Dampfradioforum

I have a Saba Bodensee Automatic 3DS which I have replaced all electrolytic and paper capacitors. I am wondering if there are any capacitors around the tuning motor which should have different values for 60 HZ operation. This radio was brought from Germany by an immigrant to Canada. The motor seems to run OK with the capacitor values on the schematic but I have read about other Saba Automatic radios being modified for 60hz. I have drawn arrows on the schematic to two capacitors which may be candidates for modification. If anyone has done this please let me know if these or any other capacitor values need to be changed. Any advice is welcome

Hi,

if nobody shows up who did this - another solution may be to check radiomuseum.org for (may be later) automatic models and compare the german with the export version.

Regards
Oliver

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Thanks Oliver. I have looked at Radio Museum for discussions about the motor capacitors. They discuss the caps for the later generation automatics. The circuits look different so I am not sure I can apply the same solution to the Bodensee.

I did find a reference to the motor capacitors in a Saba forum. For 60hz operation in Canada, the two capacitors I pointed to in the schematic are reduced to .35uf and ,2uf .

Hello, John,

the 0µ5 capacitor is tuned to 50Hz together with the motor inductance and forms the external resistance of the motor end pentode. This way the inductance of the motor can be calculated: L=1/(2pi*f)^2*C --> 1/(2pi*50Hz)^2*0µ5=20,3H. This gives a capacitor of C= 1/(2pi*60)^2*20,3H = 0µ3466 -->0µ35 or 0µ33 at 60Hz

With the phase shifter capacitor you should aim for the same current as at 50Hz - only I don't have that available at the moment. But the 0µ2 you found should be ok.

Translated with http://www.DeepL.com/Translator (free version)

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...und glüht auch die Anode rot, ist die Röhre noch nicht tot.

Mit freundlichen Grüßen, Peter R.

Thank you Peter. I installed the new values ( .2uf and .33uf) and the motor works perfect.