Exhibits details page 4
After some considerations we have decided to create a new additional webpage, as the forelaying Exhibits details page 3 is becoming too much overloaded.
Created on 6 November 2011
State of affairs: 6 November 2011
On 7 October someone very kindly gave us a Fremess a
This wave meter type is, although completely different in concept comparable with a BC221.
This set is having 20 bands (30 kHz - 30 MHz).
In contrast to the BC221 this set is not relying on harmonics but is using direct signal generation.
The main difference between this set and the pre-war K126 Rö is that the latter housing is made of die-casting and later in the war they used steel plate material
Front panel of our Fremess a
Fremes.a, Serial number 6040, year 1943
As like a BC221, this set also needs a calibration book for all its 20 ranges. But, is using a fundamental signal generator in contrast to the BC221; where for higher ranges they employed signal harmonics, with all its ambiguity nuisance.
The valves are accessible when the apparatus rest at its back, which is also the regular way it should be employed
Looking from the bottom (housing being removed)
Viewing the right hand side of the set
The die-cast chassis is well visible we also can see that the chassis and front panel is a single piece of die-casting.
It is clear that the turret arrangement is constructed soundly, and is of typical Telefunken design
It is evident, that the design of a Fremess a goes back to the mid 1930s
However, it apparently full-filled military requirements. The individual who donated this set told me when he brought it to us, that it generated even at 30 MHz a stable signal (according the manual the accuracy is 2 ‰).
On 18 October we continued with:
the Lo40K39-d extra
Lo40K39d
This version was also used (maybe only for) reserve transmitter in U-Boote (submarines). In some respect its design differs from the regular Lo40K39..
It is also clear that the power supply is housed in the upper section and that the transmitter is mounted in the lower section. I think that this was done as to minimise temperature influence of the oscillator stage. As to increasing frequency stability.
We have to apologise that the type plates are a bit difficult to read
The main difference is that in contrast to regular sets, this type is having its connectors in the rear side and not on the right hand side
The main difference in the antenna tuning section is, that some of the matching pre-settings are being kept blank, thus these are not available. The matching condition onboard U-boats is having a more or less limited matching range. In universal operations the set must be able to tune between 3 and say 14 MHz for all sorts of antennae. Be it very short or relatively long ones
The rear side of our Lo40K39d
Please notice the connector at the bottom.
The inter-wiring of our Lo40K39d
Power supply of our Lo40K39d
A rear view of the Lo40K39d power supply
Please notice the mesh-contacts, which can only be found in the /d version.
Top view of our Lo40K39d power supply
Just between the transformer and the front panel on the right hand side - we see the mains loading capacitor, which should protect from "switching-on" power failures. A transformer is having before the core is being magnetised a rather low impedance hence, is consuming a high starting up current. I my perception, more designers should have done this. Who never encountered the phenomenon of blowing-out a fuse when a system is being switched on? It often is caused by choosing a too small transformer core.
On 3 November 2011 we continued with:
KST
The Körting version of the famous HRO receiver
KST receiver with its power-supply/loudspeaker
Like the original HRO frequency band (range) is changed by means of a coil-box
Our KST carries serial number 0306
Shown is Bereich 2 (range 2). Running from 11-22 MHz
Inside the top-lid is attached the explanations of the receiver controls
Extra informing: that the receiver is not to be connected onto the regular ground, though, only by means of the regular antenna; such as dipole or antenna counter poise
Top view inside the RX compartment
The tuning capacitor with its gear and tuning-dial was purchased from the US. Albeit imported indirectly via Portugal.
Filter-quartz at 468.0 kHz
Bottom view of the KST receiver
The black cable at the top left is interconnecting the RX and its power-supply/loudspeaker module
It is clear that some post war modification had been implemented. I obtained this set in the 1970s from Ebbe Pedersen. Whether he himself has done it I doubt.
The power connector is a substitute
Although, we have some years ago got the original one, we haven't had time to replace it
Viewing the interconnections
The two red rectifiers might have been adopted after the war, as its connection is coming from the original valve base
Viewing the bottom-side of the KST power supply
It all looks quite straight forward
On 6 November we continued with:
Morseübungsgerät
Controlling panel of the Morse trainings apparatus
Type Gl: S
Lieferer: Dr. Georg Seibt A.G.
Anforder Z. Ln 127001 (GAF stock number)
Bauart: Seibt (type after Seibt)
Hersteller: Seibt (actually manufactured by the Seibt Company)
Inside view of the Gl: S
Different perspective
The E 14 socket is meant for the neon lamp, which acts as switch-off device as to discharge a loaded capacitor at a given break-down-voltage
Schaltbild für Glimmlampensummer
I trust that with some fanatacy and knowledge of its principle, that one is able to understand the circuitry
Changing subject and regarding some items of our
Telephone related displays
10er Klappenschrank mit Wählerzusatz
10 lines field exchange unit with attached number dialing
This is a widely used device
Wählerzusatz
Attached telephone dialing module, as to act as an interface between field-telephone-systems and the regular telephone exchange system.
To be continued in due course
Finally our:
Berlin radar considerations
This Berlin related contribution does not entirely reflect what we actually possess, but is attached as it forms a subject of which we have some parts, like the Berlin PPI display unit SG224 and the pulse forming network LK1 (Laufzeitkette) and the pulse step up transformer.
After I presented my paper to the CAVMAG 2010 conference held on 19-20 April 2010 (The German Wartime Struggle to catch up with Allied Power Magnetron Technology), I discussed with Hans Jucker the properties of the pulse-forming-network type LK1. Which actually must have been a copy more or less of the same circuit found in the remains of the Rotterdam apparatus (H2S early version). He soon calculated the electrical energy stored in it. Its title is: Modulator of the German Berlin microwave radarset (equals GAF type: FuG224 or Berlin type A). I obtained these parts about 1980 from late Ebbe Peedersen of Denmark. Putting all facts together, I guess, that it remained from dismantling of a FuMO81 radar set which was captured by Danish authorities in 1945. Whether with or without British approval, I don't know. I obtained these components as it fitted to my future strategy. Although, I myself never could have foreseen that it ever was possible to swop the very rare Berlin radar PPI display unit (SG224). And showing it this way!
We very much would appreciate to find other Berlin radar modules or pieces
Pulse forming network type LK1
Please see for its circuitry Hans Jucker's paper
Berlin PPI display module type SG224
This module was obtained from Britain, some years ago
The following Berlin radar related photos, is not part of our collection, though being meant as to show how some modules look like
Berlin A type transmitter/receiver front-end
Feld II of the Berlin A system (serial number 391)
The upper module is like the previous photo, the lower section contains the modulator. In contrast to British H2S, it does not have the pulse forming HT section integrated as this was by German redesign an integral part of the transmitter section, which is from a technical point more appropriate, as the 10 kV pulse signal does not have to be fed by means of an external HT cable.
Feld I
Feld I (module 1)
The timing (waveform generator) section including the IF stage. This module is the top one left on the last photo
VK224
Control box of the Berlin radar system, its main function is to interconnect the system wiring incorporated in a single unit
Some time ago Horst Beck did send me the next photo
VK224, apparently the Naval version, Thus representing the same function as the previous module
This device was offered to Horst Beck some years ago though, he has rejected it (maybe too expensive?)
Berlin radar, mounted at a frame. Most likely of navy type (FuMO81 = FuG224) This type of mounting often was called: Prüftafel (Testing rack). I guess, it would have had then designation PT 224
Although, the text on top of the mains switching box indicates 230 V 50 Hz, this might have only controlled the voltage convertors for 80 V 500 Hz, like was used for H2S as well. Curious is, that the Germans, like in most other continental countries used 220 V 50Hz. Probably tailored here for British circumstances.
We would be very pleased to get any kind of feedback from those who have or can add additional information.
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Arthur O. Bauer
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