[time-nuts] 10 MHz Band-Pass Filter Needed

[Bruce Griffiths]

A crystal filter may not be a good choice for phase stability unless an
oven is used.
Some of the older frequency standards used crystal filters within an
oven to cleanup the output signal.

The limited crystal dissipation as may raise the phase noise floor of a
low noise OCXO significantly.
The implementation shown in AN9815 is particularly poor in this respect.

A low Q resonant LC filter using low tempco components will have greater
phase stability.
Whilst obtaining capacitors with relatively low tempcos is relatively
easy, the tempco of most off the shelf inductors is usually unspecified.

The significance of the increased phase instability and /or raised phase
noise floor depends on the application.
If one is multiplying the output to 10GHz then even minor temperature
fluctuations will be a concern.

Bruce

Darrell Robinson wrote:
> If you're simply looking for purity of signal maybe a crystal filter.
>
> Intersil application note AN9815 is interesting.
>
> Darrell
>
>
> ----- Original Message ----- 
> From: "Richard W. Solomon" <w1ksz at earthlink.net>
> To: <time-nuts at febo.com>
> Sent: Thursday, January 08, 2009 10:11 AM
> Subject: [time-nuts] 10 MHz Band-Pass Filter Needed
>
>
>   
>> The GPSDO I want to use has an output rich in harmonics. In some
>> cases that is good, but Murphy rules and in the application I have
>> today, it is not good.
>>
>> I need a 10 MHz Band-Pass Filter, Bandwidth is not critical, something
>> small with SMA connectors would be ideal, but I can live with BNC.
>>
>> Anyone have such a beast or know where I can get one ? I checked
>>     
> Mini-Circuits
>   
>> and choked on the price !!
>>
>> Thanks, Dick, W1KSZ
>>
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