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

Bob Camp lists at rtty.us
Fri Aug 20 18:42:25 UTC 2010


Sounds like that's less than $100 on a home brew basis.

There are several variations you could try. None of them break the bank. All do a quadrature test on a pair of OCXO's.


On Aug 20, 2010, at 2:17 PM, "Rick Karlquist" <richard at karlquist.com> wrote:

> Mark J. Blair wrote:
>>> oscillator inside a Tbolt then I don't think that a frequency
>>> discriminator will be sensitive enough, although I might be wrong.
>> I got the impression that for "good" OCXOs like the HP 10811 or
>> (supposedly) the OCXO in my TBolt, the delay line method wouldn't provide
>> enough sensitivity for measuring close-in phase noise.
> Right, the delay line method is a non-starter.
>>> Despite what you said, you might want to consider buying an HP 10811
>>> oscillator or similar which you could use in a phase detector
>>> measurement system which is likely to give superior results.
> On the 10811 production line, they would use Anzac AMC-123 amplifiers
> to drive a +17 dBm mixer, and then amplify the IF output with a low noise
> current amplifier like the Linear LT1028.  You can easily homebrew
> this setup.  You will need to have a DC coupled connection to the IF
> output to make a narrow PLL that drives the EFC of one of the oscillators.
> You can use a PC based audio spectrum analyzer program to look at the
> phase noise output.  You can break the PLL to get a beat note to calibrate
> the system.  The AMC-123 can also be homebrewed by reading the
> patent, which is listed on the data sheet.  No need at all to get
> a 3048, etc.
> Rick Karlquist N6RK
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