[time-nuts] Building a DC Block Thingy....
John Ackermann N8UR
jra at febo.com
Fri Jul 27 21:44:29 UTC 2007
SAIDJACK at aol.com said the following on 07/27/2007 05:00 PM:
> I have one of these Tucker HP 8-ports GPS antenna amps/splitters too, and
> they are configured to only accept an external power supply, but can be easily
> modified:
>
> All you need to do is add a small inductor (say 33nH, 200mA) in the
> footprint that's reserved for it on the PCB. There is a location connecting the Port
> 1 center pin to the power input jack, and the 0805 component is simply
> missing from the PCB.
I thought about it and decided not to do that because I didn't want my
whole stack of receivers to be depending on Port 1 being connected.
With the external power, I still have a point of failure, but
accidentally turning off a GPS without remembering the consequences
isn't an issue.
> With this simple modification GPS Port 1 can supply power to both the
> antenna and the splitter/amplifier.
>
> At the same time it would be advisable to add a GDT (Gas Discharge Tube) or
> TVS against lightning proximity strikes.
>
> This can be done by adding another small inductor (33nH, 3Amps or better
> rating!) to the GPS antenna port, then connect that through the GDS/TVS to
> ground.
That's a good idea that I hadn't thought of...
John
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