[time-nuts] Function of cap to GND in isolation transformer circuit

Joop lous at xs4all.nl
Wed Jul 21 07:46:02 EDT 2010


I noticed in several circuits that the 10MHz isolation transformer in
input and output circuits have a 6.8nF or 10nF capacitor to GND. How
necessary is this for suppression of unwanted signals? Is the
transformer itself not sufficient? I would expect common mode issues to
be a bit worse with the cap in place.

The circuit I refer to can be seen here:

The first one is an output as described in the Efratom FRK manual, the
second one the input in the TADD-2 manual.



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