[time-nuts] Terminators on empty outputs/connectors

Graham / KE9H ke9h.graham at gmail.com
Fri May 25 11:33:28 EDT 2018


As usual, the answer is "it depends."

If the output is a single isolated output, then terminating load not
required, but no harm providing.

If the output is a multiple output, from a single driver, through a
resistive or transformer splitter, then the level stability on all ports
and the port to port isolation is dependent on the proper termination of
all ports.
So, if multiple 10 MHz or 1 pps outputs, terminations highly recommended.

--- Graham

==

On Fri, May 25, 2018 at 10:21 AM, Dana Whitlow <k8yumdoober at gmail.com>
wrote:

> I recommend putting terminators on unused ports, on general principles.
> But I don't
> think it would ordinarily be necessary to use big-bucks terms, unless the
> distro amp is
> really cheaply made.
>
> If you have access to a VNA, it would be interesting to measure the complex
> transmission
> coefficient from input to one of the output ports while experimenting with
> variations of
> the number and locations of terminations for the other output ports.  If
> you find that none
> of such manipulations have any visible effect, then you can probably skip
> using terms
> on unused ports.  I should mention that any such measurements should best
> be performed
> at roughly the intended operating RF power level.
>
> And for extra credit, report your findings to this discussion group.
>
> Dana
>
>
> On Thu, May 24, 2018 at 3:41 AM, Clay Autery <cautery at montac.com> wrote:
>
> > Putting in a hardware order...
> >
> > Question:  Is it recommended to put terminators on all unused GPS Distro
> > amp ports?  Output ports on GPSDO and NTP servers (10MHz and PPS).
> >
> > Thanks!
> >
> > --
> > ______________________
> > Clay Autery
> > MONTAC Enterprises
> > (318) 518-1389
> >
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