[time-nuts] Phase noise measurement (was - no subject)

[Bob Camp]

Hi

One thing to head back to here:

What is being measured?

If the DUT is "only" as good as a 10811 and you have a 3561a, an AD797 is overkill. That assumes you are running a RPD-1 or a high level mixer with buffers. There aren't a lot of oscillators on the surplus market that will need much better.

Super amps are fine. They just are a bit beyond the minimum required to get going.

Bob




On Aug 21, 2010, at 3:47 PM, Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:

> EWKehren at aol.com wrote:
>> Thanks   Bert
>> 
>> 
>> In a message dated 8/21/2010 11:43:53 A.M. Eastern Daylight Time,
>> dk4xp at arcor.de writes:
>> 
>> 
>>   
>>>  Wenzel Audio Amp referred to in this email. Perfect! I drive with it a
>>> 3561A and  a 7L5!  Works for me.  The only problem is  getting any more
>>> 2SK369.
>>> Any  recommendations?
>>>     
>> NXP   BF862, available from  digi-key.
>>   
> Don't these devices have relatively high flicker noise?
> 
>> I have used it in a similar hookup with good success. Its  virtue is the
>> low noise voltage AND low input capacitance at the same  time.
>> You could deploy MANY of them in parallel until you get
>> into the  capacitance range of a single Interfet device.
>> 
>>   
> The input capacitance is relatively noncritical in this application (phase noise measurement) since it is shunted by the much larger output capacitance of the low pass filter at the mixer IF port.
> 
>> One heroic effort for  audio is here:
>> http://www.diy-audio-engineering.org/index.php?board=2.0   HPS5.1
>> 
>> I currently use 3 pairs of SSM2210 in front of a  AD797.
>> 
>> regards,  Gerhard
>> 
>>   
> 
> Bruce
> 
> 
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