[time-nuts] OXCO Spurious Output at Line Frequencies

[Alan Melia]

Bob the VLF guys in Europe can receive the 60Hz signal over here! so you 
probably needed a test site on the far side of the Moon :-))
Alan
G3NYK

----- Original Message ----- 
From: "Bob Camp" <kb8tq at n1k.org>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Tuesday, July 12, 2016 10:53 PM
Subject: Re: [time-nuts] OXCO Spurious Output at Line Frequencies


> Hi
>
> The “practical” solution often is to ship it to an office of the same 
> company that happens
> to have 60 Hz power. The spur moves to 60 / 120 / 180 and they move on 
> with their
> evaluation.
>
> I have also played the “let’s do it with batteries" approach. Screen rooms 
> were of little benefit.
> Simply running test gear on batteries did not do the job. Ultimately we 
> wound up in the
> middle of an Illinois corn field with a bunch of gear modified to run 
> purely on batteries. The
> spur did go down, but it never fully went away.  It’s been 40 years since 
> that adventure so I
> really could not say just how far down we got it ….
>
> Anything past -120 db at line frequency is in the “don’t bother” category.
>
> Bob
>
>
>> On Jul 12, 2016, at 6:44 AM, Martyn Smith <martyn at ptsyst.com> wrote:
>>
>> Hello,
>>
>> I have a customer who is measuring the phase noise of my 10 MHz ultra-low 
>> phase noise frequency standard.
>>
>> He is seeing spurious signals at line frequencies (50 and 100 Hz as we 
>> are in Europe) at a level around -130 dBc.
>>
>> My opinion is that it's impossible to get much better than that.  Even 
>> running on batteries make little difference, since the equipment is in a 
>> test rack with AC signals everywhere.
>>
>> Even the £50k R&S test set he is using only quotes a spurious spec of -90 
>> dBc.
>>
>> What experience does anyone have here?
>>
>> Best Regards
>>
>> Martyn
>>
>>
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