[time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived

Dave M dgminala at mediacombb.net
Sun Dec 14 15:58:49 EST 2014

The Pulse Engineering PE-68025 module from Electronic Goldmine 
(http://www.goldmine-elec-products.com/prodinfo.asp?number=G17078) has 
common mode chokes and LPFs on both Tx and Rx lines.  On clearance for $1.00 
each.  Datasheet is at 

Dave M

ed breya wrote:
> I investigated those 10b-t isolation modules a while back, and have
> saved every module from every network card and router/hub/switch that
> I have junked out. The very old 10b-t stuff is the best for getting
> LPFs and individual per-channel (port) type parts. When they started
> making 10/100 Mb/sec, the 17 MHz filters were eliminated, and the
> parts got integrated to ever-higher levels, with multiple channels in
> each module.
> You have to be able to find the data sheets to be sure of what's in
> them - some are transformers only, and some also have LPFs and
> common-mode chokes in various combinations. The filter sections can
> also be cascaded for even sharper cutoff, but there's quite a bit of
> crosstalk, so a lot of higher frequency stuff gets through,
> especially above 100 MHz, so it's mostly effective from around 20-100
> MHz. It has been mentioned before that very sharp filters will tend
> to have more phase noise (phase shift with temperature/component
> variations), but the negative effects depend on the application - I
> only care about frequency reference distribution to SAs and
> synthesizers, for example, so I don't worry about exact phase and
> timing between equipment.
> There is a nice variety of magnetic parts from all types of network
> devices, including DSL an ISDN.
> Ed

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