[time-nuts] filtering a 10Mhz frequency standard?

Robert Darlington rdarlington at gmail.com
Tue Dec 13 09:08:59 EST 2011


I just ordered the parts for this filter from Mouser Electronics.   ~ $30
plus shipping including a shiny new Pomona box.

qty 2 542-78F1R0-RC RF Inductors 1.0uH 10% @ $0.18 ea
qty 2 140-50S5-271J-RC Ceramic Disc Capacitors 50V 270pF SL 5% Tol @ $0.14
ea
qty 1 140-50S5-471J-RC Ceramic Disc Capacitors 50V 470pF SL 5% Tol @ $0.11
ea
qty 1 565-3752 Test Connectors SHLD BOX BNC (M/F) @ $29.12 ea (ouch!)

That's 75 cents in parts plus the box.  Once assembled I'll sweep it with
the network analyzer and report back on tweaks made to get it closer to the
simulation.

-Bob



On Tue, Dec 13, 2011 at 4:08 AM, <n1jez at burlingtontelecom.net> wrote:

> Paul's simple filter:
>
> http://www.w1ghz.org/small_**proj/small_proj.htm<http://www.w1ghz.org/small_proj/small_proj.htm>
>
> Mike
>
> ----- Original Message ----- From: "Bob Bownes" <bownes at gmail.com>
> To: <lists at lazygranch.com>; "Discussion of precise time and frequency
> measurement" <time-nuts at febo.com>
> Sent: Monday, December 12, 2011 10:11 PM
> Subject: Re: [time-nuts] filtering a 10Mhz frequency standard?
>
>
>
> Paul Wade did a paper on 10Mhz GPSDO filtering for Microwave Update in
> October. It is in the proceedings. I don't know if it is available
> elsewhere.
>
> Bob
>
>
> On Mon, Dec 12, 2011 at 9:17 PM,  <lists at lazygranch.com> wrote:
>
>> I think you would want to avoid crystal filters due to microphonics.
>>
>> I've found building good LCR filters harder in real life than on paper.
>> (I've done plenty of leapfrog active filters from LCR based designs.) I've
>> had to make a passive LCR for ADC testing and secondary (parasitic elements
>> of nonideal component) come into play. Nowadays I just buy COTS.
>>
>>
>> ------Original Message------
>> From: Chris Albertson
>> Sender: time-nuts-bounces at febo.com
>> To: Discussion of precise time and frequency measurement
>> ReplyTo: Discussion of precise time and frequency measurement
>> Subject: [time-nuts] filtering a 10Mhz frequency standard?
>> Sent: Dec 12, 2011 5:54 PM
>>
>> What is the best practice for filtering a 10Mhz sine wave frequency
>> standard? I've read that you can do more harm than good. Filter
>> parts (caps, resistors and so on) are all temperature sensitive. But
>> all those $40 Rb oscillators are putting out a pretty rough looking
>> sine wave.
>>
>> Are some types of filters better. I thought about a crystal filters.
>>
>> --
>>
>> Chris Albertson
>> Redondo Beach, California
>>
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