[time-nuts] Noise and non-linear behaviour of ferrite transformers

Stefan Heinzmann stefan_heinzmann at gmx.de
Fri Jul 25 07:31:25 EDT 2014

On 24.07.2014 18:00, Ackermann, John R wrote:
> Just FWIW, the TADD-1 uses transformers to provide DC isolation, but the
> shield side of the coax goes to ground through a 0.1uF cap.  The hope is
> that this reduces the issue that John's referring to (and which I've
> seen plenty of times using baluns).

For optimum results with respect to high RF frequencies, I'd expect that 
you would need this cap to be annular, so that the cable can pass 
through the middle, and the outside connects to the chassis hole all 
around. This is like a feedthrough capacitor, except that the wire that 
goes through the center actually is a coaxial cable.

While feedthrough caps for single wires are common, I haven't seen any 
for coaxial cables (rigid or semi-rigid cables come to mind). Do they 
really not exist, and if so why? Or have I failed to look in the right 


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