[time-nuts] AM vs PM noise of signal sources

Bob kb8tq kb8tq at n1k.org
Sun Jan 7 12:58:47 EST 2018


Hi

> On Jan 7, 2018, at 12:26 PM, jimlux <jimlux at earthlink.net> wrote:
> 
> On 1/7/18 8:05 AM, Arnold Tibus wrote:
>> Am 07.01.2018 um 16:33 schrieb jimlux:
>>> On 1/6/18 6:12 PM, Dana Whitlow wrote:
>>>> One point about oscillator design I've not yet seen mentioned is this: the
>>>> limiter
>>>> must not degrade the resonator Q when in action.  Hence, a pair of diodes
>>>> connected in parallel back to back, across a shunt resonator, would be a bad
>>>> thing to do from the perspective of low phase noise. A differential
>>>> amplifier
>>>> that limits by running out of current on peaks, driving a shunt resonator,
>>>> is
>>>> a much better way even though one pays a price in having more transistor
>>>> noise in the circuit.
>>>> 
>>>> I've long wondered if a very slow AGC might avoid the nonlinear mechanisms
>>>> issue except, of course, for things happening within the AGC loop's
>>>> bandwidth.
>>> 
>>>> 
>>> 
>>> That's the Wein bridge stabilized by a light bulb, popularized by Messrs Hewlett and Packard a while ago.
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>> Hello everybody, excuse me please,
>> but I see quite often mentioned the 'Wein bridge'. (Wein in german is 'vino' or 'wine' ;-)
>> Not of real technical importance, but shouldn't this not be correctly called a 'Wien bridge'?
>> As I know that this tricky circuit was developed by Max Wien in 1891.
>> Max Karl Werner Wien was a German physicist and the director of the Institute of Physics at the University of Jena at that time.
>>  (sorry, I am a nut ;-)  )
> 
> 
> 
> 
> 
> Ah yes. And I imagine then that the pronounciation should be in english “veen"

This time of year, it’s the word on the label right after the term Gluh. I tend to never / ever
get that one right either. It always comes out Glugh …. can’t think of why :)

The Wien bridge is a very “low Q” resonator approach. It will give you amazingly low distortion 
(low harmonics) at the same time it does pretty poor amplitude and phase noise. 

Bob


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