Please click your language flag. Bitte Sprachflagge klicken.

Ilmenau 675/55GWU

Ilmenau 675/55GWU; Stern-Radio (ID = 17438) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 365946) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 1371812) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 1371813) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 2338979) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 2338980) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 2338981) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 2338982) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 2338984) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 72613) Radio Ilmenau 675/55GWU; Stern-Radio (ID = 73348) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 72614) Radio Ilmenau 675/55GWU; Stern-Radio (ID = 73354) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 91418) Radio Ilmenau 675/55GWU; Stern-Radio (ID = 162687) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 166425) Radio Ilmenau 675/55GWU; Stern-Radio (ID = 200919) Radio
Ilmenau 675/55GWU; Stern-Radio (ID = 227107) Radio Ilmenau 675/55GWU; Stern-Radio (ID = 470805) Radio
Use red slider bar for more.
Ilmenau 675/55GWU; Stern-Radio (ID = 72613) Radio
Stern-Radio: Ilmenau 675/55GWU [Radio] ID = 72613 915x700
Select picture or schematic to display from thumbnails on the right and click for download.
For model Ilmenau 675/55GWU, Stern-Radio Sonneberg, VEB, RFT; SONRA; -vorm.: EAK (Ostd.) - ex. AEG
Country:  Germany
Manufacturer / Brand:  Stern-Radio Sonneberg, VEB, RFT; SONRA; -vorm.: EAK (Ostd.) - ex. AEG
Year: 1955/1956 Category: Broadcast Receiver - or past WW2 Tuner
Valves / Tubes 4: UC92 UCH81 UBF80 UEL51
Semiconductors (the count is only for transistors) Tr.Gl.=Metal-rectif.
Main principle Super-Heterodyne (Super in general); ZF/IF 473 kHz
Tuned circuits 6 AM circuit(s)     6 FM circuit(s)
Wave bands Broadcast, Long Wave and FM or UHF.
Power type and voltage AC/DC-set
Loudspeaker Permanent Magnet Dynamic (PDyn) Loudspeaker (moving coil) - elliptical
Power out 2 W (unknown quality)
from Model: Ilmenau 675/55GWU - Stern-Radio Sonneberg, VEB,
Material Bakelite case
Shape Tablemodel, with any shape - general.
Dimensions (WHD) 410 x 290 x 170 mm / 16.1 x 11.4 x 6.7 inch


  • Brückeneingangsschaltung
  • stetige Klangfarbenregelung
  • optische Bereichanzeige
  • Variometerabstimmung
Net weight (2.2 lb = 1 kg) 4.5 kg / 9 lb 14.6 oz (9.912 lb)
Price in first year of sale 269.00 DM
Collectors' prices  
External source of data E. Erb 3-907007-36-0
Source of data Radiokatalog Band 2, Ernst Erb
Mentioned in Historische Radios Band IV (156B)
Picture reference Das Gerät ist im Doppelband "Historische Radios" von Günther Abele abgebildet.

All listed radios etc. from Stern-Radio Sonneberg, VEB, RFT; SONRA; -vorm.: EAK (Ostd.) - ex. AEG
Here you find 379 models, 300 with images and 277 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.


Forum contributions about this model
Stern-Radio: Ilmenau 675/55GWU
Threads: 3 | Posts: 13
Hits: 460     Replies: 2
stern-sonn: 675/55 tuning probleme
Peter Hughes

Ich habe Probleme mit meiner Ilmenau 675/55 GWU.
Das Radio funktioniert, aber auf dem MW kommt mein lokaler Radiosender, der auf 1404 KHz sendet, auf der Tuning-Skala bei ungefähr 1200 KHz herein. Auch deshalb kann ich meinen anderen lokalen Sender nicht auf 549KHz einstellen. Das Radio wird nicht weit genug gehen.

Mit einem normalen konventionellen Radio würde ich den Oszillatortrimmer-Kondensator einstellen, um dies zu korrigieren, und dann die Niederfrequenz-Station mit 549 KHz mit dem Padder peaken. So wie es ist, erscheint der 549-Sender überhaupt nicht, da das Radio nicht so weit abstimmt.
Bei der 675/55, bei der die Permeabilitätseinstellung verwendet wird - bei der sich die Antennen- und Oszillatorblöcke in die Antennen- und Oszillatorspulen hinein- und herausbewegen - ist das Verfahren zur Behebung des Fehlers für mich nicht so klar.
Wenn ich mir die Schaltung anschaue, kann mir jemand sagen, welche Einstellung ich vornehmen muss, um die 1404 KHz-Station an den richtigen Ort zu bringen und mir auch die Einstellung der 549 KHz-Station zu ermöglichen.

Vielen Dank


I’m having some trouble with my Ilmenau 675/55 GWU.
The radio works but on the MW my local radio station broadcasting on 1404 KHz comes in on the tuning scale at around 1200KHz. Also therefore I cannot tune in my other local station on 549KHz.  The radio will not go down far enough.

With a regular conventional radio I would adjust the oscillator trimmer capacitor to correct this and then peak the low frequency 549 KHz station with the padder.  As it is, the 549 station does not appear at all as the radio will not tune down that far.
With the 675/55 which uses permeability tuning – with the aerial and oscillator slugs moving in and out of the aerial and oscillator coils – the procedure to fix the fault is not so clear to me.
From looking at the circuit, can someone tell me what adjustment I must make to  get the 1404 KHz station in the right place and also allow me to tune in the 549KHz station.

Many thanks,

Dietmar Rudolph

Peter, could you please copy your Geman text and insert it again via the 3rd icon in the editor tool bar after the icon "surcecode"? And afterwards purge your original German text.

In the moment your German text is already formattet, and so gives a much too broad post.

Best regards,


Peter Hughes

Hi Dietmar,


I think I've sorted that out now.

Thanks for the advice.



Hits: 1531     Replies: 0
stern-sonn: 675/55GWU; Ilmenau
Egon Strampe

Kein Empfang: Keine Spannung an 8 von UCH 81. Der große Rohrkondensator (300 pF) hatte Schluß.

Ton verzerrt, keine volle Lautstärke: Den 1,6 M unter der UEL 51 zur Probe mit Messgerät, Stellung 250 V, überbrücken. Wenn der Ton dann gut ist, ist es der 1,6 M.

Hits: 2550     Replies: 8
stern-sonn: 675/55GWU; Ilmenau
Georges Van Campenhout

Good morning, radio friends


I am currently restoring a 675/55GWU radio and I downloaded the circuit diagram and the parts list from

When I compare the 2 documents, it seems to me that the parts list (ID 93036) does NOT correspond with the reality. I think that this parts list belongs to another radio. Is it possible to obtain the correct one, please?


Than the technical part: The 675/55GWU has also provision to receive FM (UKW), but I do not understand the circuit diagram.

Where is the FM detection?

What kind of detection has been used?

What kind of FM front end is this?

Is the IF (673 kHz) the same for AM and for FM?

What about the IF bandwith for FM reception?


Can someone explain this to me please?







Arpad Roth † 27.3.17

Parts list is now deleted.
Wolfgang E. look for a suitable list.


Hans M. Knoll

Hello Mr. Campenhout.

Here a short description of the Functions for  this Radioset 1955/56.


Circuit Description from Hans M. Knoll Germany 02.2007


Stern Radio, Model „Sonneberg“


This AM/ FM- Radio is a cheap and simple  Circuit, I have never seen a lower quality.


The  RF Input has no Selectivity or amplification.

The Antenna goes through two IF- Traps (10,7Mhz) and a Balance- Transformer direct to the self –oscillate -additive -Mixer. His Output is formed from a 10,7 Mhz IF- Transformer (Bandfilter)    After the UCH81 follows a single -tuned -Circuit  (L20) with a coupling Coil L18.

After the UBF80 also follows a single -tuned  -Circuit (L22) with a coupling Coil L24.


The Demodulator is a single –Diode –Demodulator,  like in AM Radios used, called: “Flankengleichrichter” 


The first Units of lowprice Models on 1949/50 in W-Germany, use the same Technic in the IF-Part, not in the RF- Part.

Preselection with one Circuit was Standard.

Only Mixers with Multiplication (ECHxx) works some time like this, without preselection.

more here:korting_ukw_supereins_51w.html


The Demodulation do not works on Center of the Curve, she works on the left- or right- side of the Curve.  This Demodulator have no AM- Rejection.


The IF- Circuits are in Series upper side the AM lower side the FM Parts.

L 20 is shorted on AM -Reception.  The AM- Section is always in Function.


The Summ of  Band width  with the four IF- Circuits, must bee with, to prevent Distortion on the Modulation.  FM Deviation  +/ - 75 Kc must bee demodulated without  clipping.

regards Hans


Wolfgang Eckardt

Here is a block circuit for "Ilmenau 675/55GWU"

Wolfgang Eckardt

Georges Van Campenhout


Herr Knoll,

Thank you very much for your useful information.

I find this radio  very interesting, although it is - technically spoken - of a minor quality.

It does not work for the moment, but I wonder what the reception characteristics will be in a country like Belgium, with a large quantity of FM transmitters on such a limited area


Once finished, I will report of the result.


Warm regards




Hans M. Knoll

Hello Mr. Campenhout.

I will say: there was many of such quality Radios in the German Market

e. g. from my Company this one:


This is a TRF  2 Kreiser on AM, the FM Part is equal but preselection in Front of Mixer _ Stage

If you have any questions later, whe will see what whe can do.

Also,  best regards Hans M. Knoll 


Georges Van Campenhout

Good evening, dear radio friends,


I am slowly progressing the repair/restauration of this set.

Unfortunately some components are totally missing (someone tried to repair the radio before), and I have not the knowledge to calculate the values of the missing components.

Missing are:

  • A one watt resistor (R25, see circuit diagram please), in the return line from the output transformer to the second reservoir capacitor C53, which has been replaced (current value 47 µF)
  • A smoothing capacitor C38, between resistors R18 and R20. According to the circuit diagram it is not an elko.

Who can help me here in choosing the value for these 2 elements?

A further remark: most of the paper capacitors are leaky, and I will have to replace them.


Best regards










Hans M. Knoll

Hello Mr. Campenhout,

to start your restauration, place an 2 to 2,2 Kohm Resitor for  R20.

Later when the Radio operates,  and no one bring  a Partlist, i will help you to find the correct Value.
At moment only secure for Tubes is given and neccesary. The Voltage on C53 should have not more then 170 Volts, absolute limit: 200 Volts.. 

For C 38 you can use 0,22 to 0,47 uF. Greater Value ist recommendet. They reduce Hum on Audio.

With this values you can proceed.

regards Hans M. Knoll


Georges Van Campenhout

Guten Morgen, Herr Knoll,

In the meantime, I replaced all decoupling capacitors.

For R25 I used a 1200 Ohm 2 Watt resistor (I found this value in many other schematics of similar output stages)

For C38 I took a 0.22 µF one, as you suggested

After this the radio played, but with still a large amount of hum.

Then I replaced the elcos C45  (47 µF/450V) and C46 (100µF/40 V). C53 seems to be OK. The hum was better, but still there. Finally I changed the selenium rectifier by a modern Silicon one, and the radio works fine now!

Thank you again for your assistance

Warm radio regards from Belgium.




Stern-Radio: Ilmenau 675/55GWU
End of forum contributions about this model