[time-nuts] HP3325B as LO for a transceiver or receiver? Phase noise?

Jeff Blaine KeepWalking188 at ac0c.com
Tue Jan 1 23:32:42 UTC 2019


I was doing some DR3 testing of receivers fitted with additional crystal 
filtering and at the time wanted to find a sig gen that was as clean as 
the pair of xtal oscillators which were the baseline.  Of course I never 
found anything that clean (at least not without spending a fortune) but 
do remember the 3325B was exceptionally clean close in.  The tradeoff of 
that as a source is that the noise floor does not roll off nearly as 
fast as something like an 8657b.  It lacks spurs close to the 
fundamental which are found in all the HP stuff of the age at least 
until you get to the 864x stuff.

The answer, as others mentioned, depends on what you are really trying 
to do with that rig though.  If you want a quick LO source then I would 
bet you will have a hard time showing the that rig's performance is 
suffering with the 3325B as the LO.  At least not without some pretty 
specific test criteria setup (e.g. DR3 testing vs. a pure xtal source).

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 01-Jan-19 3:33 PM, Artek Manuals wrote:
> The question that remains begging here from the original post (maybe 
> off topic ?) is how low a phase noise does he really NEED in this 
> application? We here at time-nuts tend to think in the 10e-12 minutia 
> area, but In this application ( a HF Communications receiver) the 
> 3325B  may be "good enough" that PN wont really be an issue as a 
> practical matter. Don't see who the original poster is from this 
> snippet but a possible better place to get a "practical" answer might 
> be over on the EEVBlog?
>
> Dave
> manuals at artekmanuals.com
>
>
> On 1/1/2019 3:38 PM, Brooke Clarke wrote:
>> Hi Chris:
>>
>> The HP 8648 Signal Generator was developed to have low phase noise 
>> that was needed for testing pagers.
>> See second table of SSB Phase Noise at:
>> https://prc68.com/I/HP8648.shtml
>>
>> -- 
>> Have Fun,
>>
>> Brooke Clarke
>> https://www.PRC68.com
>> http://www.end2partygovernment.com/2012Issues.html
>> axioms:
>> 1. The extent to which you can fix or improve something will be 
>> limited by how well you understand how it works.
>> 2. Everybody, with no exceptions, holds false beliefs.
>>
>> -------- Original Message --------
>>>
>>>    01/01/2019 14:22
>>>
>>> Could I use my HP3325B locked to a Trimble Thunderbolt GPS disciplined
>>> 10MHz oscillator as the master LO of my Kenwood TS-590S transceiver
>>> that has a LO at 15.6 MHz, or is the phase noise too great? My VK3HZ
>>> gps disciplened LO replacement died recently, I may be able to repair
>>> it but as they are no longer available I am looking at alternatives to
>>> achieve a very stable frequency. Thanks
>>>
>>> https://www.febo.com/pages/hp3325b/
>>>
>>> http://www.vk3hz.net/XRef/XRef_Home.html
>>>
>




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