Ring or Crossover? Same circuit - different layout!
For those readers who might not be so familiar with mixers (or even circuits in general), but have seen mixers sometimes drawn as a ring of diodes, and sometimes having the transformer connections "crossed over, be assured that the "crossover" diode component is still just a diode ring folded up. Easy to appreciate, but very very important to layout and performance. Here, it is clarified for folk who have never untangled one.
These are "equivalent circuits". What shows as a transformer may be made in ways many and varied. In our case, the balun "transformers" are made from the coupled stripline structures. These two circuits show why I ended up having to stack two dual diode packs, one upside down, to contrive a crossover that would enable the ring circuit to be made with the layout I had. Give thanks too for what goes on in the tiny manufactured packs that contrive the crossover for us - apparently in fully symmetrical fashion, by internal 3D magic.
My first choice would have been a proper crossover quad pack, but the "distributors" belied their title function by expecting I purchase 400 minimum, also wanting full project details, expected investments in ordering, and a bundle of personal information that would have satisfied a internet identity scammer!
For lots more information on mixers - try Microwaves101 Mixer Page
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