One of our members (Who wishes to remain anonymous!) has found and been to one of the current broadcast sites of the buzzer:
The Buzzer source is fed to this shortwave site and other broadcasting locations using R-414S radio relay/phone lines directly from St. Petersburg's 60th Communication Hub (codename Vulkan, from a previous phone leak in February 2014, transcript) on Palace Square.
Mutiple VGDSh antennas and other arrays then take care of distributing the 4625 kHz signal to Western Military District troops (UVB-76/UZB-76/MDZhB is a collective callsign for all the recipients).
We know that the Buzzer can use multiple transmitters from at least 2 locations (second location has been found, Naro Fominsk, 55°25'35"N 36°42'33"E, 69th Communication Hub).
We also have a short video showing you the UVB-76/MDZhB reception directly at the site's front gate. The receiver used (Degen 1103) has its antenna closed on this video, so please ignore the signal scale, it's not accurate.
Antenna Diagram of the Transmission Site
Our friend Ary Boender described the antennas used in detail in his Numbers & Oddities #200, pages 5-8.
This was possible only thanks to one of our members! Thanks.