reflection phase shift off of a simple resonator looks like this:Hello biff44,i have some question to better understand your explanantion:
1.the main oscillator gets a signal from the YIG .The oscillator sends back a signal with an amplitude depending on the oscillator resonance.
regarding what you say about the "angle" below.by angle i understand that the phase also changes when we move away from the resonant frequency?
Why do you say that the phase of the reflected signal will change?
" the reflection coefficient angle of the Q=59000 resonator is ZERO degrees."
2.So what is the logic of putting this carrier nulling section if need to compare the YIG RF signal with the main oscillator RF signal?
"carrier nulling section that removes the carrier and only lets the noise sidebands come out of the mixer output So it will not be so simple to tune the yig oscillator until the mixer output is Zero Volts DC, since there is no carrier to generate the null!
3.regarding the servo amplifier how do you propose me to check in my lab the my servo amplifier will succeed in doing the locking.
i can record the signal coming out of each device. also i can create a transfer function
how do you propose me to convert this recorded data into a simulation?
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Sure about this? The point isn't discussed in original paper but I think it's necessary to zero carrier leakage in circulator which is typically higher than -36 dB minimal reflection from resonator.Carrier nulling section is not necessary. it is typically only used with high power oscillators, where they would blow out a mixer used as a phase detector
CC excitationHello Mr.Stewart,what is "over excitation" for a YIG.how this phenomena happens?
Also Biff44 said i should use capacitors,what capacitors do you reccomend?
do you reccomend to use ferrite beads?
Thanks.
There's obviously an unwanted modulation. Presentation of results suggests that you are not familiar with systematic debugging of this kind of problems. Test setup isn't shown clear enough to see all possible causes. Generally you should consider:Could you please say what could cause such bad outputs from the YIG?
I believe this is your hysteresis from the I in YIG. ( although I have never tessted any myself) It should be present when the modulation crosses thecenter of the hysteresis loop. Iron has hysteresis but much smaller in the YIG crystal but large compared to your PLL loop BW. The fourier spectrum with phase can be interpretted mentally or the time domain signal can see it in zero span mode in a time sweep if it is AM or on the edge of the IF filter if it is PM or FM.Hello, i have made a system to test the YIG. The tune is constant while the the FM coil is powered by the driver circuit we talked about before.
The tone goes from left to right.The big problem is as you can see below ,while its scanning sometimes i see relatively good signal some times i see the signal with two tones near the main,as shown below.
As i see it i have a problem with my YIG .
Could you please say what could cause such bad outputs from the YIG?
Thanks.
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He was one of those rare genius type engineers, who thought it was their duty to bring along the next crop of engineers to take his place. a great guy, easy to get to know.Galani was famous at Raytheon, although I never knew him. I have worked with similar designs 40? yrs ago (I forget) using the PD he used in the 90's patents with YIGs.
Was that called "Active Q" where loaded-Q is normally lower than Qu (unloaded) from damping.He was one of those rare genius type engineers, who thought it was their duty to bring along the next crop of engineers to take his place. a great guy, easy to get to know.
the genius of those noise degeneration synthesizers was, instead of finding the worlds highest Q resonators and somehow making them tunable, you instead took a resonator with a good Q, and virtually amplified its "effective Q" it by ~25 dB using cheap op amps in the control loop. It also fixed a lot of vibration issues
yes i have a couple of those HP8662/3s still. Fractional N synthesizers before you could BUY a fractional N chip! HP was a great innovator!Was that called "Active Q" where loaded-Q is normally lower than Qu (unloaded) from damping.
My 1st office computer was the HP9825 which could talk to a few RF, TIA and power instruments in a rack with HPIB in the lab in 1977. I learnt how make a SCADA system for remote testing all the instruments in a rocket. But then a SW radio caused burps on the RS485 LTDS datasets a mile apart between my HP9825's
Thgat was when I did 2 week stints up in Churchill NRC Rocket range. I was blown away by a hundred racks of 19" instruments for telemetry and a bunch of quad helix servo trackers etc. , literally wall to wall racks on 19" floor to ceiling.
Yes I think HP invented those methods on Saphire Oscillators for wide tuneability and OCXO's for low phase noise., I read he figured out to do that with lower Q YIGs .
Then HP also developed those too. I loved using the earlier versions of the HP9674A in the late 70's.
https://www.keysight.com/ca/en/assets/9018-05514/service-manuals/9018-05514.pdf I think this service manual will be of great interest to @yefj (600 pages with YTO)
Now Ebay sells them for $650 hah. I loved the roller dial with inertia. We would double the frequency output with a diode adapter when needed.
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I wish I had met Galani but I never interacted with Raytheon. ( no security clearance for non-residents)
yes !yes i have a couple of those HP8662/3s still. Fractional N synthesizers before you could BUY a fractional N chip! HP was a great innovator!
Yes, the whispering gallery mode saphire resonators were the pinnacle, some smart australian company patented their use.
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