[time-nuts] RF Mixers for oscillator comparison

[Arnold Tibus]

Bruce, 

fine, I will do what possible, but not this night anymore, it is very late already 
(early morning) ! 
Would be of high interest what others are experiencing.

Thanks a lot,

Arnold



On Mon, 20 Apr 2009 10:59:10 +1200, Bruce Griffiths wrote:

>Arnold

>They do have lower isolation than the phase detectors and the TUF mixers.
>However it would be well worthwhile measuring their dc offset, its drift
>and their phase noise.
>Its possible to mitigate the effects of lower isolation by using low
>phase noise isolation amplifiers.

>If you do this please make it available so that it can be used by others
>in making similar decisions.

>It would be useful if anyone else who can measure the phase noise of any
>mixers they have do so.
>In this way we can build up information on the phase noise performance
>of various mixers without having to purchase mixers for such measurements.

>Bruce

>Arnold Tibus wrote:
>> Bruce,
>>
>> Are such as
>>  SRA-1H or SRA-3H no possible candidates?
>> Such I have still somewhere in a drawer.
>>
>> Arnold
>>
>> On Mon, 20 Apr 2009 10:25:28 +1200, Bruce Griffiths wrote:
>>
>>   
>>> Arnold
>>>     
>>
>>   
>>> Some of the early equipment produced by NIST used mixers from a company
>>> that eventually became into Minicirucits.
>>>     
>>
>>   
>>> Suitable candidates from the Minicircuits range are:
>>>     
>>
>>   
>>> TUF-1H+:
>>> http://www.minicircuits.com/pdfs/TUF-1H+.pdf
>>>     
>>
>>   
>>> This mixer doesnt have isolated RF, LO and IF grounds so external
>>> transformers would be rrequired.
>>> It  does have somewhat higher port to port isolation than most mixers.
>>>     
>>
>>   
>>> The minicircuits phase detectors such as:
>>>     
>>
>>   
>>> http://www.minicircuits.com/pdfs/RPD-1+.pdf
>>>     
>>
>>   
>>> http://www.minicircuits.com/pdfs/MPD-1+.pdf
>>>     
>>
>>   
>>> are worth considering, at least they have separate RF and IF grounds, a
>>> high maximum output as well as low dc offset and offset drift.
>>>     
>>
>>
>>   
>>> All of these are below $US25 (at the source).
>>>     
>>
>>   
>>> The phase detectors are perhaps the safest option however measurement of
>>> their phase noise would be advisable.
>>>     
>>
>>   
>>> Bruce
>>>     
>>
>>   
>>> Arnold Tibus wrote:
>>>     
>>>> On Mon, 20 Apr 2009 09:03:36 +1200, Bruce Griffiths wrote:
>>>>
>>>>   
>>>>       
>>>>> Corby Dawson wrote:
>>>>>     
>>>>>         
>>>>>> Arnold,
>>>>>>
>>>>>> Look at the top of page 3 on the link below. Not sure how they arrived at
>>>>>> their conclusion but there is one opinion on the HP mixers!
>>>>>>
>>>>>> http://www.unusualresearch.com/AppNotes/TimeNuts/OptDualMixer.pdf
>>>>>>
>>>>>> Corby Dawson
>>>>>> ____________________________________________________________
>>>>>> Debt collectors calling your house?  Click here to consolidate into one payment.
>>>>>> http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTIk3l9oQnolYGEY40TVwmsBD4opDDeVSRG36KHWHhZWexSiuRrXdm/
>>>>>>
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>>>>>>
>>>>>>   
>>>>>>       
>>>>>>           
>>>>> Statements about the low flicker noise of these mixers are sprinkled
>>>>> throughout the phase noise literature.
>>>>> Someone must have measured the phase noise of these and other mixers at
>>>>> some time.
>>>>>     
>>>>>         
>>>>   
>>>>       
>>>>> Its relatively easy to measure mixer phase noise:
>>>>> All one needs is a low noise preamp plus a sound card a 90 degree hybrid
>>>>> (or a suitable length of coax and a splitter) and a low noise source.
>>>>>     
>>>>>         
>>>>   
>>>>       
>>>>> However NIST papers often include a phase noise plot (attached) that
>>>>> illustrates that high level mixers can have a significantly lower phase
>>>>> noise than low level mixers (like the HP10514A).
>>>>> When choosing a mixer for this for phase noise measurement applications
>>>>> one may actually need to measure the phase noise characteristics of
>>>>> candidate mixers.
>>>>>     
>>>>>         
>>>>   
>>>>       
>>>>> Bruce
>>>>>     
>>>>>         
>>>> Wow, a good overview, Bruce! 
>>>>
>>>> But remain the questions: 
>>>> which are these high level mixers, are they readily available? 
>>>> Are they affordable? 
>>>> Perhaps not, why are they then not applied more often?
>>>>
>>>> Arnold
>>>>