[Premium-Rx] E311 mods and operations

[F3WT]

Hello,

Let me thank you very Michael (G8MOB) and Eugene ( W2HX) for their answers I appreciated a lot.
I understand the difficulties  in modifying as the system is very compact. But I found the documentation very much extensive 
up to including layout,topology and soldered components drawings.On a webpage, funs describe  exchanges of various a-drifted capacitances 
and other ( probably minor ) repairs. One guy  reported even wobbling properly the SSB filter to better its uneven frequency response.
This is for systems prior to version E, as version F - and last of its  series - got its first mechanical filter on the 370kHz stage.
What I like is its down-conversion,which made its come back in modern designs ( if not SDR or all digital)  one of the last rig as such  launched recently being with the TS590 of Kenwood.
What I 'm concerned with  is with its selectivity stages far down the signal path. 
Collins engineers for the R390 thought very much in these circumstances which mixer tubes (and I think there as many as in E311!) provided best intermodulation resistance and signal path linearity. They came up no wonder with a triode and chose by experimentation the 6C4. Made me think why not swap the two halves of each  ECH81 concerned... 
That's why I thought previously  about those 7360s  and which were used by Squires & Sanders receivers because of that.
But I understand from your comments, Siemens at that time did nevertheless an outstanding job.
As I have a PMSDR, ready to be connected to ZF-output,( 30 kHz)  a convenience very south after - to link old with modern, and may be become better eligible for discussion on this forum! hi!  - it might be 
interesting to use its panoramic displays for re-alignement, if necessary. Or just watching what is going on on the band (by looking through the system rather than direct  provided sufficient bandwidth is set). 

Well, thank you again and I wish nice operations with those oldies but premium in performance I reckon.

Pierre.
F3WT.