Hi everyone
I'm new on this forum and I arrived after learning of the wonders of SABA tube radios.
I do not want to complicate my life too much and I decided to get involved Radio SABA of ‘60 years whose tubes can still be found without problems.
I bought on Ebay some radios, namely:
1) SABA Freudenstadt 125 Stereo
2) SABA Villingen 12 (chassis only)
3) SABA Konstanz 18 Stereo
4) SABA Villingen 11 North.
These radios are still working and I have already modified the power stage with semiconductor diode insertion and resistor of adaptation.
I replaced most of the paper/electrolytic capacitors placed at critical points and I checked them; in fact have worrying features.
For example (SABA Freudenstadt 125 Stereo) capacitors on the secondary of the HV power transformer of 4.7 nF 1kVdc (C78 and C 79) now have the capacity of 6 nF with tgd 0.085.
The capacitors in series loudspeakers tweeters of 10 uF are now 16.3 uF with tgd 0.33.
In any case, my questions, for now, are the following.
The radio SABA Villingen 11 North did not work FM reception.
In the tuner I replaced C110 and C111 and slightly retuned the O.L.
Now works but there is a frequency drift down for the first 10 minutes of operation, for about 100 KHz.
I would like to know the temperature coefficients of the capacitors in question and whether there are other possible causes of drift (tube ECC85 was already replaced ).
Furthermore, why the radio SABA Freudenstadt 125 Stereo front loudspeakers are not equal to one another (see also exemplary photographed in Radiomuseum).
Best regards
Gianpaolo
P. S. I’m very surprised that, with a few tubes and more 50 years ago, SABA engineers were able to achieve equipments very efficient in reception and sound reproduction.
I'm new on this forum and I arrived after learning of the wonders of SABA tube radios.
I do not want to complicate my life too much and I decided to get involved Radio SABA of ‘60 years whose tubes can still be found without problems.
I bought on Ebay some radios, namely:
1) SABA Freudenstadt 125 Stereo
2) SABA Villingen 12 (chassis only)
3) SABA Konstanz 18 Stereo
4) SABA Villingen 11 North.
These radios are still working and I have already modified the power stage with semiconductor diode insertion and resistor of adaptation.
I replaced most of the paper/electrolytic capacitors placed at critical points and I checked them; in fact have worrying features.
For example (SABA Freudenstadt 125 Stereo) capacitors on the secondary of the HV power transformer of 4.7 nF 1kVdc (C78 and C 79) now have the capacity of 6 nF with tgd 0.085.
The capacitors in series loudspeakers tweeters of 10 uF are now 16.3 uF with tgd 0.33.
In any case, my questions, for now, are the following.
The radio SABA Villingen 11 North did not work FM reception.
In the tuner I replaced C110 and C111 and slightly retuned the O.L.
Now works but there is a frequency drift down for the first 10 minutes of operation, for about 100 KHz.
I would like to know the temperature coefficients of the capacitors in question and whether there are other possible causes of drift (tube ECC85 was already replaced ).
Furthermore, why the radio SABA Freudenstadt 125 Stereo front loudspeakers are not equal to one another (see also exemplary photographed in Radiomuseum).
Best regards
Gianpaolo
P. S. I’m very surprised that, with a few tubes and more 50 years ago, SABA engineers were able to achieve equipments very efficient in reception and sound reproduction.