Edgar wrote:
"---I don`t know exact antenna input impedance of it (the 1962 tube HF
receiver)."

The Radiotron Designer`s Handbook says on page 918:
"For use with domestic type receivers operating on the short wave band,
the standard dummy antenna is taken as being 400 ohms resistive, even
though the aerial reactance will not be zero across the tuning range, as
this gives an indication of average operating conditions."

Then on page 912 the book says:
"From the considerations detailed above, it can be seen that the coupled
circuit arrangement (an ordinary 2-winding antenna coil) of Fig. 23.2 is
generally satisfactory since it readily lends itself with minor
modifications, to applications using balanced or unbalanced aerial
systems."

Best regards, Richard Harrison, KB5WZI