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

Robert Atkinson robert.atkinson at genetix.com
Tue Jul 31 04:22:25 EDT 2007

Hi Jason,
The value of the capacitor is not critical in this case, anywhere from
47pF to 0.01uF. The series inductance and possible resonances are more
important. I used a small axial leaded multi-layer ceramic but any type
intended for high frequency de-coupling or RF applications should be OK.
Generally smaller is better. Ideally you would use surface mount devices
on a micro-stripline PCB, but its over-kill where we are only interested
in one frequency. You can't do much better without access to a network
analyser (or a lot of work with simpler equipment) or specialised RF

Robert G8RPI.

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Jason Rabel
Sent: 31 July 2007 01:31
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 at febo.com RETRY


Thanks, that's kind of the method I was thinking. I was just unsure of
capacitor to use. I have also seen in schematics where an inductor is
in series with the resistor to block the RF from going to ground (and
possibly causing screwy things I suppose).

I'm still waiting for the unit to arrive, when it does then I can figure
how I'm going to do all the connections and everything.


> Hi Jason,
> I had the same issue with a SatSync GPS. I got an old attenuator
> 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
> 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
> It seems to work OK.
> Robert G8RPI.

time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
and follow the instructions there.


Genetix Limited - Queensway, New Milton, Hampshire, BH25 5NN  Registered in England No. 2660050   www.genetix.com 
Any opinions expressed in this email are those of the individual and not necessarily Genetix Ltd (Genetix) or any company associated with it. This email and any files transmitted with it are confidential and solely for the use of the intended recipient. If you are not the intended recipient or the person responsible for delivering to the intended recipient, be advised that you have received this email in error and that any use is strictly prohibited. If you have received this email in error please notify Genetix by telephone on +44 (0)1425 624600.
The unauthorised use, disclosure, copying or alteration of this message is strictly forbidden. This mail and any attachments have been scanned for viruses prior to leaving Genetix network. Genetix will not be liable for direct, special, indirect or consequential damages as a result of any virus being passed on, or arising from alteration of the contents of this message by a third party.

More information about the time-nuts mailing list