German FUG 10 aircraft installation.

German FUG 10 airforce radio installation

FUG 10 means: Funk Gerät 10.

The Fug 10 is a very complex radio communicationsystem 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.

Kl-details-Lorenz-C5-Block-1-2 (1)

This arrangement was not only the use of ceramic material, but also a special condenser block in the circuit of the oscillator. Just see the picture above.

These condensers had a big dielectric loss with a particular temperature coefficient. More about this a extended explanation in the post EZ6 DIRECTION FINDER.


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.

The picture below an older version of my FUG 10.


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.


In the above picture you can see at the left de ADb ‘s (Anschluss Dose ). 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.


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.

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


The vacuumrelay for the antenna.

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.


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.


Here the AAG on the testbank and wired up. To see if it is working. To the left the schematic of the manual. Lateron it is connected  to the FBG 3 at the FUG 10 display. And could be working from the FBG3 unit.


German Y-Peiler receiver SADIR R 87 E.

Some time ago, I bought a fine looking German receiver, the R87E SADIR.

It is a VHF directionfinder receiver, frequency covering 66 – 120 Mhz.

A picture is shown below.


The receiver was made in occupied France by for instance SADIR-Carpenter located in Paris.

It was used by the Luftwaffe as a direction finder in the Y-Peiler system. To find the location of the bomber plane groups, flying over Europe to the the german cities and industrial factory location to destroy them.

The code name was FuSan A81bb1 or Pulm SK. SK means short wave.

But to increase the frequency coverage in order to receive more ennemy frequencies, there were several  receivers with different frequency coverage. And different code names.

See a list in the picture below.

Y-Peiler Sadir

With the aid of other Y-Peiler stations, the could find the location of the squadrons, in order to intercept them  by delivering the info to the airfields centers with the  fighter planes.

The system was very effective.

An example, the use of my receiver, the type E:

In most allied bombers and fighterplanes, there was a transmitter receiver, the SCR 522, with TR 5053 of 10-150 Mhz, and the British type TR 1143, 120 – 150 Mhz. onboard for communication. The trx were crystal controlled. It had 4 channels in this range.

This trx also had a socalled “pip-sqeepe ” channel. Periodically , this channel transmiitted a short signal.  With the aid of the signal, directionfinder station on airfields in The UK, could determine the position of the bombergroups in that way. See also in the post             for explanation.

So the SADIR receiver, R87E, with frequency coverage 66-120 Mhz was very suiutable to receive this signal from especially the American bombers and fighters to locate them (TR 5053).

Below some pictures of the SADIR receiver as a Y-Peiler.

FuSAn_733_in. Sadir jpg

Picture above the SADIR receiver in the radio hut as a Y-Peiler.

FuSAn_733_box Sadir

Above the radiohut of the Y-peiler.


Picture above another Y-Peiler station.

In the picture below, a situation of the Y-Peiler system, called  Y- Stellung,  in German.


Below some pictures of the inside of my SADIR receiver. Because it was made in France, they used American radiotubes in it. The acorn tubes 954 and 955. Also the 6K7, 6L7 and 6Q7.

s-l1600 (7)

s-l1600 (6)

s-l1600 (1)

So this SADIR receiver is a very interesting VHF receiver. With a great history.

Aircraft receiver type EK3


The EK3 receiver,  the front panel.

Recently I purchased a new german receiver, the EK3. Which is pretty rare to purchase.

It is part of the aircraft installation, the FUG 10K3.

It was devoloped at the end of the war, about 1943. The matching transmitter is the S10K3.

It has a different frequency coverage. This to compare with the EK10 receiver of the FUG 10.

Frequency coverage is 6 – 18 Mhz.

It is suitable for mode A1 en A3.

It was used in conjunction with the normal used FUG 10 installation,  Also with a radiocompass Peil G6, a blind landing installation  FuBl 2 and with a seperate unit with the FUG 16. All these were mounted in the fuselage of a large aircraft, like Heinkel HE 111 or a Dornier.

The case was not there, but all was original inside, also the front was original. The case is a bit problem, because its dimensions are different from the case of a FUG 10/EK10 receiver.

Below some pictures of the receiver.


the backside.

$_85 (5)

the under view without cover plates.


A view of the other side.

Restauration receiver LO6K39.

Recently, I  perchased a  LO6K39 in very bad condition, uncomplete condition. It came with a seperate case, case frontcover and  a spare coildrum.

The receiver was bought by the former owner in de 1980’s and was “modified” by him. Like many surplus radio was done at that time.  A whole unit with LF-, a part of the detector- en CW filter stage  was removed. What a pity. Some mods are not always better.

Instead of it, some new hardware was added.  All this with integrated circuits etc.  There was no documentation with it. So a lot of work, finding it out, what it was and how it was functioning. But making a new circuit diagram, how it was functioning, was too much.

So I removed all the new hardware. And was finding out, where all the wiring was going to.

Also the frontcover was missing, so the voltmeter on the front. All original knobs were missing, so the mainswitch too.

But I decided to give it a try, to let it work again.

In the pictures below you can see the transmitter, when it came to me.

LO6K39 Ton B

The front without the cover. Watch the big square hole in it, where in normally the “on/off”switch and CW filter was placed, all removed.


The inserted new hardware with the PCB’s and integrated circuits.

First, I cleaned the chassis from all dirt etc. It was very dirty, it was in backstore more then 30 years.

The coil drum was not rotating at all. Much hardened grease between the geer wheels. I had to clean them, took a lot of time. In most german equipment that grease is fully hardened and have to be removed. New grease had to be added.

Next,  I had to add some missing parts of the detector stage and a new LF stage. The detector stage with a RV12P2000  tube and the coils were there already.

In series with the anode I added the missing  HF choke, and a LF choke to the high tension voltage and some decoupling condensors.  By lack of the original components, I used the primary side of a little AMROH LF output transformator and a little little ferriet  choke, suitable for the used frequency. The HF choke for preventing  HF energie to the LF stage and the LF transformer to get the LF info for the LF amplifier.

A new LF amplifier with a RV12P2000 tube. Just in style.The input conected by a 10 nF capacitor to the hot side of the LF choke.  The circuit is the same as seen in the circuitdiagram of the LO 6K39. Only no 2000 ohm secundary side, but a 8 ohm one.  Proving just enough gain forthe use of a headphone.

I made a new frontcover for the receiver. Also a new antenna post was made on the front.

Now I inspected the powersupply, which seemed to work well.

The mains power cable was connected directly on the entrance behind the receiver. Maybe I will put a switch on the cover. But I hope once to get another original unit. However hard to get.

I switced the receiver on now, but nothing was to be heard, no noise or signal.

After examing it all, there was no HT on the anode and screen connection on several tubes.

So I cleaned the contacts on the coil drum, I readjusted them for making good pressure contact on the drum and tried it again. I also inspected alle the coil units too.


The contacts of the coil units of the drum. The 5/VI K  on the coil unit means: 5-th frequency band,  coil stage 6( detector stage), K for “Kurzwellen” (shortwawe) Showing an L, it means a coilunit of a Long Wave receiver LO6L39. And not suitable for shortwave.


My spare coil drum. Above the revolver mechanics.

The receiver came alive at bit.

Now I noticed the detector stage did not oscillate in CW. It seemed to be something wrong with the resistance of the anode coil in the detector coil unit. I was lucky, because I had a spare one from a seperate spare coil drum (picture above). After replacing it, I saw it oscillating on my oscilloscoop instrument. But still no extra noise in the haedphones. It seemed that it was not on frequency.

For instance, when you tune the receiver in on 3600Kc, the detector must oscillate in CW also on 3600 Khz.

So I putted it on frequency. With the help of a frequency counter. Now a lot more of noise in CW.

I connected now a RF generator to the antenna post and setting it at 3600 Kc., with very low output of course.

I retuned al the HF stages of the receiver, by measuring the LF info at the LF output stage.

Now I heard various CW signals . Even SSB. The receiver was working again.

Only without a nescessary CW filter in it. The “Tonsieb”. It is in the missing unit.

But maybe in future I will add one?

It was a nice project doing it. It took a lot of time, but I was very satisfied about it.

The new frontcover , and the receiver in its case.


Side view receiver in its case


The new LF amplifier with the RV12P2000


Just right above the LF output transformer, Right below the RV12P2000 tube and left below the LF transformer as a LF choke.

Bendix aircraft transmitter TA 12.

The Bendix transmitter TA 12.

TA 12 front 2

This transmitter is originally an American made aircraft transmitter, but also used in the British Royal Airforce (RAF). Aircrafts like Mosquitos.

The  TA 12 has four frequency bands, one for longwave and 3 for shortwave. The funny thing is that each frequency band,  has it’s own VFO,  and only one poweramplifier for all of them, but again 4 output tuning filters with variometer inductance, to match it to the antenna. It delivers about 40 – 50 Watts on phone and CW. Modulation art, A-G2 modulation. In the mid the earial current meter.

The four knobs at the left are the channel preselector tunings, for each wave band one. Left of the knobs are the channel numbers you preselected. In the mid under you can see the knob for preselecting one of the four wave bands.

At the right are the four knobs for tuning, by variometer inductance,  the output filters for matching the transmitter to the antenna.

In the beginning, by lack of the original powersupply/modulator unit, type MT 28 BA , I used a separate modulator, homemade, with 2 valves 807 in the final.  With Ronette crystal microphone. It was doing very well. Also a homemade mains powersupply is used.

But some time ago, I managed to buy one on EBAY, a MT28BA. See the pictures below.

Bendix_MP-28BA (1)

Sideview with power connector.


Inside view with at the left the Audio PA amplifier valves, in the mid, the modulation transformer.


View components, at the right, the several fuses and the switch for switching from carbon mic to dynamic mic.

The unit had to be cleaned a bit and inspected.  But  nothing was wrong with it. The unit came also with home made cables and control box for working with the transmitter on AM, CW and MCW. For AM I used a T17 carbon microphone. Modulation deph 100 %. The noise level of the rotary transformer is not to heavy. It starts only at CW (contineously) and at AM (during transmitting).

Behind a small panel, you can chose by a switch, between a carbon mic or a dynamic mic. Note that at a type MT 28 B, this provision is not available.

Inside the transmitter.

TA 12 upper

The upper view of the transmitter.

The box at the right is the VFO compartment. At the left upper, one of the four variometer inductances, four each band one.

TA12 relay

View at the HF power amplifier with relay for switching the antenna and HT to the amplifier. The 2 tubes are in parallel.

TA 12 under

The under view of the transmitter. The motor for automatic channel switching at the left is missing. At the right, the VFO box again.

TA12 side

Side view with the four tubes of the seperate VFO parts. Each frequency band  has it’s own VFO part, so also it’s own tube. Left up the power input connector.

The modulator unit is doing very well. In mode AM, I can make almost 100 % modulation depth.  On CW, the tone is very stable. A pleasant way of working with it.

German directionfinder Peil G6.

Direction finder receiver EZ 6


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 been 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.


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.

 EZ-6 003a

The front with cover panel removed.

EZ6b 012a

The block units from the receiver from behind.

EZ-6 010a

A connector of a unit.

EZ6b 002

EZ6b 010

Here to be seen the contacts of band switch.

EZ-6 015

EZ-6 020a

EZa-6 001

To the right, the opened oscillator unit.

OSCb 001

Oscillator case with pcb circuit removed.

OSC 001a

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


OSC 004

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


The three coils explained.

OSC 001b

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

Temperature compensation 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 all a different 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!


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. But all these condensers, in parrallel, did have a different particular temperature coeficient.

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.


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.


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


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


Bordfunk 008

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.

Altimeter transmitter/receiver RT7-APN1.

 This altimeter is designed for measuring constantly the height of the aircraft above ground, terrain during flight. It is also suitable in conjunction with an Automatic Pilot System.

There are more principles of altitude measurements, but the APN-1

a  FM CW radar altimeter.

It is supplied with a double Range Indicator, type AYD 3. One for  till 400 ft and one for 4000 ft.  One ft is equal to 0,3048  meter.

So 400 ft is 122 m, 4000 ft is 1220 m.

Also a Limit Range switch is provided,

type SA 1, to switch for the desired altitude of the aircraft.

When no Automatic Pilot is used, the  Limit Range switch can be used in conjunction with a Limit Indicator, consisting of 3 lamps, red, white and green. All these items are at the dasboard. When not using the Automatic Pilot, a dummy connector is put in the receptable connector at the front of the transmitter/receiver J-106. When not placed and still Automatic Pilot is connected to this receptable by a cable, the change over switch on the Automatic Pilot box must be set on manual. When switched to automatic, these lamps have different functions.

In my installation that dummy is placed and the functions of the lamps are discribed just below.

At the Limit Range switch , the height of the aircraft , which is chosen to fly, or providing a flight with save height, can be chosen with the knob on it. When now the red lamp in the Limit indicator, is lightened, the aircraft is flying beneath the value on the Limit Range switch. When white, the height is about the desired value. When green, the height is above the value of the Limit range switch, so save height. See also the first picture below.

See below the block diagram of the APN-1 Altimeter.



Inter connection diagram picture.

The APN- 1 is a frequency modulated  CW Altimeter. It , just like another altimeter,  SCR 718, determines the time required for a radio wave to travel from aircraft to earth and return. A different method of time measurement is used , which depends on the observed difference in frequency between transmitted and received signal.


If frequency of a radio transmitter is changed rapidly at a constant rate (frequency modulation), the transmitter will change frequency in the time required for a radio wave emitted by it to travel to earth and return. The higher the aircraft, the longer the time required for a round trip and the greater the difference between the transmitter frequency and that of the reflected wave when it arrives at the aircraft. This frequency change is the proportional to the altitude of the aircraft.

If the rate at which the transmitter frequency carrier varies,  is known , e.g. FM modulation, and this  signal is also modulated at a rate of 120 cycles,  is CW modulation, his frequency is varied from his center frequency of 400 Mhz , between 420 and 460 Mhz at lower altitudes of a maximum range of 4000 ft,  the elapsed time corresponding to any observed frequency difference is then established. This frequency difference (elapsed time)  is converted, in an electronic  circuit, which delivers a proportional current to drive  a meter instrument, the Altitude Indicator.

The output of the transmitter is a FM modulated constant carrier of 0,1 watts, which is radiated from a small half wave dipole, located, often,  just under the wing of the aircraft. Each wing carries one dipole antenna, one for transmitting, one for receiving.

The principle of the altitude measurement in the APN-1 will be discribed in the following presentation  below.


Above the C is constant all the time, so  when T in increasing, H is increasing too.





Above: when T is increasing, rate of change carrier frequency  is stable,  the beat frequency is increasing.




Above means: FM modulation of 40 Mc, CW frequency , and  and velocity factor (300.000 km/sec) is stable, then the altitude is proportional to the beat frequency.



Above the principle block diagram of the APN-1.

Below some pictures of my APN-1 unit. Just click on the picture to get a larger one.


My  Altimeter unit RT7 APN-1.

Below the transmitter/receiver. Above left the Altitude Indicator and Range Switch unit. In the mid the 3 lamps  of the Limit Indicator. Just below at that, the 2 dipole antennas.


Transmitter/receiver box. Just watch the inserted dummy connector at the left, when the Automatic Pilot is not in use.


Left the height indicator with 2 scales on it. With the Range switch, switching between 40 ft and 400 ft. Below the 3 lamps of the Limit Indicator.


One of the small halve wave dipole antenna.

Comparison of FM and Pulsed Altimeters.

The APN 1 is a FM altimeter, a SCR 718 is a pulsed altimeter.

They are designed for different purposes. For instance for bomber aircraft, flying at great altitude and for fighter planes flying often at lower altitude. Fighter planes use often the FM units, while bomber planes use the pulsed altimeters.

The FM unit has a very small fixed error while the pulsed unit has negligible  percentage error. The FM unit is intended for better measurement  at low altitude, while the pulse unit is better at very high altitudes. Often you can see at pictures, taken in bombers, like B17 or B 29, the indicator unit of the SCR 718 , type I-152, is to be seen. See picture below.


Just right down to be seen the I-152 indicator at the Bombardier position in a B -29 aircraft.


Here to be seen in the background, the APN-1 transmitter/receiver, in a fighter plane.

In the week of the 28-th of march, 2018, I changed the instrument panel of the altimeter. I putted the antennas on a seperate base. With 2 m of coax cable to the receiver/transmitter. It all worked better, so the demo.

Below the pictures.


The new instrument panel.


The transmitter antenna at 400 Mc.


The receiver antenna.


The red lamp is lighten, that is correct, because the needle of the altimeter indicator is below the installed value of 50 ft at the limit switch.


 The back side of the panel. Note the rare connectors at the instruments.

The demo is going very well, if you move the receiving antenna. The indicator meter and the lamps are responding very quickly. This is correct, because at the functioning of the altimeter  at ground level  is always very unstable.  At bigger altitudes it is more stable.

Replica Würzberg radar transmitter, type SU 62 D.

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

Würzberg 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 Würzberg 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 rare 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.


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 Würzberg 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.


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

There are still some Würzberg’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, still existing Wurzberg in bad condition,  at Dwingeloo, the Netherlands at this moment, 8-10-2015, at the  former Planetron. Note, that the parabool reflector is not original, but copied after the war!

In the past, after the war, 2 Wurzberg Rieses were in use in Dwingeloo.


The 2 Würzberg’s beside the Dwingeloo radio telescope in 1950. All broken down at the moment.


                   The Würzberg at the right (eastern side).


Würzberg in use after the war at Kootwijk. For radio asteronomie.

After the war , most of the Würzberg 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.

They made the first map of our milky way.

To get more details in observations then those 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.  During some years after the new telescope was build, the left Würzberg ‘s were in use  for examinig the radiation of the sun. The Wurzberg in the  front moved in the 1980’ to the Wehr Museum in Munchen .The other also was already not there anymore. The Würzberg housing went to the Planetron, see picture.

Now back to Würzberg again:

Wurzberg foto

Wurzberg Riese, original picture.

LS 180

Transmitter valve,  type LS 180, in use in the radar transmitter of the Würzberg. The copper wires at the left are the heater connections for 5,8 -6,2 volt – 15 A.  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.

I looked funny to me to make myself a copy of the transmitter part, type SU 62 D. See the result in the pictures below. It is made at true scale.

transmitter 1

The front and above seen.In the mid if the picture the LS 180.

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. Left a power resistor(15 A) for putting the heater value at correct voltage, written on the glass of the tube.

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 the anode  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.

transm 3


The transmitter is working!!

But not really, only the heater is glowing.  An intensive 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.


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.


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 positioned around the LS180, so coupled to the anode,  by inductance.

WB-rep-Urechse-TX-separat HT cable 8 KV HT cable -2,1 KV a

The original transmitter SU 62 D , a picture taken by Arthur Bauer, PA0AOB, from his transmitter unit. Mr. Arthur Bauer has a complete and working  Würzberg installation in his museum.

The replica is now on display in my radio shack.

Radio compass receivers,

Radio compass receivers from Bendix.

This directonfinder receiver  MN 26 is in fully working condition. Also functioning as a communication receiver in cinjumction with the TA 12 transmitter, just seen a bit on the right of the picture.

A complete Bendix radio directionfinder installation

Here the MN 26 radiocompass and controll boxes.

On the picture the next items;

MT51-C remote control for the Transmitter TA12-B.

MR9 frequency control box for the RA 10 DB receiver.

MN28-LB control box for the MN 26 receiver.

Directionfinder loop antenna MN20-E.

DF Receiver R10-DB.

Transmitter T12-B.


The Ra 10 DB  DF receiver above, the MN 26 -E below in the picture.


The Azimuth controller , indicating the direction of the beacon transmitter, piled up by the compass receiver MN 26. The pile up is done by turning the controller by a bowdenkabel.

The compass receiver can be used  for communications, with a transmitter, type TA 12.



The direction finder SCR 269.


The remote control box of the SCR 269.


Aircraft receiver type RA1-B.

This receiver is a real old fashion general coverage receiver. Alle the wave bands are close after each other, when turning the wave band knob. When turning and  reaching the end of the last waveband, you start again with the beginning of the first.

It was used for communication purpose, but also for direction finding. It is a wartime receiver. But also used after the war by the dutch KLM.  It is a real nice, sensitive receiver, pretty stable in frequency at CW/SSB, only  a bit broad medium frequency stage of  1, 6 Mhz. But receiving SSB signal is pretty possible, if the band is not to busy with other stations.


 Bendix RA1-B.


This is the Remote Control box of the RA-1. Type MR-1B, in the condition I found it. The AVC on/off switch, the volume control is missing.



Bowden cables RA 1

Here the 2 original bowden cables for remote controlling the MR-1B.

When I obtained this remote control, together with a RA-1J, it  appeared to be a postwar (?) revision belonging to that  RA-J. The RA1-J was a revised postwar (?) one, because it had an extra mode swtitch on it’s front. Three positions: CW, VOICE and RANGE. This switch was also located at. the front of the  MR-1B. Watch also the missing switch : AVC on/off. The both potentiometers inside  were removed.

I decided to modify it into an original MR-1B, suitable for my original wartime receiver RA-1B.

Does anyone knows, which manufacturer it was, who carried out that revision?  Also what year, and in what aircraft is was being used.

I’m most grateful for more information. Pse let me know in the comment at the end of this post.



Finally the restaurated ware time MR-1B. When the function switch at the front of the receiver is set at “remote”, all the facillities are available on the MR1-B. Like band switching, frequency control, CW oscillator on/off, AVC on/off, audio and volume control.

At the right of the box, you can see the connector and cable to the remote entrance on the receiver.

RA1-B with powersupply

The RA1-B receiver at this moment,  with mains powersupply, by lack of the original rotary transformer , stowed away on a shelve, far away of it’s remote control. Watch the connector with cable at the right to the remote control MR-1B.

“Pip Squeak” American/British

American Contactor BC 608


Although a contactor is often explained as a kind of IFF device in several publications on internet, this is not true. A contactor, even if it is British or American, is actually a device for determining the position of an aircraft. It has nothing to do with identifying if an aircraft is a “friend” or “enemy”. (IFF).

This signal was also called “PIP-SQUEAK” signal.

It is a mechanical clock device with an electrical  contact, which switches on a communication transmitter for 14 seconds every minute at a special frequency channel. The direction finder stations home determine then by a cross sense the position of the aircraft.

This contactor is often used in the SCR 522 VHF transmitter/receiver.

The British types are used in fighterpanes, like spitfire, hurricane. A big part of the south-west coast of the British empire was divided in sectors. Each sector had his own airfields with fighterplanes. When a german attack was expected , radar (home chain) determined the location and direction of the ennemy planes. A certain sector was activated then. The fighterplanes of that sector went in the air to be lead to the ennemy. The direction finder stations of that sector (about 2 of them) could determine the position of their fighters by the “Pip-Squeak” signal caused by the contactor transmitter switch on. So by radio contact the could give eventually coarse corrections etc.


This picture above is a contactor, type BC 608: an American product. There have also been British types manufactured, for use in fighter planes.

  • The switch on the left is used to activate or deactive the so called PIP-SQUEAK signal.
  • The switch on the right is used to activate or deactivate the clockwork of the BC 608.
  • The knob in the middle is to rewind the clockwork.
  • The quarter section as seen in the upper right in the display represents the 14 seconds read-off timer.

British version PIP-SQUEAK.

The purpose is the same as that one mentioned before. It has been used a lot in the BATTLE of BRITAIN during WW2. The contactor was switching on the transmitter , at a special frequency being not a communication channel, during equal intervals for some seconds. So the monitoring control centres knew exactly the position of  the fighter planes by piling them up. If known, they directed the fighters to the locations of the ennemy bombers on their way to Britain,  by another radio channel. The locations of the ennemy bombers were detected by the HOME CHAIN radar stations along the coast line.

Pip squeak was an very effective way, leading the fighters to their targets.


Here the Brittisch version of the contactor, mentioned before. It’s a type no 4. Cover of the right box has been removed.

Left the remote contactor, which switches on the transmitter, often a TR9- D used in fighterplanes like the Spitfire.

At the right the maincontactor. It is a mechanical clock, which steps forward the internal remote contactor relay. Can be seen by moving of the needle on the front. In the mechanical clock assembly, there is  a heaterelement  installed for maximum stability. In the middle of it a key, for winding up the clock.

On the front of the remote contactor, there is that red part, which stands for 14 seconds. The whole scale is 1 minute. So the transmitter is switched on every 14 seconds of 1 minute.

I have tested it on a seperate transmitter, and it workes very well.

The remote contactor has been place on the right of the pilot seat, the master is placed behind the pilot seat.


On the picture above, the same. Only the cover has been replaced. This has to be done because of the temparature stabilisation internally, which was for my test not important..

Aerial Artificial type 1A

Aerial Artificial type 1A

The Aerial Artificial type 1A is used in the RAF for aligning the output transmitter stage of the pre-war T 1083 for test purposes. This type 1A is a prewar type.

A schematic diagram is shown is picture 1. Note the different conections for the different frequence ranges.

It can also be used very easily for aligning the TR 1196 or TR 9.

Aerial Artificial  1A

The front and the electrical diagram.


The front of my set.


Here you can see the Artificial Aerial, used by the Australian Army in testing the transmitters,

type T-1083.

The Artificial Aerial to be seen on the left on the shelve.


Transmitter/receiver TR 9-F


A short historie of the TR 9 and his successors.

The TR 9 is the pre war wellknown sender receiver.  Although the type 9 F is was used in the bigger aircrafts like the early Lancaster bomber etc. for communication between the airfieldtower and the aircraft or in close distance to others. The TR9 D is slightly different. It was fully remote controlled bij bowden cables. The TR 9 (D) were used in the Spitfire and Hurricane.

The TR9 F and D were especially used in the beginning of the war, in the battle of Brittain. Although his succesor, the TR 1133 was already there. The TR9 was in use in the Battle of Brittain instead, but not his succesor TR 1133, which supposed to be. The production of the TR 1133 was to small to deliver enough sets for the RAF at that time. They needed more transceivers for their increasing amount of fighters.

The TR 1133 was a VHF set with a frequency cover of 110 – 120 MHZ, and an output of about 5 watts, instead of that the TR 9 providing only 0,5 watts. The increasement of output was a big advantage.

The TR 1133 was already in use in the Spitfire and Hurricane at the withdrawal of the British army at Dunkirk in the beginning of the war. During the withdrawal the sets were all disadmantled out of the left behind airplanes, to avoid that they became in enemy hands.

But the TR9 stayed in service till after the battle of Brittain. Before the TR9 was superseeded after the battle by the TR 1133, the TR 1196 was introduced. The TR 1196 has a frequency range of 4,3 – 6,9 MHZ. The advantage of the receiver of the TR 1196, was that the receiver was crystalcontrolled.

After the TR 1196, came finally at the end of the war the TR 1133, a VHF set. But the TR 1133 was not so succesful and was soon replaced by the TR 1143.

Because there was a big cooperation between Brittain and the USA, they gave the design of it to the Americans. The designed the SCR 522 , with receiver the BC 24, and transmitter BC 625. It was almost the same design like the TR 1143. It was almost equal, even the typical british jones plug were used.

The SCR 522 was also used by the RAF in their fighterplanes.

Some technical details:

In the first early Lancasters, the TR9 F was positioned under the navigator table. And was used by the pilot for communication between airfield tower or between the squadron airplanes.

In the TR9D, the receiver type R1120 and the transmitter type T1119 is used, while in the TR9F the receiver type R 1139 and transmitter type T 1138. The receivers have the same schematic, but the transmitter has a different schematic. It is the internal connection I/C which is in the T 1138 is not connected, while in the T 1119 is. The I/C connector is an extra connection to input of the 3-stage audio amplifier in the receiver. In the T 1119 transmitter the I/C is connected to the external mic . So in the TR 9 D the 3-stage audioamplifier can be used also as an intercommunication amplifier.

In the T 1138 transmitter the external mic is connected to the micc transformer V3. This external mic connection can be connected externally to an A 1134 intercom amplifier acting as a preamplifier for an dynamic microphone. This for modulating the transmitter in mode A3 (anode/screen modulation).

My TR8 F It is working now in the 40 meter band with a crystal on 7078 Khz. It gives 2 mA on his antenna current meter into a Aerial Artificial no 1 A. ( See also the post Aerial Artificial no 1A). That supposed to be about 0,5 watts.

The receiver is a TRF receiver. It consists of two HF amplifiers, VRSG 18. Backfeed could be arranged in the second HF amplifier. This is arranged by a variabel condensor, which can be tuned on the front of theTR9. Called reaction.

A VR 21 is used as a triode detector. Followed by a three stage audioamplifier with also VR 21 triodes.

The transmitter is a three stage type and crystal controled.

One VT 20 as a crystal oscillator , A second one, VRSG 18 as a power amplifier. Also a a VRSG 18 as a modulation amplifier for A3 mode.

The transmitter has 2 channels. One is the normal channel N for communication and the S channel is the special frequency channel, which could be used for  PIPSQUEAK purposes. This system is discribed in the post PIPSQUEAK.

The front of the transmitter. 

Kerst 2008 065

Inside the transmitter.

Kerst 2008 064

The power amplifier tube in  the transmitter.

Kerst 2008 063

The power amplifier anode coil in  the transmitter.

The front of the TR9 F. Left the transmitterpart, right the receiverpart.

The intercom amplifier, type A 1368 connected, by lack of the original used amplifier type A 1134, to a homemade plugboard. My A 1134 is used for the T 1154 transmitter.

The front of the A 1368. Note the missing switch at the left , which is there at the A 1134. The amplifiers are the same, with same radio valves, same powersupply voltages 2 volt DC and 120 volt DC. Only the connector on the plugboard are smaller ones. So my plugboard can not be used with the A 1134.

Board with headphones connection, psu connection and the volume gain knob. The volume regulates the Second grid of the HF amplifier of the receiver.

This is a picture of a TR 9 in the Science museum. Probably the TR 9 D for fighterplanes, Spitfire, Hurricane. Watch the remotecontrole with bowden cables and in the mid the volume gain control. The remote control is extremely rare and hard to get.

The above pictures the setup of the TR9D in larger airplanes, like the Lancaster bombrer.

RAF Walter


WALTER  tr 3180.

Air-Sea Rescue homing transmitter beacon

This is a very compact beacon used by crashed aircraftcrew from a single seater dinghy boat on the water. It operated on the Air ship to Vessel (ASV) radar beacon frequency of 177 Mhz. It signal could be received by airborne ASV mk2 radar sets or Rebecca mk 3b equipment in Coastel Command aircraft. The TR 3180 was a selfcontained unit, comprising a battery of 90 volts in waterproof case. earialmast and a smalltransmitter.
The earial was a small dipole type.
The range of the beacon was about 50 miles, if the aircraft was flying on an altitude of 4000 ft. The battery has a lifetime of 20 hours.


The whole case with the complete beacon, including battery case and transmitter with dipole antenna.


The transmitter  with erected mast and dipole. Above the dipole and transmitter, below the battery case.


The battery case. The wires are supplying the voltage to the transmitter.


The dipole antenna on top of the mast. In the mid the transmitter.

TR 1196



four channels.

 Working condition.

This is a  transmitter-receiver used in multi seater airplanes like the early Lancaster etc. replacing the TR9 F in that place.

It was used for a short distance communication. The set was placed in a spitfire fighter just behind the pilot, just like the former TR9. In the Lancaster in the mid of the fuseleg.

It is a four channel transmitter. For the receiver, as well as the transmitter, four crystals are used.

The diffents units were: receiver type 25, transmitter type 22 and the rotary transformer powersupply type 104.

To handle the transceiver was much easier then the TR9, because of the 4 channels  in receiver and also transmitter.

Channel 1 was used for close distance to the airfield, channel 2 for  communication far away from the airfield at close distance, channel 3 was the Command Quard frequency and channel 4 for “Darky Frequency”. Just like in the TR9, the “Darky Frequency”was a frequency of 6,440 MHZ.

In England where it was overcast almost every afternoon and you are low on fuel, because you have been in the air 10 hours you called a “Darkie Station” which was a radio station on the ground (all over England) with a receiving radius of 10 miles. You would call, “Hello Darkie, Hello Darkie, this is Splashboard O Oboe, I need a heading to station 106.” Darkie had all the headings to every field from their particular station, and they would give you, “Splashboard O Oboe take a heading of 273 degrees for 7 minutes.” You then flew that heading and when at position, he let down his airplane through the overcast, and there was your field.

The radio set is remote controlled by a switch box for each channel a knob to push. On the picture a replica controll box is used. But the whole unit is working. Supply voltage is 12 volts, althoug also 24 volts systems exist. Which indicates that the 12 volt version is an earlier one.


Transmitter receiver TR 1196 a

Left the connection for the oxygenmask earphones and microphone. In the front the crystal types. At the right the replica remote control box, for choosing one of the four channels and controlling the transmitter.


Inside the unit.


At the right front the alternator power supply. Behind the receiver. To the right the transmitter.


In front a good view on the crystal board of the transmitter.


In front the earial- and ground connection and the type plate. Also the Air Ministry mark. The white earia is a modification chart.


Left the transmitter with HF earial coils, for each channel one coil. In the mid the four tuning knobs for pre tuning the HF stages of the receiver for each channel.


An overview of the chassis.


A side view.


A nice paper layout picture  inside of the housing. It showes the components layout of the transmitterpart for service.