Capacitor question on a Telefunken Operette Six

11/3/2010 2:06:31 PMRadio Joe

Trying to recap a really cool Telefunken Operette Six table top and came accross some oddly labeled caps. The caps are small and look foil wound. Reads as follows 100/20 and thats it. Looking for proper voltage and clear capacitance rating. I have the SAMS photofax sheets but no voltage given or M or P. Now I am fairly sure the caps are pico Farad due to there neighboring caps with same build and look but the voltage I have no clue on. there are like 4 for them like this labeling. 20/5, 220/30. Wish someone made a cap kit for this radio and then "paint by numbers". Anyone have a simular experience?

11/3/2010 10:05:58 PMThomas Dermody

Not sure of the code, but if clear with what looks like foil inside, these are metalized film capacitors, and do not need replacement. They are as reliable as today's metalized film caps.

T.

11/3/2010 11:23:47 PMEdd

Sir Radio Joe. . . . .

I concur on those caps probably being POLYESTER caps, and being used in the RF section and FM stages, and their capacitance values being in the picofarad range.

Also, they are almost right under a dipped silver mica cap in reliability and stability.

Appearance wise, most of the German jobbies were letting you clearly see the silver mylar foil thru the crystal clear casing.

Akin to:

(But probably NOT having that red end.)

The first numbers . . .100 . .20 . .220 pf would agee with the capaitances I am seeing on that units schematic.

the second numbering would not COMPLETELY agree with a tolerance nor a voltage rating across the board.

EG . . . a 30% tolerance ? . . . nor a 5V rating ? . . . come on now .

All you have to do is track both ends of a caps end connections against the schema and compare the schema against your part.

Then, from the aspect of needing to determine a caps voltage ratings, just clip DC digital metering across a cap and turn on the set to see the peak voltage initially experienced, since a Solid State Full Wave Bridge rectifier is providing instant power, then the warmed up tubes will start pulling its initially higher level down.

Choose voltage ratings according above that level.

HOWEVER
, I believe that those specific capacitor types are just
FINE
to leave as is.

73's de Edd

Trying to recap a really cool Telefunken Operette Six table top and came accross some oddly labeled caps. The caps are small and look foil wound. Reads as follows 100/20 and thats it. Looking for proper voltage and clear capacitance rating. I have the SAMS photofax sheets but no voltage given or M or P. Now I am fairly sure the caps are pico Farad due to there neighboring caps with same build and look but the voltage I have no clue on. there are like 4 for them like this labeling. 20/5, 220/30. Wish someone made a cap kit for this radio and then "paint by numbers". Anyone have a simular experience?
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