[time-nuts] PN/AM and 1.5Hz spur from frequency doubling?

[Magnus Danielson]

Hi,

Considering that you have a diode and a tuned LC-tank, the tank will 
"ring" in it's own frequency, even if it is driven by the diode and 5 
MHz. This creates a single side-band tone which then shows up both as AM 
and PM. Well, that is my guess. 1.5 Hz is however very very close, which 
is quite impressive for 10 MHz, so there should be something more going 
on, I'm just speculating.

This gives some insight as one of many:
https://www.minicircuits.com/app/DOUB9-2.pdf
See the warning of over-power on last page.

MVH
Magnus

On 01/18/2017 06:01 PM, Bob Camp wrote:
> Hi
>
> Without seeing the circuit involved it’s a bit tough to guess all of the possible
> things that might be happening. One branch leads off to things like the circuit
> it’s self oscillating and creating the spur. Sub branches involve oscillation in
> a regulator at low frequency vs RF oscillation somewhere else. Another branch
> heads in the direction  of a loose cable running around the shop with a bunch
> of 10 MHz on it. There are many branches ….
>
> Bob
>
>> On Jan 18, 2017, at 11:13 AM, Anders Wallin <anders.e.e.wallin at gmail.com> wrote:
>>
>> I'm seeing +20-30 dBc/Hz of excess AM/PN, as well as a strong 1.5 Hz spur
>> created by frequency doubling from 5 MHz to 10 MHz.
>> https://goo.gl/photos/GFx9tQoxrSmyzUQo8
>> The input amplitude to the doubler should be just above the recommended 11
>> dBm.
>> What's going on??
>>
>> thanks!
>> Anders
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