How many circuits / wie viele kreis?
What is the German method for counting circuits "kreis" in a radio? Do the circuits account for the number of complex conjugate pole pairs in the signal path, or resonant tank circuits involved in selectivity and image rejection? Is the local oscillator included in the circuit count?
This question was separated from another thread about the double reflex one tube superhet radio.
Counting of circuits "Kreise" in German radio receivers is not standardized.
- In most cases, all resonant tank circuits are counted: RF, IF, and oscillator.
- Sometimes also RF suppressor circuits are counted as well.
- Eventually, even resonant circuits within the stereo decoder were counted.
For the sake of advertising, big figures are always better than smaller ones! However, since ceramic filters became usual, no longer amounts of "Kreise" were told.
A similar problem was the counting of tubes in a receiver.
- To the mid of the 30ies only amplifying tubes were counted. Not conted were: Oscillator tube, rectifier tube, detector diodes.
- Later on all tubes were counted.
- Eventually, when combined tubes were usual, not only all tube systems, but even all tube functions (e.g. reflex systems) were counted.
Here also bigger figures were better for advertising. The same holds similarily for transistors and transistor functions. However, since integrated circuits and processors became dominant, those figures are irrelevant.
May I emphasize that only those resonant circuits are counted which are active simultaneously. If there are several bands, then not all circuits in a stage are counted, but only the active ones.
Easy to see in AM-FM IF stages, where usually two filters are combined, each employing 2 resonant circuits. For FM there are two circuits (10700 kHz) and for AM two circuits as well.
I would not consider wave traps, suppressors (e.g. for IF), tuning aids.
There is no strict rule, but for comparison we should try to give a realistic basis, and that is given by the number of circuits which contribute to selectivity (including the oscillator).
There seems to have been a DIN standard for counting of tube systems / tube functions, DIN 45312.
Since the counting has been done different in different times and/or countries we have a clear rule here - no matter what is stated otherwise. It is what Konrad wrote in post 3. We have this as strict rule!
But don't count on that since members can do mistakes. If you find such, please correct.