|Tandberg Huldra 10|
Tandberg from the 70's are collectors items and since I actually worked one summer at Tandberg in the early 70's they bring back good memories for me. The latest generation of receivers (2nd version of Huldra 10, Huldra 11, and Huldra 12) had ceramic filters for the 10.7 MHz intermediate frequency for FM. It is also known that these filters deteriorate leading to reduced sensitivity over time.
SV8YM has pointed out that ceramic filters deteriorate due to DC on the terminals, especially the output terminal and that this leads to electromigration. In the Huldra 10, both filters have 7.1 V DC on the input. Filter F1 has 0 V DC on the output, while F2 has 2.1 V on the output.