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

[Don Collie]

3Tr`s can be very noisy - if the current drawn is constant, perhaps a 
decoupled resistor would be better..................................Don C.


----- Original Message ----- 
From: "Rob Kimberley" <rk at timing-consultants.com>
To: "'Discussion of precise time and frequency measurement'" 
<time-nuts at febo.com>
Sent: Saturday, July 28, 2007 7:33 AM
Subject: Re: [time-nuts] Building a DC Block Thingy....


> ); SAEximRunCond expanded to false
> Errors-To: 
> time-nuts-bounces+donmer=woosh.co.nz+donmer=woosh.co.nz at febo.com
>
> 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
>
> -----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 20:12
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] Building a DC Block Thingy....
>
> ); SAEximRunCond expanded to false
> Errors-To:
> time-nuts-bounces+rk=timing-consultants.com+rk=timing-consultants.com at febo.c
> om
>
> I have a NTS-200 on the way, but one thing about them is their GPS power
> output is 12V instead of the usual 5V. I really didn't want to modify the
> board any in an irreversible fashion so I was hoping to build an inline
> coupler that I could block / sink the 12V current.
>
> I have a Symmetricom SmartSplitter, and I know that *should* do the job as
> long as a lower numbered port is supplying power, but I really don't want 
> to
> take the accidental risk of sending 12V to my antenna.
>
> Doing the math to sink 25ma of current would require a 480 ohm resistor...
> That should make the receiver happy and think all is well. But that's as 
> far
> as my knowledge goes. What size capacitor would I need to use? Do I need 
> to
> add an inductor in series with the resistor?
>
>
> Jason
>
>
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