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

Dr. Ulrich L. Rohde ka2weu at aol.com
Sun Jan 7 12:09:56 EST 2018

It is a Wien bridge....

Sent from my iPhone

> On Jan 7, 2018, at 10:33 AM, jimlux <jimlux at earthlink.net> wrote:
>> 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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