[time-nuts] Building a DC Block Thingy....

[Robert Atkinson]

)

Hi Jason,
I had the same issue with a SatSync GPS. I got an old attenuator (burned
out or unknown spec), N type in my case but whatever matches your
splitter. I unscrewed it and removed the resistors. I placed a 0.001uF
63V ceramic capacitor between in and out and a load resistor (calculated
to draw just above the antenna warning current) between out (Rx side)
and ground. I did not feel this resistor would affect the signal too
much, but slipped a ferrite bead over the ground end lead just for luck.
It seems to work OK.

Robert G8RPI.

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Jason Rabel
Sent: 27 July 2007 21:53
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Building a DC Block Thingy....

); SAEximRunCond expanded to false
Errors-To:
time-nuts-bounces+robert.atkinson=genetix.com+robert.atkinson=genetix.co
m at febo.com

I have 2 other GPS devices already on the splitter, so there is really
no
need for any DC current to be passed as the splitter will just sink it.
I
just wanted to build an extra measure of safety in there sinking the 12V
before the splitter *incase* the other 2 GPS devices are turned off or
something happens.

Yes I'll probably plug in the NTS and check the power on the antenna
port,
if it stays at 5V then I can at least use it temporarily to ensure that
it's
working and everything.

I'll look into some of the mini-circuits stuff on eBay and see what I
can
find. I probably won't buy / build anything until the unit arrives. I
might
be able just to desolder a component and sink the 12V internally before
it
gets injected to the RF signal. But I don't want to cut any PCB traces
or do
anything that is irreversible.

Thanks for all your input guys and various solutions. :)

I'm surprised nobody said get a 12V antenna... lol. Does anyone have any
spare outdoor mast style they would sell (cheap)? I remember I saw some
on
eBay a while back, I'm sure more will pop up eventually.

Jason


> My first thought here would be to use a small 3 pin 5V regulator to
drop
the
> DC down, and then capacitively couple in and out to let the RF
through.
> 
> Interesting to see what other comments you get.
> 
> Rob K 


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