Hi fenris and palmar,
interesting to follow your theories, but it’s “theories” finally “as long as it works”, which it obiously does.
I was more concerned about the “naked” (unprotected) F1 SAW device (galvanically coupled to the antenna input by a stripline matching stub), which, as a highly sensitive device, literally must be “scared to death” in the attendance of ESD tensions.
At least I might now understand AirNavs frequently recommendation for a “DC Block”, that I expected to be part of the frontend design of course, and to be realized by a “capacitor” as mentioned by palmar. Though not a good insurance against ESD harm, it appears to be even “ better than nothing”. And, as an “integral part” it would almost have cost “a nothing”, as compared to an external (commercial) device, whose specifications have to be paid for, though not needed in this type of “application”. It simply serves for measurement purposes in higher qualified applications, as discussed before.
I agree with palmar, that AirNav have considered the above regarding their later batches of RBs. They say so themselve.
Future will show, if the preventive measures, that obviously have been taken, will result in a lower yield of receivers to fail.
I personally would prefer “helical filter arrays” in a receivers frontend as their design is of a “mechanical” rather than “solid state” nature, the latter beeing highly sensitive to ESD as mentioned many times on the occasion of preceeding postings, if not by the manufacturers of those SAW devices themselve. SAWs obiously are a cheaper solution.
Karl
