[time-nuts] Close in phase noise of microwave VCOs
kb8tq at n1k.org
Thu Jun 18 21:52:35 UTC 2015
If you get down to 1 Hz or below on a wide tune microwave VCO, the noise in a “normal” battery may
be a problem. NIST has some pretty good papers on this. Unless a power supply is specifically designed with
a wide tune / microwave device measured unusually close in, it’s probably not going to be good enough.
Does it all depend on just how sensitive the VCO is, and how quiet it “really” is, and several other things? sure.
One of the reasons you rarely see data this close in is the difficulty with power.
> On Jun 18, 2015, at 2:47 PM, Brooke Clarke <brooke at pacific.net> wrote:
> Hi Bob:
> The DC supply in the HP 4352 VCO test set is very special in that it's output voltage has extremely low noise.
> Another option is to use a battery(s) for the control voltage.
> Mail_Attachment --
> Have Fun,
> Brooke Clarke
> Bob Camp wrote:
>> Be careful when you do find the data.
>> When you go very close in on something like a VCO, you get much higher phase noise
>> than we normally worry about. Some of the “assumptions” that underly the measurements
>> are no longer true. Small angle of modulation is one, but there are a few others. A simple
>> “plug it in and read it” may not give you valid information without some corrections. Coming
>> up with a supply that’s good enough (at 1 Hz) would be a major challenge ...
>>> On Jun 17, 2015, at 11:23 PM, Jim Lux <jimlux at earthlink.net> wrote:
>>> On 6/17/15 1:08 PM, Magnus Danielson wrote:
>>>> John Miles have been a bit active:
>>>> Just to give you a start-sample.
>>> those seemed to be all PLL outputs.. I didn't see the bare VCO data.
>>> And, I'm really interested in the 1 Hz to 100 Hz kind of range.
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