I just got new photos from Serbia.
The station is Radio YU1 (="Ju jedan") from Belgrade area.
I think this is the biggest pirate in Serbia with about 5 kW of power. Here you can see the self-built transmitter with huge tubes. I hope I will get more detailed information of the tubes later.
Click photos (taken by Texas) for bigger views >
I have heard this station a few times here in Finland around 1700 kHz with huge signal. I visited Serbia in May 2008 but I had no connection this station.
Here is one old audio-clip of YU1 from my archives! I heard this on 26.2.2005 on 1667 kHz.