The photomultiplier tubes (PMT) based on microchannel plates (MCP) manufactured in Novosibirsk (Russia) are under investigation. These PMTs are used in KEDR, SND and CMD-3 detectors at the Budker Institute of Nuclear Physics.Principal problem of the MCP based phototubes is a photocathode aging due to ion feedback. For improvement of the photocathode lifetime the PMT with three MCPs has been developed. A procedure of the fast test of the photocathode aging has been developed. Using this test allowed us to improve the production technology and decrease the rate of the photocathode aging by about order of magnitude.In axial magnetic field of 1.5T gain of the triple MCP PMT decreases by about 3 times, photoelectron collection efficiency does not change. The time resolution for single photon of 35ps has been obtained.