I have at home two old USSR radios VEF 202. One is from a friend and the other one from a neighbour.
The first one works very fine on every band now and I replaced the contacts from the battery case too and the electrolityc capacitors.
The second works, but it makes a bad noise on the low part of the long waves a strong whistle and also the same whistle is appearing while receiving any station on medium waves. Also, the local station sounds distorted and sometimes even during the night the same problem happens to the other stations. When I tested the audio amplifier as an auxiliar, the sound is good. Where should I look for the problem?
P.S: At this radio I haven't replaced any capacitor yet.. but I don't know exactly if the cause of whistle is this.
Here is the diagram: