549 kHz According to this post, they now test with the 2 Megawatt TX, but with reduced power of 540 kW:
On the air – Bolshakovo. Kaliningrad region
Daytime reception
549 kHz, 540 kW
Two-megawatt transmitter lamps are warming up at reduced power
07/28/2023 15.00 Moscow time
https://vk.com/public158109176?w=wall-158109176_3332
Marco (2023-08-01)