[time-nuts] Simple GPSDO Multiple Outputs - buffered line driver options?

[Dana Whitlow]

Re cross talk, I'd suggest:

Fairly equal levels on all the used outputs, to minimize the effects of
crosstalk between them.  This is especially important if you're using
RG-58 or similar cable, which leaks like a sieve.  Crosstalk of this
sort will tend to screw up the edges of a PPS pulse, possibly in a way
as to lead to unreliable/unstable triggering of some of your devices.

As high a level as your devices will safely tolerate, unless you're
concerned
about leakage into other systems, like kb8tq's WWV receiver.  Again, I
suggest
avoiding RG-58 and similar single-braid-shielded cables.  This has been a
significant problem for me, receiving WWV at 10 MHz.  I've been able to
some-
what mitigate this with big clamp-on ferrite chokes, but I still have some
issues.

Dana    K8YUM

On Tue, Jan 21, 2020 at 9:28 AM Taka Kamiya via time-nuts <
time-nuts at lists.febo.com> wrote:

> I've tried daisy chaining 4 HP5335A.  By the time signal got to the 4th
> box, it was too weak to reliably drive the 1 pps.  I had a terminator at
> the last tee with short length of RG58s between boxes.  I guess some box
> puts relatively heavy load on the signal?
>
> I'd like to know why 10V is a bad idea.  (besides too close to the upper
> limit)  Cross talk between what/where?
>
> To OP:I have video amplifiers Extron MDA-3V successfully used for this.  1
> port in, 3 ports out ones by Extron are very inexpensive at 10 dollars+/-.
> I never did formal testing but reading on all counters matched exactly.
> They are 75 ohms but it didn't matter in my use case.  You can
> change/adjust internal resisters if you are concerned.
>
> ---------------------------------------
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
>
>
>     On Tuesday, January 21, 2020, 7:45:22 AM EST, Bob kb8tq <kb8tq at n1k.org>
> wrote:
>
>  Hi
>
> What are you driving?
>
> Most “normal” gear is pretty happy with a fairly wide range of input
> levels. Obviously things
> like termination and long lengths of coax can get into the act. For 4
> outputs, a passive splitter
> with 6 db of loss should do just fine. You have only taken the output
> voltage down by 2:1 ….
>
> Just for reference:
>
> https://www.avionteq.com/Document/53131A-specification-sheet.pdf <
> https://www.avionteq.com/Document/53131A-specification-sheet.pdf>
>
> Calls out a 200 mv to 10V RMS input level as acceptable For a variety of
> reasons, 10V RMS
> is a really bad idea (cross talk ….). Lower is better in this case.
>
> Bob
>
> > On Jan 21, 2020, at 4:19 AM, skipp isaham via time-nuts <
> time-nuts at lists.febo.com> wrote:
> >
> > Hello once again to the Group,
> >
> > May I ask what the current relatively simple options are for
> > expanding a Thunderbolt or equivalent... output for distribution
> > to multiple devices?
> >
> > Although I expect only two or three isolated / buffered outputs
> > will be required in my example. I'm worried about signal level
> > if a passive system (Mini Circuits divider or equivalent type)
> > is used.
> >
> > Would appreciate a few quick opinions on what is practical and
> > seems to work well.
> >
> > thank you in advance
> >
> > regards,
> >
> > skipp
> >
> > skipp025 at yahoo dot com
> >
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