[morzh]

Well, Yesterday the cap came, I soldered it in.
Today checked all tubes, then checked the AC voltages, then DC voltages.

Then put the scope to the output.
The stability of this thing is very good, as promised in Master Degree thesis of Bill Hewlett's.

Here are some photos:
Notice the stability of the amplitude over the frequency range:
(Freq. reading could be seen on the scope at the bottom)
Front view
   
10 Hz
   
100 Hz
   
1kHz
   
10kHz