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German directionfinder Peil G6.

Direction finder receiver EZ 6

“EMPFANGER ZIELFLUG”

Overall description of the receiver as a direction finder.

This is a receiver, part of the Geman “PEIL G 6″ aircraft installation called  “Peil Gerat 6″.

It was used for navigation/directionfinding purposes in large aircrafts like the Heinkel HE 111, Junker 88 and so on. It was common for EZ6, to be combined with the Fug 10, where it would have b

een placed instead of the E10L receiver. This was called the Fug10P (Peil).

There are 3  frequency bands: 150 -300 Kc, 300-600 Kc and 600- 1200 Kc.

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Photo above: front of the receiver

  • Upper left knob: A2 is AM, Eich is calibrating the frequency, A1 is BFO is used by navigating, Bandbreite is making the MF smaller.
  • Upper right knob: Entrubing is cleaning the signal from “humm etc.”
  • Middle knob: tuning the frequency.
  • Lower left knob: gain controll.
  • Lower right knob: arrow is navigating by a double needle instrument type AFN2. Circle is “Rund Empfang, frequency band 300 -600 Kc. Communication purpose as a replacement band for the E10L.
  • Lower middle: connection for headphones (left) and test entrance for test meter PV10 for measuring the internal voltages.
  • Small upper right panel: Behind the trim pot for calibrating the frequency scale.

The inside of the EZ 6 receiver.

Note the text on the pictures for removal of the various part blocks and connections.

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The front with cover panel removed.

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The block units from the receiver from behind.

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A connector of a unit.

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Here to be seen the contacts of band switch.

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Right the opened oscillator unit.

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Oscillator case with circuit removed.

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The removal of the oscillator ceramic plate. The green points are the data, where the wires, comming from behind the ceramiec plate, have to be desoldered.

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The three wave band coils of the oscillator. Above in the picture, the metal cover of the coils.

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The three coils explained.

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The connections of the coils, the grid, anode and coupling coils. Very handy for measuring the coils.

Temperature compensation for to stabilise the frequency of the oscillator circuit of the EZ 6.

All the components of it are mounted on a ceramic plate as a printed circuit, which was very revolutionair  in that time, nowadays very common. This has a very good effect at changing wiring capacities, due to warming up of them. Also mechanically very stable to heavy shocks.

Other provisions were these ceramic condensers in parallel , which have a temperature coefficient control. When they get warmed up by the air in the small cases of equipment, their capacity values changed that way, that frequency stability of the oscillator is improved.

These special condensers, you can see in the picture above, the green and brown condenser blocks.

On the printed circuit plate of the oscillator ceramic plate in the left side of the picture above, you see these green and brown  condenser blocks. All ceramic  condensers, in parallel, are placed over the the inductancies  in the circuitry.

About these condenser blocks, there was another type with ceramic ones with different specifications . Different from these of the temperature coefficient types.

It is so special, that I like to tell something about it.

One is a special, great type of ceramic condenser, which proof the great knowledge of German engineers in that time. Consider, it is now more then 70 years ago!

These were made by the German manufacturer Hescho, who patented it, and made also the ceramic coils holders and variometers.

The ceramic condensers are very special made. In fact, they are very bad condensers with a big dielecric loss with a particular temperature coeficient.

The principle:

Let us look at the internal capacities between the anode and grid and between kathode and grid, eg.  Cga and Cgk,  of a radio valve. When the radio valve is warming up, and getting warmer and warmer, when it is delivering power, the anode dissipation is increasing, these capacities are changing, the value is getting higher. So the frequency of the oscillator is changing and getting lower. Characteristic curves and values are well known for each type  radio valve.

Now we look at these special ceramic condensers. When HF energy is applied on these condensers, by the energy of the oscillator,  the dielectric electric losses of it changes by heating up of his body, so the value of capacity getting lower.  Hescho managed to measure that amount of dielectic loss in these capacitors. so they could produce a large variety of different losses factors  in the capacitors very accurate.

 That is just what we need to compensate the frequency change, established by the warming up of the valve , so the anode, by the increasing anode dissipation. This proces is acting much faster, then the influence  of the temperature compensating material, in circomstances that the valve is switched off, so cooling down, and later switched on again. Consider, that the remainig heat in the cabinet of this valve is still reaching the temperature compensation material, while the valve has been already switced  off for a while.

So they made the curve of  these combination of condensors that way, by putting several of these condensers in the circuit, that it is compensating the changing valve curve. So frequency stability, needed in such circumstances in the airplanes, was increased well , especially in these oscillators. Note that the German equipment, especially transmitters, were not crystal controlled by lack of crystal material, which had to come from abroad and was of course not delivered almost in that war time.

But these condensers were probably only made for oscillators, not crystal controlled, of transmitters.

You can see this arrangement in the various transmitters for navy, the LO40K39, the MOPA transmitters of the FUG 10, S10K and S10L. Even, I saw it in the oscillator part of transceiver FU Sprech- f of the army. But these were probably only condensors with a temperature coefficient. In these MOPA transmitters of the FUG 10, this stabilsation method is most effective. The heat is much in the transmitter cabinets. The oscillator stage, a RL12P35, had to deliver much driving power, so getting very warm, by his big anode dissipation, for driving the power amplifier of 2 RL12P35’s, to let this amplifier provide 60 watts on CW. Below a picture of the condenserblock in a S10K transmitter. In my working FUG 10, the frequence stability is amazing, while the transmitter cabinets are pretty warm. The oscillator is of course not crystal controlled!

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The condenser block of the S10K transmitter. At the right, a kind of printed circuit on the ceramic base.

I don’t think these condensers with that dielectrice loss were used in the EZ 6. Because it makes no sense. The oscillator in the EZ6 uses a low power valve, the RV12P2000. It delivers low energy to the mixer stage. So warming up of the anode is limited, so his internal capacities. But it might have been? I don’t know.

After the war, this manufacturing method of this special condensor was lost and forgetten. A synthisized module was used in oscillators. The frequency stability of them, depended on a crystal controlled reference oscillator. In fact a pity, but it worked well.

De EZ 6 as a direction finder.

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Here the EZ6 receiver  as my “Peil G6″ installation. Just at the right above a controllunit. With the switch you can do an automatic DF ,with the amplifier V6 just below the EZ6 and you can do a DF by hand, using the big knob on it by turning it to the left (L) or to the right (R). The DF antenna will turn to the left or right .Also the speed of the motor can be tuned. Right below the rotarytransformer U11 for the powersupply. In the middle the DF instrument type AFN2. Just all above  the motordrive for turning the DF antenna. Also seen the sense antenna. The complete system is a homemade version, except for the PRE 6 motordrive.

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The AFN 1 instrument. The vertical needle is pointing to the dot, when the airplane is at course. The horizontal needle is for the signal strenght of the beacon transmitter. Tuning at maximun signal of the receiver tuning.

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The DF antenna system. Above the sense antenna (homemade), below the PRE6 motor  drive unit.

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The PRE 6 motor and drive unit above and the ferriet antenne, just below the sense antenna, which is homemade one, by lack of the original one, but works very well.

This whole installation (certainly not original) is setup by my own and in fully working condition. The receiver is fed by the U11a by 24 volts DC. You can find the correct direction by rotating the little ferriet antenne  and watching the AFN 1.

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Replica Wurzberg radar transmitter SU 62 D.

Wurzberg Riese transmitter SU 62 D of FuSE 62 D radar.

Wurzberg radar is a German radar system from WW2,  to locate, mainly allied bomber convoys, on their way to targets in Germany. When located, their positions were given to the Nightfighters from a central command station, to intercept them. When they were in the neighbourhood the picked up the convoys on their own radar on board.

A lot of radar systems were spread out over the occupied European countries, coastlines.

Their maximum range was 80 km and the working frequency was about 500 Mhz,  It even had a IFF system, called Gemse, for indicating weather the convoy or plane was enemy or freind. Its use was still in progress, when the allies made radar systems on 9,1 cm with better valves and more power, the magnetron. It took a long time, before the Germans were aware of this 9 cm radar. At the last end of the war, they developed also one, called “Berlin Gerat”. They came aware of it, after a bomber plane went down in the neighbourhood of Rotterdam, The Netherlands.

Also they could detect 9 cm radar pulses at that time, with a socalled “Korfu Empfanger”, so detecting these radar signals at 9,1 cm.

Because I am so interested in all kind of German radar in WW2, also allied ones,  I decided to publish a new post of this matter.

I have only some small parts of German radar in my collection, because it is most difficult, to collect some parts of these devices. They are very rare. But also valves for very high frequencies and magnetrons etc. are interesting.

After some visits to the museum of mr. Arthur Bauer of  The foundation of  German communication and related technologies  in Duivendrecht, The Netherlands, I had the possibility to examine his working Wurzberg radar installation. I must say, I was most impressed of it. Complete with transmitter, receiver, power supplies, units for measuring the  power and a signal  simulation unit,  called artificial target Rebock, to simulate a reflection target on the CRT.

Also the whole system is discribed in his beautiful and professional website.

Because I received some LS 180’s recently , the transmitter valve in this Wurzberg radar, I came to the idea to make a replica of the transmitter only, the type SU 62 D, belonging to the Wurzberg radar type FuSE 62 D.

Not having the idea, to let it will work once, there are so many other parts to be need. Just a replica, but it must be possible to let the heater glowing. Also the the length of the lecher lines are not right, but that does not matter, it does not need working.

This SU 62 D is a special one, because they could change its transmitting frequency some. The range was about 485 – 520 Mhz. This frequency change was sometimes a must,  because of possible interference with allied transmitters.

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The inside of the Wurzberg housing at the back of the telescope. Note that another transmitter receiver (the SU 62 in the picture)  is used, then the type , described in this post. The different transmitter receiver , also Eidechse SU 62 called, could operate at 2 frequencies, 560 en 540 Mhz. The visible A and B on the front indicate it. Furtheron you can see the Impuls generator IG 62, providing the gridblocking of the transmitter. The CRT on the front, a LB13/40 can indicate the controll pulses for the grid blocking signal of the transmitter.

Some below, you can see a original picture of a Wurzberg Riese radar. you can see his size, comparing it with the person in front of it. The reflector dish a 6 meter.  in the focus center , some little dipoles are collecting all the reflected pulses, received by the dish. The dish could turn in the horizontal position, just as well in the vertical position.  On a cathode ray tube, a LB 13/40 you could read the distance to the target in 2 ranges, eg. 40 km or 80 km range.

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Picture at CRT, a target on a distance of 18 km. Picture taken by Arthur Bauer, PA0AOB.

There are still some Wurzberg’s left here in The Netherlands.  For instance one in the Liberation museum at Overloon,which is very complete, and one at the Planetron in Dwingeloo. Both are sadly suffering from weather influences, because they  are placed outside in the open air. If nothing is done, they are rusting away. That would be a pity.

Wurzberg Dwingeloo

Another existing Wurzberg at Dwingeloo, the Netherlands at this moment, 8-10-2015, at the Planetron.

Schotels Dwingeloo a1958

A very beautiful picture  taken of  Wurzberg’s , in use in the past, and the new build 25 meter telescope , at Dwingeloo, The Netherlands in 1956. The Wurzberg in the front moved to the Wehr Museum in Munchen some years ago. The other also is not there anymore. If they were still there, it would be a great acquistion for the whole complex, they could have been restored, just like the 25 meter telescope has been now and is in use now by Camras, a special group, including radio amateurs.

With the help of the Dwingeloo telescope, not  used any more for observations by ASTRON-JIVE,  CAMRAS  people receives the signals for instance of pulsars at a frequency of 403 Mhz with a special Hewlett Packard receiver. A HORN antenne is placed in the focus of the dish. But also other observations.  Also they use it by making”moonbounce” transmissions in the amateur bands.

After the war , most of the Wurzberg dishes  in The Netherlands, were used for observation the H2 gas radio signals at a wave lenght of 21 cm, coming from milk way star galaxies. To get more details in observations,  made by the Wurzberg’s, the 25 meter telescope was build in 1956. This leaded by Prof. C.A. Muller, With the Dwingeloo telescope they could make a picture, just seen from of our earth position, of our Galaxy in the Milky Way. The picture was not to detailed, but the form was good to see, so getting a well impression.

Later on, they build the Westerbork, synthese telescope. Pictures were much better in detail, then the Dwingeloo telescope. Important observations with the Dwingeloo telescope stopped after some years.

Nowadays they almost finished Lofar (Low Frequency Array) antenna system, working on a frequency of 180 – 400 Mhz.

A much more better system, in international cooperation,  is to be developed, SKA (Square Kilometer Array) with antenna systems in South Africa (SKA 1 MID) and West Australia (SKA 1 LOW).

The resolution of SKA 1 LOW resolution is 25 % better then the Lofar system nowadays. Frequency range 50 – 350 Mhz.  Data collect per year 4,9 zettabytes, 157 terabytes per second)

The SKA MID is working at 350 Mhz – 14 Ghz. Data collected in one second is 2 terrabyte, per year it is 60 exabyte.  Enouth to fill 340.000 average laptops every day.

Because the hugh  amount of collected data, special supercomputers are devoloped to make all these data to a detailed picture.

An amazing technoligy.

Now back to Wurzberg again:

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Wurzberg Riese, original picture.

 

 

LS 180

Transmitter valves LS 180. The copper wires at the left are the heater connections for 5,8 -6,2 volt.  The real voltage to be used, is written on the glass of the tube.

At the right inside the anode.

Some documentation about the LS 180 transmitter valve:

Manufacturer Telefunken.

Maximum frequency 500 Mhz.

Type: UHF triode.

Output 8 KW pulsed power.

Input 12 – 16 KW pulsed power, air cooling.

Anode voltage 8,3 KV.

Grid blocking voltage 2,1 KV negative by 1,8 uS. Delivered by the Impuls Generator type IG 62 D.

Heater voltage 5,8 – 6,2 volts by 15 Ampere! Value written on the tube itselves.

transmitter 1

The front and above side.

transmitter 2

The front side. L21 is the output cupper strip, just above the anode inside the valve. Below left, the condenser  C6 and the 3 resistors in parrallel.

The condenser (0,05 uF) and the 3 resistors (16 kohm) in parrallel are in serie with the 8,3 KV anode line. They take care, that the anode only draw current, when the condenser is disloading, when the valve is not blocked by his negative grid voltage. When the grid of the transmitter valve is fully negative at 2,1 KV, the valve is blocked, the condenser is loaded again.  The anode gets no voltage are is drawing a current!. The next episode, the negative voltage on the grid is disappearing, the condenser is disloading to the anode , the valve is drawing current. An episode further the whole cyclus is starting again. It is like a safety circuit for the valve, because when the negative voltage on the grid has been disappeared by malfunctioning , the valve draws only current via the 16 kohm resistor. Note that the current is DC not AC.  This will reduce his total input power. Even when it is dissipating this reduced power, other safety systems will work, so protecting the valve and probably exploding the transmitter unit.

On the right the resistor for the heater voltage, when heater voltage is applied, this wire wound resistor is a bit glowing (I got no other resistor), because of the current of 15 amper is flowing in it. But that will be not a  difficulty. Resistor will not burn away.

Just down the resistor, the supply connector for the heater voltage and the negative grid blocking voltage of 2,1 KV – 1,8 uS, coming from the puls generator type IG 62.

At the left of the casing, you see a small handel. With this handle you can tune the anode lecher and the cathode lecher at the same time to the right frequency, to be used.

The arrow warns you for the very high dangerous voltage. The red and the green stripe indicates, that the equipment was most secret.

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The transmitter is working!!

But not really, only the heater is glowing.  A hell of light is there, all gets very warm too.

I used a voltage of  5, 8 volt by 15 ampere for the heater.

kathode side

The cathode lecher line and tuning, also the heater connection. In the mid of the lecher  line the tuning arm. which is tuning the length of the lecher, by shortcut a part, the quarter wave lenght for that frequency is established.

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The backside. The upperleft connector is used for the 8,3 KV. Also the connection cable (at the right) to the grid of the LS 180 is to bee seen.

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The circuit of the SU 62 D. It is just a  “simple” power pulsed oscillator. You can see the grid and cathode lecher. Capacitor C2 is for the degree of coupling, to let the system oscillate. The output device of the transmitter is only a strip, which is coupled with the anode inside, through the glass, by inductance.

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The original transmitter SU 62 D , a picture taken by Arthur Bauer, PA0 AOB from his transmitter unit during experiment to let it work.

Till so far this post about the Wurzberg.

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FUG 16

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  1. Bordfunk Gerat Fug 16 Z

Bordfunk Gerat Fug 16 Z

This set was build in 1943 by Lorenz.

It is a VHF transmitter, used in fighterplanes like Messerschmitt BF 109. But also the ME 110.

It was remote-controlled from the cockpit. The transmitter-receiver itselves was located in the balley of the fighter plane.

Also it could be used as a direction finder.

 Fug 16 Z front

Picture above:

 Frontview of the Fug 16 Z. Here you can see the servo’s for remote controlling the set. One at the right for the transmitterpart, to change frequency, and one in the mid, for shifting the receiver frequency about 30 Khz, up and down.

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Upperside  Fug 16 Z. At the left the receiver part, in the mid, the LF part and at the right the transmitter part, with 2 valves RL12P35 in the power amplifier stage.

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Backside Fug 16 Z.

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The FUG 16 in the inside of the Messerschmidt ME 109 fighter plane. It was controlled at the pilot seat by a remote control.

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Some time ago I purchased finally after years a original cabinet for it. I only had to buy the cabinet together with a FUG 16 ZY. Which was missing some parts in it. But now the FUG 16 Z was all complete and original. A separate cabinet is very hard to get and expensive nowadays.

See the pictures below.

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The picture below is the FUG 16 ZY. Without a cabinet :). Maybe still a extra cabinet in future? I don’t know if I will look for it.

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FUG 10

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  1. German Fug 10 airforce radio installation

German Fug 10 airforce radio installation

 

The Fug 10 is a very complex installation for communication  between airoplane to airoplane (Bord zu Bord) and from airoplane to ground (Bord zu Boden). It consists of several receivers and transmitters for the shortwave and long wave and a lot of remote controlls. In other circumstances it is combined with navigation purposes. (Peil G6 with EZ6 receiver, then called Fug 10 P).

The transmitters are very stable in frequency, by using special temperature compensating arangements  in the oscillator circuit. Consider, that this oscillator is not crystal controlled. The heat inside the cabinet is very high, because the principle is a MOPA transmitter in a very small cabinet. The oscillator valve is RL12P35, which much deliver much driving power to the power amplifier. This power amplifier has to deliver about 60 watts to the antenna at CW mode, by use of 2 RL12P35’s.

This arrangement was not only the use of ceramic material, but also a special condenser block in the circuit of the oscillator. These condensers had a big dielectric loss with a particular temperature coefficient. More about this a extended explanation n the post EZ6 DIRECTION FINDER.

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Displayed in the picture above my Fug 10 equipment. It is in working condion! I use the the short wave transmitter and receiver in the 80 meters amateur  band and made several contacts. The frequence stability is amazing!

Most units (EK,EL,SK FBG3, SchK13 and U10E ) are in working condition. Upper row “Funkerschaltkasten (switchbox), EK receiver  (shortwave 3-6 Mc), EL receiver (long wave 300-600 Kc). Mid row “Fernbediengerat” FBG3 (tuning the antenne tuners, switching antennes etc.), SK (shortwave transmitter), SL (longwave transmitter). Lower row “Eigenverstandigung Verstarker” RG 10 (intercom amplifier etc.) , “Umformer” U10 e (rotating power transformer for the receivers).At the back of the rack are placed, not visible on the picture,  the AAG2 antenna tuner and the transmitter  rotary transformer U10S.

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Picture above: a close-up of the units.

On the left lower row, a important control unit, the FBG 3, explained later in the post. At the front 2 knobs for tuning the AAG for matching the antenna to the transmitters for long wave and short wave. One knob for long wave (blue) and the other for short wave (red) . This knob is mechanical attached to a synchro motor system. In the mid the antenna current meter. With the big switch, with scale, in the mid, you can switch the transmitters either for long wave are short wave and which antenna to be chosen. Normally one short  antenna f

or short wave, and a long antenna, the trailing antenna, for longwave. It is possible to change the long wave transmitter from trailing antenna to short antenna, so the short wave transmitter from the short one to the long one. This in case, one of the antennas is broken.

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In the above picture you can see at the left de ADb ‘s. In this case a ADb13 type. It is a remote connectionbox for the microphone-telephones in the oxygencaps of the crew. At the right the U-10-e rotarytransformer for the receivers.

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On this picture above,  you can see the trailing antenne  type AH-10. At the front of the “Funker Schalt Kasten” is a switch to move the antenna wire up or down. Also a indication meter is placed, for how far the trailing antenna is released.

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The FUG 10 with the fully working AAG 3. Note that the trailing antenna is also there, which came later in the collection.

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The AAG on the testbank. Just to be seen, the schematic diagram and wire connections.

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The inside of the AAG. Left the vacuum relay. When pushing down the CW key, the relay comes up. When releasing, it falls down again after a few seconds. This is working very well and pleasant. Above the long wave variometer. Above the variometer, the indication scale of the tuned frequency, the same scale is on the FBG3 control. Both he scales are turning synchron with tuning.

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Another view of the AAG. At the left, the short wave variometer to be seen. Just in the mid, the synchro -motor for driving the variometer coils. This motor is driving by a “Drehfeld  System” , a kind of electrical achs, coming from a same type of synchro in the FBG3. This synchro is turned by hand with a knob, with same scale as on the AAG, to tune the match.

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A nice look on the vacum relay. It can be activated (transmit and receive) by 2 coils, seen on the picture.

Till so far my FUG 10 installation. There are still some parts missing, maybe they come in future.

FuBl 2 panel.

FuBl 2

The FuBL2 setup, mostly used in the Ju88 heavy fighter plane, also in the Heinkel HE 111 bomber.

This FuBl 2 is a landing aid to the pilot, in landing securely on the landing stroke of an airfield.

Interested to mention is, that the receiver EBL 2/3 was  not only a common landing aid receiver, But the Germans developed another system with the aid of this blind landing system, using the EBL 2, for bombing targets in England, a automatic blind bombing aid sytem. That was in the early days the “Knickebeinverfahren”, working on 30 Mc.  A later version was the “X-Gerat”, which worked at a higher frequency of 60 Mc. So this makes this EBL2 receiver an historical receiver, because of the special use of it.

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The antenna system of the Knickebein transmitter. A complex system for small bundling of the radio beam.

Explaining this blind bombing system Knickebein in an easy way:

The principle is,  directing  a small bundled radiobeam, transmitted  by a very smal bundeling antenna system, just over the target to be bombed  The bomberplane just had to follow that beam, till he arrived  at the target. The pilot could follow that beam on a special instrument, called type AFN1, connected to the EBL2 receiver. This receiver, used in the early days of the development, was tuned then on the frequency of that radio beam Transmitter. The first trials consists of only 2 beams. See the picture below.

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Two beams were positioned just across the target. One transmitter in the north of Germany and one in Germany, close to th Dutch boarder.

That radio beam consists of 3 parts, eg one narrow beam an two lobs. One outer, a lob with a dotted  signal. In the mid, a constant signal ( equi-signal) , the other outer lob with dashes. The pilot only had to steer his airplane that way, he only heard the equi-signal in his headphones. If his airplane was to far away from the equi-signal, he heard either the dots or the dashes.

This beam was called the Lorenz beam. This beam was a standard common used signal, comming from a transmitter, just in line with the landing stroke at the end of it, for blind landing systems. By navigating  on a instrument, the pilot could make a save landing on the landing stroke at night time and foggy weather. This in case of blind landing on the landing stroke.

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The principle of the Lorenz beam.  The  3 typical beams. The mid dipole establish the main beam, equi-signal, the outer , switched reflector elements, did make the two lobs for the dots and dashes.

Below in the picture, the antenna system system.

X-Gerat:

A further improved version was the “X-Gerat”?  In the first trials, with Knickebein, with only 2 beams, the pilot flew along one of the beams on the equi-signal. Till he approached the the other beam. He heard then  first the dotted signal of the second beam, after a while its equi-signal. Now he heard only a mix of  equi-signals and released the bombs by hand on the target. He hoped, the bombs were on the target, it was not that secure.

X-Gerat was more secure. It used other receivers, see picture below. Also unfortuniatly not mine.

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It used more beams, see picture below. It used one leading beam, called Weser, just over the target, and three other, called Rhine, Oder and Elbe. The first leading beam (Weser) was in Germany. The other three at the coast of occupied France.

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These three beams crossing the leading first,  just before the target location, viewing from the position of the bomberplane. The crossing of those beams gave an indication of the position of the airplane.

First  look at the AFN1 instrument in the picture below.

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There are 2 needles on the scale of the instrument, a vertical one and a horizontal one.

The vertical needle of the instrument indicates the first leading beam (Weser), I mentioned. When the needle is just pointing to the dot, the plane is just moving into the right direction to the target. On the left side of the instrument scale,  there are 3 dots. The dots gave the position of the plane, when crossing one of  the 3 beams. The first dot (Rhine) is a position just close to the target. If the horizontal needle points to that dot, a lamp is lightning just above the centre of the scale. This is the moment, the first hand on the stopwatch is running. After crossing the second beam (Oder), the first hand is stopping, the second hand is starting to run. When after reaching the thirth beam (Elbe), the third hand is running, the second stops. After the third hand is reaching zero, they pushed down a knob on a that stopwatch  and afterwards the bombs are automatically released and went to the target.

This was a much more accurate system then the Knickebein system.

A nice told story, what realy was happening,  of counter attacks of the British for disturbing  Knickebein system , was:

They used diathermy apparates from Hospitals, which had about the same frequency of the Lorenz beam transmitter. They modified it to the same frequency, modulated it with the dots and dashes signals etc., and sended it  by a small beam in the direction of Germany, so simulating a false Lorenz beam. Mostly the German pilots picked up this false signal, and could not find the second one, thus missing the target.

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The “Knickebein Uhr” or “X-Uhr”. Unfortunatly not in my collection.

Bernhard/Berhardine navigation system.

Another use of the EBL 3 and EBL 2 receiver, normally used for  the FuBl 2 installation,  is also very interesting. It shows the very big knowledge of German engineers in developing all kind of navigation systems.

The EBL 3, type H or F, were used in another complex navigation system for the Luftwaffe to assist fighter planes for the  interception of enemy bombers.

The purpose of using this new system was that, the Knickebein, the X-Gerat and Y-Gerat systems could not used any more because of heavy interfering of British disturbing transmitters, described for instance above for the Knickebein system.

They wanted a system, which could not be disturbed, or at least very less.

This was called the “Bernhard/Bernhardine” system.

They started to build the systems in 1941 by Telefunken.

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Picture of a Bernhard beacon system, at Bredstedt in the far north of Germany, with its hugh antenna system of 28 m high. You can make an impression of it by comparing it with the persons at the front.

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Also north west of the Dutch village of Schoorl, at a high dune top at the north sea coast border, the remaining ring  of a Bernhard system. Here to be seen a circular part of the rail. Picture taken in 1980. The ring was broken down in the 1990’s however. But on internet, several remaining rings from France, Danmark, Germany, Poland etc. can be seen.

The system comprises a beacon station at ground level and a Hellschreiber printersystem in the aircraft. Bernhard was the FuSAn 724/725, the Bernhardine the FUG 120.

Why a hell printer system? Hell data is very difficult to disturb. You get only a good data on your Hell system, if the hell information data are just Hell data. If it is not precise, the system does not respond. So what you read on the paper is really true!

See picture 1 below the whole system.

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Picture 1.

At the right, of the picture you see the Bernhardine system, with the receivers EBl 3 and EBl 2. This complete system was placed in the aircraft. The main job of the system was to print the azimuth position on a special Hellschreiber printer. The receiver EBL 3 was a H (hand) or Remote (F) type. The F type had a separate channelbox controll. Different channels could be chosen, the last two were chosen for the Bernhard/Berhardine system. See also the picture of my FuBl 2.

Frequency range of the receivers and system was 30 – 33,1 Mhz. The both transmitters of the 724, did had a power of 500 watts. The power of the 725 was up to 5 KW. They nearly had  the same frequency, about 10 Khz difference,  so the signals could be heard easily on one receiver only. The dimensions of the Bernhard system was about 28 by 35 m. The diameter of the circular rail was 22 meter. The weight was about 120 tons.

At the left side of the picture, you see the Benhard system, a very big rotating antenna system, which was driven by two electrical motors on that circular rail of 22 m in diameter. At a speed of  two rev/minute. The Bernhard consists of two antenna sub systems, both dipole arrays.

One dipole array of the most lower part of the antenna, is transmitting continuously data in Hell format (identifier and momentary antenna azimuth, or a short text  message, coming from one transmitter. The center line of the beam is the azimuth position of the antenna, referring to the null, being the true north.

The second larger dipole array field, the most upper section of the antenna system has a twin beam radiation, coming from the other transmitter. The pattern has a small null between the 2 beams. This null is aligned with maximum of the single beam, this antenna sends a continuous AM modulated tone. This position and the dip, could also seen on a remote instrument, the AFN 1.

See figure 2 below, to see the different beams.

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Picture 2.

So the Bernhard is the transmitting part with 2 separate transmitters and the Bernhardine the receiving part, with the EBL3 receiver for the azimuth position and/or short messages. The EBL2 receiver for normal navigation.

The Hellschreiber printer in the aircraft prints two parallel tracks on a piece of paper. See picture 2 at the lower part above. The printer starts to run, when the first lob of the second beam strikes the aircraft, the second lob did stop the printer. The lowest picture in picture 2, is a real photograph of the printout.

The lower track of the two tracks, prints the azimuth value of the single beam , when the beam “strikes” the aircraft for a few seconds, eg. when the centre of the two beams is just pointing to the aircraft. In this case about 255 degrees. Null degrees was referred to true north. Which was remarkable. A station letter, also is printed (M) every 10 degrees.

The upper track prints the signal strength of the received continuous signal of the two beams. It shows a very sharp dip, at which point, the exact azimuth value is given.hell-HS120-LH-front

The dual trace Hell printer HS 120, on board of the aircraft.

The Bernhard/Bernhardine system was a medium range system. At a altidude of 4000 meters of the aircraft, the range was still about 350 km. At a altitude of 8000, it was about 400 km.

Note: Most of the pictures are from the website of Frank Dörenberg.

My FuBl 2 display.

This picture represent the normal blind landing system, used at airfields!

 

FuBl 2 panel.

Picture above: My setup of the FuBl 2.

On the left the EBL 3 F  receiver, a later version,  on the right above,  the EBL2 receiver. Just right below, the U 11, the power supply.  On the left below,  the AFN 1 indicator and the remote control of the EBL 3F, the FBG 2, for  a chosen frequency channel. There were 34 channels, the last two were used for the Bernhardine system.

As a FuBl 2 installation, the EBL 3 beacon receiver is working together with the EBL 2 marker beacon receiver. This is called the LFF , Landes Funk Feuer. In this  situation, the Ebl 3 receives an automatic gain control (AGC) signal of the EBL 2, and the EBl 2 receives the audio signal output of the EBl3.

When the EBl 3 is to work with the Bernhardine system, it is called then NFF, Navigation Funk Feuer, The FUG 120 takes over the place of the EBL 2. This is done by the SpKf 1a  mode switch (picture 1). This switch is re-configurate  the LFF to NFF  by the switch box UG 120. The EBl 3 gets its AGC input signal from the FUG 120, and the FuG 120 gets its AF output from the EBl 3.

inside the receiver EBl 2.

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                Added some new pictures of the inside of the EBL 2.  Beautiful                        construction.

The inside of the EBl 2 receiver.

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Above left.

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Above right.

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Behind the front cover.

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Below the chassis.

The EBL2 module from the inside. Watch that typical connectors. Also a lot a  valves for the HF stage of the receiver. The sensitivity of the receiver was increased comparing it with a normal receiver for blind landing. Note the typical connector, ” Kabelschwanze” called in German.

I managed to let the EBL 2 working. But the receiver part cannot exist without the the EBL 3. Also inside the EBL 2 some LF parts With a very selective audio filter.

Discription of the complete combination of EBL 2 and 3 will follow soon.

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EZ 6 direction finder receiver.

 Direction finder receiver EZ 6

“EMPFANGER ZIELFLUG”

Overall description of the receiver as a direction finder.

This is a receiver, part of the Geman “PEIL G 6″ aircraft installation called  “Peil Gerat 6″.

It was used for navigation/directionfinding purposes in large aircrafts like the Heinkel HE 111, Junker 88 and so on. It was common for EZ6, to be combined with the Fug 10, where it would have b

een placed instead of the E10L receiver. This was called the Fug10P (Peil).

There are 3  frequency bands: 150 -300 Kc, 300-600 Kc and 600- 1200 Kc.

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Photo above: front of the receiver

  • Upper left knob: A2 is AM, Eich is calibrating the frequency, A1 is BFO is used by navigating, Bandbreite is making the MF smaller.
  • Upper right knob: Entrubing is cleaning the signal from “humm etc.”
  • Middle knob: tuning the frequency.
  • Lower left knob: gain controll.
  • Lower right knob: arrow is navigating by a double needle instrument type AFN2. Circle is “Rund Empfang, frequency band 300 -600 Kc. Communication purpose as a replacement band for the E10L.
  • Lower middle: connection for headphones (left) and test entrance for test meter PV10 for measuring the internal voltages.
  • Small upper right panel: Behind the trim pot for calibrating the frequency scale.

The inside of the EZ 6 receiver.

Note the text on the pictures for removal of the various part blocks and connections.

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The front with cover panel removed.

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The block units from the receiver from behind.

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A connector of a unit.

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Here to be seen the contacts of band switch.

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Right the opened oscillator unit.

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Oscillator case with circuit removed.

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The removal of the oscillator ceramic plate. The green points are the data, where the wires, comming from behind the ceramiec plate, have to be desoldered.

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The three wave band coils of the oscillator. Above in the picture, the metal cover of the coils.

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The three coils explained.

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The connections of the coils, the grid, anode and coupling coils. Very handy for measuring the coils.

Temperature compensation for to stabilise the frequency of the oscillator circuit of the EZ 6.

All the components of it are mounted on a ceramic plate as a printed circuit, which was very revolutionair  in that time, nowadays very common. This has a very good effect at changing wiring capacities, due to warming up of them. Also mechanically very stable to heavy shocks.

Other provisions were these ceramic condensers in parallel , which have a temperature coefficient control. When they get warmed up by the air in the small cases of equipment, their capacity values changed that way, that frequency stability of the oscillator is improved.

These special condensers, you can see in the picture above, the green and brown condenser blocks.

On the printed circuit plate of the oscillator ceramic plate in the left side of the picture above, you see these green and brown  condenser blocks. All ceramic  condensers, in parallel, are placed over the the inductancies  in the circuitry.

About these condenser blocks, there was another type with ceramic ones with different specifications . Different from these of the temperature coefficient types.

It is so special, that I like to tell something about it.

One is a special, great type of ceramic condenser, which proof the great knowledge of German engineers in that time. Consider, it is now more then 70 years ago!

These were made by the German manufacturer Hescho, who patented it, and made also the ceramic coils holders and variometers.

The ceramic condensers are very special made. In fact, they are very bad condensers with a big dielecric loss with a particular temperature coeficient.

The principle:

Let us look at the internal capacities between the anode and grid and between kathode and grid, eg.  Cga and Cgk,  of a radio valve. When the radio valve is warming up, and getting warmer and warmer, when it is delivering power, the anode dissipation is increasing, these capacities are changing, the value is getting higher. So the frequency of the oscillator is changing and getting lower. Characteristic curves and values are well known for each type  radio valve.

Now we look at these special ceramic condensers. When HF energy is applied on these condensers, by the energy of the oscillator,  the dielectric electric losses of it changes by heating up of his body, so the value of capacity getting lower.  Hescho managed to measure that amount of dielectic loss in these capacitors. so they could produce a large variety of different losses factors  in the capacitors very accurate.

 That is just what we need to compensate the frequency change, established by the warming up of the valve , so the anode, by the increasing anode dissipation. This proces is acting much faster, then the influence  of the temperature compensating material, in circomstances that the valve is switched off, so cooling down, and later switched on again. Consider, that the remainig heat in the cabinet of this valve is still reaching the temperature compensation material, while the valve has been already switced  off for a while.

So they made the curve of  these combination of condensors that way, by putting several of these condensers in the circuit, that it is compensating the changing valve curve. So frequency stability, needed in such circumstances in the airplanes, was increased well , especially in these oscillators. Note that the German equipment, especially transmitters, were not crystal controlled by lack of crystal material, which had to come from abroad and was of course not delivered almost in that war time.

But these condensers were probably only made for oscillators, not crystal controlled, of transmitters.

You can see this arrangement in the various transmitters for navy, the LO40K39, the MOPA transmitters of the FUG 10, S10K and S10L. Even, I saw it in the oscillator part of transceiver FU Sprech- f of the army. But these were probably only condensors with a temperature coefficient. In these MOPA transmitters of the FUG 10, this stabilsation method is most effective. The heat is much in the transmitter cabinets. The oscillator stage, a RL12P35, had to deliver much driving power, so getting very warm, by his big anode dissipation, for driving the power amplifier of 2 RL12P35’s, to let this amplifier provide 60 watts on CW. Below a picture of the condenserblock in a S10K transmitter. In my working FUG 10, the frequence stability is amazing, while the transmitter cabinets are pretty warm. The oscillator is of course not crystal controlled!

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The condenser block of the S10K transmitter. At the right, a kind of printed circuit on the ceramic base.

I don’t think these condensers with that dielectrice loss were used in the EZ 6. Because it makes no sense. The oscillator in the EZ6 uses a low power valve, the RV12P2000. It delivers low energy to the mixer stage. So warming up of the anode is limited, so his internal capacities. But it might have been? I don’t know.

After the war, this manufacturing method of this special condensor was lost and forgetten. A synthisized module was used in oscillators. The frequency stability of them, depended on a crystal controlled reference oscillator. In fact a pity, but it worked well.

De EZ 6 as a direction finder.

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Here the EZ6 receiver  as my “Peil G6″ installation. Just at the right above a controllunit. With the switch you can do an automatic DF ,with the amplifier V6 just below the EZ6 and you can do a DF by hand, using the big knob on it by turning it to the left (L) or to the right (R). The DF antenna will turn to the left or right .Also the speed of the motor can be tuned. Right below the rotarytransformer U11 for the powersupply. In the middle the DF instrument type AFN2. Just all above  the motordrive for turning the DF antenna. Also seen the sense antenna. The complete system is a homemade version, except for the PRE 6 motordrive.

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The AFN 1 instrument. The vertical needle is pointing to the dot, when the airplane is at course. The horizontal needle is for the signal strenght of the beacon transmitter. Tuning at maximun signal of the receiver tuning.

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The DF antenna system. Above the sense antenna (homemade), below the PRE6 motor  drive unit.

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The PRE 6 motor and drive unit above and the ferriet antenne, just below the sense antenna, which is homemade one, by lack of the original one, but works very well.

This whole installation (certainly not original) is setup by my own and in fully working condition. The receiver is fed by the U11a by 24 volts DC. You can find the correct direction by rotating the little ferriet antenne  and watching the AFN 1.