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

Since the spur moved in frequency when the amplitude of the 25 MHz interference changed, my guess is that you have some grounding or cable leakage issues which are causing the measuring system to produce erroneous results due to overloading. Do you have all instruments and sources plugged into the

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

Hi I would bet that the spur moving is an indicator of either the 25 MHz transmitter carrier or modulator drifting in frequency. My guess is that the Maser does not drift :) Bob > On Jan 20, 2017, at 12:22 PM, Anders Wallin > wrote: > > I made some progress with

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

I made some progress with this issue today. It turns I was using a 75Ohm cable at some point (doh!) which caused a 'forest' of spurs far out. Possibly our other maser has a faulty/cut cable which behaves similarly. The final fix was to turn off our 25 MHz radio time-code transmitter which was

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

Thanks for all the comments so far. I will try the doubler with another quieter source, and try removing various potential noise-sources and exchanging cables... I have now uploaded a few more images of the same data to the shared album linked in my earlier post. Anders On Thu, Jan 19, 2017 at

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

I see spurs at 50 Hz and harmonics, which I assume are from the power line at your location. This might be due to an oscillation in the power supply regulator, leading to nonlinear regulator operation and feedthrough of power line ripple. For example, low dropout regulators can sometimes oscillate

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

You may find that the behavior varies quite a bit depending on what you put between the maser output and the doubler. I've seen one case in particular that generates a ton of PM spurs, specifically an HP 11721A doubler driven by the 5 MHz output of a 5061A Cs standard. The 5 MHz output uses a

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

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

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

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

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

Hello, can you share also the Phase Difference trace? cheers, Mattia 2017-01-18 17:13 GMT+01:00 Anders Wallin : > 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. >