[OT] Splitting PPS?

Gary E. Miller gem at rellim.com
Wed Nov 13 23:12:38 UTC 2019

Yo Richard!

On Wed, 13 Nov 2019 16:42:37 -0600
Richard Laager via devel <devel at ntpsec.org> wrote:

> On 11/13/19 1:43 PM, Gary E. Miller via devel wrote:
> > Add a GHz power divider for $10 and run all 3 on one antenna.  
> So basically any splitter that has 3-4 outputs, e.g. SMA connectors,
> and a rating of 1-2 GHz (to cover the GPS bands)?

Pretty much.  All the cheap ones on ebay that are as you say have worked
for me, and others.  But triple check the pass band.
> Does this assume an unpowered antenna and GPS receivers that are not
> outputting DC power on their antenna port? Otherwise, if they are all
> trying to power an active antenna and are connected to the splitter,
> it seems like I might have a Bad Time and let the magic smoke out?

Some on ebay have DC blocks integrated, some do not.  Rarely is that
mentioned in the description.i  A very few have DC blocks on all but one
port.  Ebay stock rotates fast, and it is a crap shoot what you get
for DC characteristics.

For power splitters without DC blocks, I buy SMA DC blocks like this:


$8! So as much as the GPS!  Ouch.  Better to buy a $10 4 port splitter
that blocks DC.  Then use a power injecter (bias tee) between the
antenna and the splitter.  Like this:


Then I can swap GPS and the antenna stays powered.  Also allows me to use
older (12V) antennas.

Some GNSS receivers will still complain, they'll say the DC power is too
low.  Ignore that warning.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin
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