Some features of the low-frequency cut-offs of synchrotron radio spectra ar
e investigated using numerical simulations. It is demonstrated that the int
erpretation of the radio spectra of compact sources must be based on an exa
ct (numerical) solution of the transfer equation. The need for creating VLB
I systems operating at meter wavelengths to study the physical conditions i
n galactic nuclei is justified. (C) 2001 MAIK "Nauka/Interperiodica".