzeck, Prüfvorschrift für das Gerät Kreuzeck, Bedienungsanweisung; Sternschreiber PPI display unit technical circuit description; Blockschaltbild Sternschreiber; Gleichlaufübertragung, Synchronisierung; Lichtsirene, Photozellenverstärker; Drehstromverstärker; Impulsgerät, Aufgabe, prf 500 Hz, EZ150(double rectifier); Bildwähler, Synchronisierung; Aufbau der Kennungsantenne; HF-Verdahtung des Standes; Antennen-Antrieb; Komplette Röhrenbestückung-Jagdschloß; PPI CRT type LB40 m/3, HR2/100/1,5                


Half section of the Jagdschloss antenna array. Its antenna field is horizontally polarized, whereas the vertical radiators in the upper section belong to the IFF system


Fine range measuring set-up of Jagdschloss (Ansicht des Gerätestandes Deckel geöffnet). IFF is the receiver for "Identification Friend or Foo" (code-name "Gemse"), RX is the radar receiver "Kreuzeck", with its front-end (see page 83). RD is the fine-range display CRT, the three clocks on its right indicate mechanically the distance(range) marker (regard also report TME 11-219). Not quite clear, but the magnifying lens had been pulled (fixed) upwards




The PPI display unit (Sternschreiber), cover-plate being removed. The CRT had,  presumably, a screen diameter of 40 cm (LB40 m/3)



"Landbriefträger", shown is the carrier interface which was used to transmit radar (video)signals onto remote Command Stations like to an "air-defence operation centre" (Ansicht der Übertagungsanlage). The data was sent via broad-band cable facilities


At the other end of the line was the receiving-end of the radar-data-transmission system, also equipped with a simultaneously operating PPI display (Sternschreiber)


Shown is: the broad-band Jagdschloss transmitter on the right. Left of it is placed the (automatic or simultaneous) "transmit-receive" switch (T/R). This probability maybe an older version




RAF offensive on Berlin with approximately 400 aircraft, on 30 January 1944. The circle constitute the 100 km range marker, the gap in top indicates 'geographical north' (Nordmarke)


Hans Jucker kindly referred to this contribution:

Dear Arthur,


the latest increase of your  website, the  “Lehrunterlage Jagdschloss A”  for the German VHF Surveillance Radarsystem as well  as the Technical Manual 11-219  are both very interesting authentic papers for seriously interested fellows in radar history. 


Please let me introduce some remarks according the content of the papers:


A former Siemens & Halske representative held a couple of years ago an interesting lecture about the development of the German WWII “Jagdschloss” surveillance radar. He pointed out then, that the basic idea for the plan position representation of radar information (if the slant range and azimuth coordinates of the various targets in the field of view are represented) was borne 1936/37 at the Gema company, Berlin. However, the most restrictive reason for the realization of surveillance radars was the limited performance of the early radar transmitters and receivers.

In opposite to searchlight radars with the typical pencil beam the surveillance radar needs actually a beam that is fanned in the vertical direction, if aircraft are to be observed. So, for a similar power density at the illuminated coverage, the radiated energy must be higher than for the searchlight radar. However the power capability of the Freya transmitters couldn’t be increased without a time consuming new tube program.

Therefore occasionally the development of the “Jagdschloss” Surveillance Radar, Siemens & Halske tried to compensate the insufficient radar performance by an improved receiver. It was planned to use the new Telefunken LV 4 wideband double pentode for the rf preamplifier and the first mixer of the receiver. However, Telefunken had problems with the development of the LV 4 double pentode, so after all Siemens & Halske used the Philips EFF50 for the receiver front end of the “Jagdschloss” surveillance radar.  .

 The technical manual 11-219 seems to be derived from the original document:


OEMsr 411 - 95 , Survey of German Radar from the Countermeasures Point of View

 Originated by the Radio Research Laboratory of the Harvard University, September 4, 1944  

operating under Supervision of Office of Scientific Research and Development; National Defense Research Comnittee, Division 15 of Radio Coordination.

 It seems to be an updated version of the Document OEMsr 411 – 95 !

I havn’t found before any information that an alternative hard tube modulator (with the RS 323 tube) exist for the FuG 200 Hohentwiel airborne radar ?


My best wishes


Hans J

I would like to add: That already Chester W. Rice of GE in the US dealt with a PPI like system. And, would like to say: "PPI was alerady in the air:. He described a PPI like radar in 1936, be it without range measuring in the PPI display, as this was read-off a display panel (regard my contribution Radar II.)  



In September 2011 we have obtained from the UK the original Jagdschloss transmitter module


Jagdschloss transmitter codename Eibsee

Please consider our:  new dedicated transmitter webpage to this transmitter


Prinzipbild - Jagdschloss

Ln.- Ausbildungsstab 2

Zeichnung B/F 231 date 26.7.1944

Please click on this drawing as to open it in pdf

Please notice that you can print the full schematic at a single A4 sheet by using the option in "Acrobat Reader " print what you see at your screen" thus befor doing this adjust the size of the schematic at you computer screen!


List of Jagdschloss codenames (Tarnnamen)


When we consider the valve types engaged we can see that only LS50s - LV1s - TS41s - EF14s - SD6s and RV12P2000s are being employed (neglecting the single REN901 triode). The advantage is obvious, because service stocks could be kept very rationalised.



On 5 November 2015

After having worked for quite a while on the Wassermann radar Survey, we got material that also does make sense in respect to Jagdschloss radar applications. Because, both equipment were more or less equal; such as the Siemens designed high power provisions for modulator and transmitter devices. Their antennae concepts differed completely.

A quantum leap was initiated by a batch of documents and photos on behalf of Mike Dean. The main bulk of his documents are related to recordings made during British Operation Post Mortem; held in Schleswig and Denmark during an exceptional exercise (late June and early July 1945); where British bomber streams were confronting German military service personal - operating their genuine equipments again, in post war days.

The Germans in Denmark and also Schleswig surrendered without large scale destructions. Therefore most systems were still intact and operational. German military personnel were brought back from prisoner camps to their former site.

A series of Bomber Command Raid trails had been simulated and the (German) responses monitored by British observers.

Offensive trials were accomplished, some with- and without jamming. Don't underestimate this endeavour as sometimes 200 and more aircraft have been engaged in single trial!

During these late June and early July 1945 exercises - photos had been taken as well. And, of course, a range of brief reports being produced.


Let us first consider a schematic block diagram of a Jagdschloss system, once hanging on a bunker wall, in Schleswig.


For us - is of first interest the left-hand side - second block series from above

Please click on it as to get in better quality and PDF

(111 SC 269061 - "US National Archives" courtesy Mike Dean)


Let us secondly consider the second module: Hochtastgerät


This is what it was about

You can click on it to obtain a 600 dpi PDF version


Viewing the insert from another perspective

You can click on it to obtain a 600 dpi PDF version


Its schematic looks simple, but its concept was quite clever

For those interested in an extensive Survey on this subject - please notice the according Wassermann chapter.


Among Mike Dean's documents was a tantalising photo which I never have seen before.


The high power broad-band TX version, fit with a pair of TS 60 valves

Photo taken in the Danish Jagdschloss station at Skagen

(111 SC 269071 - "US National Archives" courtesy Mike Dean)

Down on the right-hand side we find just the two pre-driving-pulse stages of the TS Gerät

This - pre-power-stage drives the Hochtastgerät; or power modulator. The latter providing   100 - 300 kW (22 - 30 kV) pulses.

Almost every GEMA related radar system relied upon a 500 Hz PRF - which provides a (radar) pulse each 2 ms. When we estimate that pulse duration lasted, say, 2 µs the pause time was: 2000 - 2 = 1998 µs.  

The power modulator output transformer provides these pulses - which is to be fed onto the transmitter module Eibsee, these pulses constituting the anode voltage (technique known as anode modulation). I have to admit that I am not sure whether the high power TX fit with a pair of TS 60 valves did carry the same code-name designation:- Eibsee. (a guess: maybe Eibsee II or that like)

This module might have been implemented in the last stage of the war. Because our TS 60 sample made by Siemens by Gema design was mentioned - as well an acceptance date somewhere in January 1945. My sample was obtained from Ebbe Pedersen in Denmark in the second half of the 1970s.

Please notice left of the transmitter/pre-modulator housing - the open T/R unit or Simultan-Gerät. Its appearance differs a bit from the original Reißersee I apparatus.

Another interesting photo is found among Mike Dean's materials


Showing the transmitter set up (Station Skorping, Denmark)

(111 SC 269092 - "US National Archives" courtesy Mike Dean)

Let me explain from left to right:

The Simultan or T/R apparatus

The black box left of it and on top of the next module - is a (typical Siemens) matching provision between the TX output and the T/R apparatus.

On the far right - a couple of R-units or power supplies; providing medium and high voltages up to about 11 kV each.

The TX differs from the previously shown set fit with a pair of TS 60s.


The 'insert' is similar to the unit on the left-hand side (Shown an Eibersee TX fit with a pair of TS 41

How do I know that it did not concern here a similar TX module than the one showed previously fit with a pair of TS 60s?

Please compare both, you might recognise that the TS 60 tuning provision is down in the centre, whilst the TX shown above and foregoing do have their tuning provisions on the left-hand side.



continuing with the foregoing photo:


Underneath the TX module we encounter the modulator pre-stage.

Right of it - my hypothesis:- the small cube like unit - might contain the Hochtastgerät (high power modulator)

However, what is irritating me, is, the fact that I cannot see any cooling provision.


Right of this module (with the open-wire antenna connection on top) we encounter the I.F.F. transmitter (F.F.K.) unit.

According the block diagram - the I.F.F. transmitter being fit with a pair of TS 41 valves. This implied, that the I.F.F. signal power was quite strong (about 8 kW pulse output).

Providing a capture range likely exceeding beyond the Jagdschloss capture range for at least 100 km.

Please bear in mind - radar signals bouncing on the surface of a flying object: - only signals that touches just a surface perpendicular (at 90°) - having a chance being detected by their radar system again; whilst the I.F.F. signal being received by the I.F.F. receiver front-end - being amplified and retransmitted with pulses of several 100 watt. The I.F.F. capture range is therefore beyond optical range.


Continuing again: 

With in the lower compartments the medium power modulator stage. Probably using grid de-blocking pulses, less effective, but given the simplicity of outfit, just providing sufficient antenna power.

Both - the radar TX as well as the I.F.F. system were driven from the same time-base unit Z (PRF 500 Hz) albeit that a special provision was existing by which means the additional I.F.F. system-delay could be - more or less - brought in line with the Jagdschloss radar screen presentation. An I.F.F. signal from its very nature lags always behind the (surface) bouncing radar signal, due to the transient time within the (electrical) aircraft I.F.F. transponder.

A separate I.F.F. transmitter was necessary, because the German I.F.F. receiver within a FuG 25a set, was only capable of picking up signals in the spectrum of, say, 121 - 126 MHz (wobbling through this spectrum). This was in the beginning equal to the GEMA operational spectrum (neglecting Seetakt). But requirements changed and the radar spectrum was widened in the course of history up to about 155 MHz.

The FuG 25a I.F.F. transponder responded (towards ground) at about 155 MHz. But de-coupling might have been sufficient owing to the fact that Jagdschloss radar operated with horizontal polarisation whereas the I.F.F. system relied on vertical polarisation. 



Maybe of some interest is the construction of a Jagdschloss antenna. Apparently, the Jagdschloss stations was not yet operational

Caption: Jadgschloss antenna Skorping Denmark 1945

(111 SC 269084 - "US National Archives" courtesy Mike Dean)

The upper rectangular section contains the I.F.F. (F.F.K) antennae vertically polarised.

This was done because the I.F.F. antennae generally had been mounted vertically underneath the fuselage.

This antenna was likely operating split-beam, so that it was possible to provide exact I.F.F. bearing.

The wide span antenna group was using horizontal polarisation. All dipoles were of the wide-band type, allowing operation between 115 - 155 MHz. Only the T/R or Simultan apparatus had to be tuned - as well as, of course, the transmitter and receiver. 



Viewing a section of the Jagdschloss antenna rig of the station at Skorping Denmark

(111 SC 269085 - "US National Archives" courtesy Mike Dean)

A few days later I was preparing an extension of our Wassermann page, this time based on drawings provided in a Danish post war report.


Showing a drawing of a half antenna group used in the Wassermann antenna array

(post war Danish report, courtesy Mike Dean)

Both Wassermann and Jagdschloss radar systems relied heavily on Siemens technical support.

The antenna techniques may be equal, and we may consider that the "Balanceringsfirpol" stood for 'balancing four pole' we have already explained that such device was known in the Anglo-Saxon world as balun. In Germany, known as Sperrtopf.

Its technical construction differs a bit from the technique used in Mammut antenna systems. I assume that you will understand how it was done.

I do wonder however, apparently dealing with a wide band system between 115 and 160 MHz. And the Sperrtopf is having a ¼ λ system incorporated. However, ¼ λ  means a quarter wave length; though at what wave length?

In someway or another proper functioning is only possible at a particular wave length. Some techniques do have countering physical phenomenon, but I cannot find how this might have been accomplished.

I assume that the equilibrium being chosen somewhere in the middle of both maximum deviations; thus at about 137.5 MHz.


However, continuing:

The reflector being made of simple 'chicken-wire'  

Maybe not well visible, dipoles being mounted ¼ λ in front of the chicken-wire reflector screen.

Broadband dipoles can be simply recognised by their quite heavy diameter, sometimes being flat, but still - the length-diameter ratio is smaller than is in case of narrow band (wire like) systems.


An example how antennae can be grouped together

(Wartime conference paper: ZWB- Berichte, look for Zinke's and Roder's contributions)

The upper example represents the older narrow band group, whilst the lower drawing section shows the broad-band application.

Please compare the - in the centre of the lower left-hand drawing the circular device and draw now you attention onto the foregoing photo. It is clear that both devices are similar. Such device was called: Sperrtopf, also known as balun (balance - unbalance).

But a Sperrtopf provided a balance - unbalance transformation with an impedance ratio of 1 : 1.

Often 70 Ω : 70 Ω, but also other coaxial line impedances have been used.

The main advantage of Sperrtopf technique, was, that line-phase was clearly determined, what is not always the case within regular balun provisions.

This became highly significant when complex antenna arrays being dealt with. Here correct group phasing is essential (beam forming).


To be continued in due course 


Please consider also, or return to: Kreuzeck-Survey

Please consider also the new: Jagdschloss TX and system page

Back to or proceed with: Report TME 11-219

Back to: Handbooks papers and product information