Konstanz 8 Automatic

      Great forum! Tons of useful information regardless of whether one is restoring Saba radios or not. I have learned a lot from reading this forum (with the help of Google translate, my German being just enough to ask for a beer and be polite). Hope my English is not too difficult to follow.

      I am in the process of restoring this radio. This is not my first Saba, having restored a Meersburg 7 and Meersburg 6-3 (both automatics and the 6-3 included its remote control). Plus I have restored a bunch of other radios, including Telefunkens (Concertino 8 and 2194) and Grundigs (2066, 3028, 5040 3D).



      The radio arrived in good condition without the usual deep dirt and nicotine that usually accumulates after 50 years. I have no idea if it worked or not as I did not turn it on until after I had removed and replaced all the paper capacitors and bridge rectifier.



      Some one before me had worked on it as the dial strings for both AM and FM were completely wrong. I first corrected them, clean, greased, and oiled them for smooth and light operation. One problem remained, the FM dial would still slip. The clutch just did not have enough friction to drive the dial. This was solved by adding a small piece of kitchen paper towel (good thick stuff - like Bounty), cut to size into the FM side of the clutch. This dramatically increased the friction on the FM side and does not interfere with the AM side.



      After changing the capacitors and rectifier I applied power and it all worked, or nearly so. All bands worked, but the automatic just barely moved. The problem was the 0.4uF motor capacitor. After changing this the speed was fine. Automatic tuning on the FM band works great. On the AM side, however, the search function finds stations with exceptional signal strength. I happen to live within 1 km of a MW station antenna. Search finds this and only this station, no others. I have readjusted the motor drive transformer, but no help as it was nearly perfect already. I then tried various tube substutions, with a small improvement it radio performance, but no real help in the motor drive. Continuing, I realigned the IF transformers. This again, helped with performance, but no improvement with the AM automatic tuning. Note: on the AM bands, once a station is acquired, the motor drive is staying on the station. I can feel the motor drive trying to keep it on station if I try to move the tuning dial with my hand. It is just the sensitivity for finding a station is too high. When realigning the IF transformers, I noticed that the adjustment for the primary side of the 1st IF transformer had no effect on the pass band curve. I plan to remove that transformer and open it to see if there is a problem perhaps with the capacitor.

      I believe this radio has a delayed AGC, see circuit:



      Does anyone know what the nominal voltage of the AGC should be without any station tuned in? At what voltage will the AGC become active? If anyone can shed any light on how the circuit functions, it would be appreciated.

      Here are a couple of more photos:



      Well, here is the problem with the AM side. I am not surprised as the 30k resistor (R8) feeding the screen of the ECH81 had evidence of being over heated in the past and I replace it. Not sure where to go from here. I could put it back together, as is, and live with the poor performance. I could replace it if someone has a wreck that could be cannabilized.



      I have been following Achim with his restoration. I saw on page 11 that deltamike55 had a "bastler" that is a Konstanz 8 shown here. If that is available, I would be willing to purchase it (plus the voltage selector since mine is cracked).

      saba.magnetofon.de/showtopic.php?threadid=3664&pagenum=11

      Yes, Dieter, that is the one I need. Much appreciated.

      Voipman & Hans,
      Danke für den Link, um die Anzeige. Ich glaube aber, der Freiburger verwendet ein 10,7 MHz ZF-Frequenz, wo die Konstanz 6.75 MHz verwendet. Es würde schwierig sein, damit es funktioniert, unabhängig von den Kosten.

      Jeder, Antworten in deutscher Sprache sind willkommen. Google Translate macht die meiste Arbeit. Es ist nicht perfekt, aber ich bekomme die meisten dachten.

      Regards, Jim
      Any English speaking person looking for information to restore this radio, would do well review the information at this website:

      antiqueradios.com/gallery/d/10…e438f2fc3c2a7e54d4a45b7ee

      This is the Sams service information for the Saba Model 300-9C and 300-9T. It is not identical to the Konstanz 8, but it is very close. The main difference is the replacement of the EB91 with an EABC80 and the addition of the latching relay for the search function. But it includes far more service information than the Saba schematic, including coil resistances, more voltage and current data and very helpful alignment instructions.
      Fantastic, Dieter. I just need the rotary knob -- the portion that has the voltages printed on it. The one I have is okay, but at some time in the past, it was cracked.

      Do you still have the on-off switch? Last night I replaced the two 5 nF capacitors (see figure), with appropriate ratings, and discovered that one pole of the on-off switch is not working reliably. It may be difficult to remove that switch. I can live with the one I have. But if it is not too difficult to remove and you do have it, then I would be much obliged if you would send it too.

      Jim

      Perfect. That is exactly what the doctor ordered (hope that expression translates in German).

      The voltage selector is in better shape than mine. And yes, the on-off switch may be a bit tricky to change. But that is what the fun is all about. If it was easy, everyone would do it.

      I cannot express my gratitude enough. One old Konstanz 8 brought back to its former glory. My next step is the cabinet. I will have some questions for the forum on the best way forward. I do follow other restoration efforts in order to learn what works and what does not. I have my whole office following Achim's efforts (I manage a radar workshop) over on the other thread.

      Jim
      Wow Gruss, I think that with a little tender loving care (TLC), it could be brought back to life. ;)

      Seriously, it is nice to know that there is a source. Dieter has been kind enough to send what I to complete my restoration.

      I find technical level and the attention to detail of these old radios amazing. It was truly the beginning of HIFI sound. In their day, who could afford these radios? They must have cost a fortune in their time.

      Thanks, Jim