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Year: 1960 ?? | Category: Broadcast Receiver - or past WW2 Tuner | ||||
Valves / Tubes | 6: UCC85 UCH81 UBF89 UABC80 UM80 UL84 | ||||
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Semiconductors (the count is only for transistors) | Tr.Gl.=Metal-rectif. | ||||
schematic requested |
Main principle | Superheterodyne (common); ZF/IF 468 kHz |
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Tuned circuits | 6 AM circuit(s) |
Wave bands | Broadcast, Long Wave and FM or UHF. |
Details | |
Power type and voltage | AC/DC-set / 220 Volt |
Loudspeaker | Permanent Magnet Dynamic (PDyn) Loudspeaker (moving coil) - elliptical / Ø 22 cm = 8.7 inch |
Power out | 2 W (unknown quality) |
from Radiomuseum.org | Model: Sekretär III 697/75GWU 3D - Stern-Radio Sonneberg, VEB, |
Material | Wooden case |
Shape | Tablemodel, with any shape - general. |
Dimensions (WHD) | 560 x 315 x 185 mm / 22 x 12.4 x 7.3 inch |
Notes | TA nur mit Trenntrafo möglich. |
Net weight (2.2 lb = 1 kg) | 7 kg / 15 lb 6.7 oz (15.419 lb) |
Source of data | - - Data from my own collection |
Model page created by Klemens Rhode. See "Data change" for further contributors.
All listed radios etc. from Stern-Radio Sonneberg, VEB, RFT; SONRA; -vorm.: EAK (Ostd.) - ex. AEG
Here you find 384 models, 308 with images and 280 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
Hits: 1366 Replies: 2
stern-sonn: 697/75GWU 3D; Sekretär III
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Timo Haveri
16.Jun.08 |
1
I'm restoring a Sekretär III 697/75GWU 3D radio. There wasn't a schematic for this model in RMorg but I used a schematic for model Sekretär III 697/62GWU which I believe to be close enough. There are no component values in the schematic and I need to know the value of one resistor. It is burned open and the markings are no longer visible. I think it is R11 in the schematic (in the lower left corner, antenna circuit). I have no idea how it got burned. There is no visible damage in the other components. Also I removed the 50 + 100 uF electrolytic capacitor can but I forgot to look which one is the first and which one is the second filter. I'm guessing that the 100 uF is the first. Am I right? The final question is about the half wave selenium rectifier. I measured its resistance with a digital ohm meter and I got 1.3 megaohms in the other direction and 1.6 megaohms in the other. I assume that it is bad? All answers will be greatly appreciated. Timo |
Martin Renz
17.Jun.08 |
2
Hello Timo, you can use the schematic of the 697/77 GWU Sekretär 4 modell. The component values are added there. You can't check a selenium rectifier with a digital ohm meter. Check the anode voltages instead. If they all are too low, or the rectifier gets hot, this indicates a possibly bad rectifier. For more information look here and may be here and here (about restauration in general by Hans Knoll) |
Timo Haveri
17.Jun.08 |
3
Thank you Martin. I have checked selenium bridge rectifiers before with a digital meter and they behaved just like normal diodes. None of them showed reverse leakage but this one does. I'll try carefully how the original rectifier performs. I already tried the radio with a silicon diode + resistor and it worked but quite weakly. It seems that the volume potentiometer has some problems. And it needs a new UM80 eye tube. Maybe some other tube is also bad. Timo |