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Klopik is a nice radio constructed using the same idea like BITx - diode mixers and bidirectional amplifiers. They have similar levels of signal, so you can read about filters, tuning procedures eg. in many articles about BITx. Of course there is many differences, but in general they are similar radios - so it can help. Of course they have completly different construction of bandpass filters - we (in SP) call it "russian filters" or Drozdov filters - which can be built without hard-to-find components. They are tuning both - with trimmeres and changing spacing between coils.
It is of course extremely easier when You use any kind of SNA (eg PHSNA - poor hams scalar network analyser or other.)
I can not say more - I never saw english manual for Clopic.
good luck
MAc
sp9mrn