[time-nuts] Building a DC Block Thingy....
SAIDJACK at aol.com
SAIDJACK at aol.com
Fri Jul 27 21:00:29 UTC 2007
In a message dated 7/27/2007 13:10:12 Pacific Daylight Time, jra at febo.com
writes:
>I actually did just that on one of the HP 8 port splitters that was on
>eBay a few months ago. It was configured for external DC but simply
>passed the input voltage through untouched. A 78L05 regulator on a
>piece of perfboard mounted fairly easily inside the case and allows me
>to drive the splitter from my 13.8 volt bus.
Hi John,
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.
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.
I do not see any impact on sattelite SNR C/No with these two mods on my
system.
bye,
Said
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