  A low-power stable tunnel diode oscillator with non-traditional single-layer
flat pick-up coil is an excellent MHz-range instrument with which one may study
weakly expressed peculiarities of the superconductive (SC) state in tiny
plate-like high-Tc superconductive (HTSC) materials. It enables to detect
changes about 1 pH of the HTSC film's magnetic inductance (changes about 1
Angstrom of the SC-magnetic penetration depth, lambda) with about 6 orders
relative resolution. Due to detecting coil's flat design, relatively low
operation frequency, so high relative resolution and an ability of this
technique to operate also in high magnetic fields the method has advantages
over others. They become crucial at non-destructive studies in thin flat HTSC
materials with small signals - especially near the normal-to-superconductive
(N/S) phase transition (at start of formation of electron-pairs). Just due to
such advantages a fine 'paramagnetic' peculiarity of the SC-transition was
detected by this method in YBaCuO film recently, which precedes well-known
Meissner expel. The method enabled to detect also a little absorption of a
power by the HTSC film upon its SC transition, with a peak located after the
onset of Meissner push-out - close to its center. Extracted from so complicated
fluctuation region these subtle effects (1-st is precursor, whereas the 2-nd -
posterior to the Meissner expel) indicate an existence of 3 distinctive
temperatures at N/S transition. Crucial role of these specific temperatures for
understanding of a real nature of the whole SC-phenomenon is discussed.
Possible relation between these temperatures and the 'singlet'/'triplet'
behavior of electron-pairs is pointed out and argued.
