posted on Jun, 5 2010 @ 10:38 PM
My first thought is they can no longer buy the vacuum based, power tubes needed for the transmitter. Russia was big on vacuum tube electronics well
after everyone else went to solid state circuits.
If you happen to be listening to 4625 and hear people talking in muffled tones, followed by a noise that could sound like a flute; it's called
SELCAL. It's used in aviation for airplane stuff.
One thing to consider other than my first thought. Maybe Russia has decided to drop this frequency. The AM carrier used is a spectrum hog with this
band. Other parts of the world use the radio spectrum and this signal may have interfered with them.
I have several radio frequency source books, Klingenfuss for the radio inclined, that shows this frequency being shared as an unidentified digital
data station (2010 reference) broadcasting SELCAL , and also CXF-2 out of Montevideo Uruguay as a (meteo) weather station.
BTW: I just have static on that frequency. In looking over my logs, I have never logged that station as anything unusual. This isn't unusual in
itself, as I have confirmed contacts as far east as Hamburg Germany. Just can't seem to get more central and Eastern Europe. I can also go west to
Australia and through China, Korea, Japan, and far eastern Russia.