I suspect it is something you can do as long as the undesired 0dBv signal is not correlated to the -160 dB signal with a synchronous system and averaging.
Now as to extracting a harmonic with that S/N ratio then a bridge is a better choice. As to the device under test's time delay, one could cheat a bit and use the frequency range from 1 to 1,000 Hz. But of course that is not what you meant. Besides even that cheat might not be enough.
So to accomplish the task I would lock two identical test oscillators to a master with one via a time delay (phase shift network). One oscillator would drive the device under test and the output would be compared to the other unit. To verify the accuracy one would then swap the test oscillators to confirm the result was the same and it was actually the device under test that was the variable.
The other method would be to slowly sweep the input oscillator in frequency and compare that to the output.
But quite simply I would use a two tone test and look for the sum and difference frequencies. But of course that is not practical on narrow band devices under test.
yes sub regulating composite op amp input op amp supply can be necessary at some performance level - a consequence of:
CiteSeerX — A General Relationship between Amplifier Parameters and its Application to PSRR Improvement
which I've been mentioning here for over a decade
the paper was critical in improving my understanding of composite circuits, particularly power supply bootstraping
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This is well and good but the goal seem to be a plug and play general purpose instrument with -160dBV resolution. I contend that even if you had that it would be difficult to use and trust the answers.
I suspect you could build a purpose specific software controlled gizmo to do the calibration and measurement as a reliable system. But as profitable project... Nah!
Where did that idea come from??
I asked for LP Filter topology to reduce an unwanted (harmonic) signal to -160dbv.
-Richard
Thanks again for the recommendation, Ed. My used copy just arrived. Maybe it's wishful thinking but I think the authors (DJ & JH) might have initialled this copy ... ???
_
Attachments
The oscillator thread, sorry. At some level the question makes no sense with any active circuitry involved.
That is good stuff Richard, David! So what do I need to do for my
Shibasoku 725D to perform at that level on the monitor port?
What do I need to work on?
Should I try it on my HP339A first? Or will I end up
in a waterboard situation? Probably not, I think I'm
over my fear of work on it, or for that matter anything
again. It took me a while though.
Mark, I didn't find your middle initial.
I did like your information there. In fact, what you did
and I think the second or third poster about having pots
and dailing in etc is how I got my amplifier gain up to
the required 22.
All the number crunching then in trying to see what would
work I just stopped, built the model, then ended using two
pot as rheostats in series, for 2,5K and 20K 2 watt pots. That was
for the Source Resistance. For the Drain Resistance I used a NOS
decade resistor box that I have to dial it in.
I eventually had to up the VDD voltage to +17 volts to get it to
work correctly. Finally I had my .1Vin and 2.2Vout working
the way it should.
Will that quasimodo help me level out the parasitics on some high
voltage high inductance transormers? I have to sweep to greater then
300kHz...I think up to about 500kHz then the harmonics should point
me to where the frequencies are that need assistance?
I adjust the shunt for the center of these frequencies,
if I read this correctly.
The gentleman who turned me on to this didn't have time to tutor
me on it but suggested some physics books to read and encouraged
me to research further as he did. He's got lot's more experience
than I have.
Some of his research is over at WorldFaco, he's from down under.
He applied this research to fixing his automotive ignition issues.
I'll post a link when I find it again. Currently he designed and built
a Faco eye machine for use in third world countries so that they can
fix their eye problems affordably. I spelled it wrong, sorry Dr. Hugo.
Here is they good Doctor's Electronics Page
Home Page
I see I'll be reading about his Tek2465b "intertrack" problems.
Very Interesting Find here about the problem....
Anyone with one of the old TEK mainframe scopes my want
to read about his problems found.
It's all good stuff.
Cheers,
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I will expect to see you on "Pawn Stars" selling such a great value added book. 🙂
Open the attachment to this post and look for the silkscreen lettering "SEP 2013". There it is.
Recommend you start a new thread in the Power Supplies forum with the title "SyncTronX inquiries about Quasimodo Bell-Ringer Test Jig"
You are a lucky man to have even found and then acquired the 725D. Unlike the Panasonics and others, it's monitor port is calibrated to the THD scale being used. Just put a QA400/401 on the monitor port.
The Panasonic VP-7722A etc is all auto switching internally with no front panel indicator as to which scale is being used..... the monitor port is uncalibrated. So, you have to add/mix a pilot tone of known level into the instrument to know what scale is selected for certain when using the monitor port.
THx-RNMarsh
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What is the inter-gate capacitance on a dual jfet compared to single for something like the BF862 or 2SK3557?
Well, for example, if the last opamp providing the LP freq output was an integrator (C or RC in vfb) would not the harmonics of that opamp also be reduced in the LP output? What do you think?
Maybe a more complex vfb filtering for faster atten rate? Or combo with simple passive afterwards, on the output.
-RM
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It took me about 1 hour; real experts can probably do it a lot quicker. Same amplifier, configured (a) as unity gain buffer; (b) as integrator:
Code:
N-Period=1
Fourier components of V(unitygain)
Harmonic Frequency Fourier Normalized Phase Normalized
Number [Hz] Component Component [degree] Phase [deg]
1 1.000e+03 5.953e+00 1.000e+00 87.76° 0.00°
2 2.000e+03 7.907e-03 1.328e-03 -142.27° -230.03°
3 3.000e+03 2.009e-01 3.374e-02 138.24° 50.48°
4 4.000e+03 8.391e-03 1.410e-03 -11.45° -99.21°
5 5.000e+03 1.826e-01 3.067e-02 -69.98° -157.74°
6 6.000e+03 8.520e-03 1.431e-03 123.58° 35.82°
7 7.000e+03 1.603e-01 2.693e-02 82.08° -5.68°
8 8.000e+03 7.552e-03 1.269e-03 -104.35° -192.12°
9 9.000e+03 1.330e-01 2.234e-02 -125.86° -213.62°
Total Harmonic Distortion: 5.754084%(6.259402%)
********************************************************************************************
N-Period=1
Fourier components of V(integrator)
Harmonic Frequency Fourier Normalized Phase Normalized
Number [Hz] Component Component [degree] Phase [deg]
1 1.000e+03 5.806e+00 1.000e+00 178.10° 0.00°
2 2.000e+03 1.594e-02 2.745e-03 -2.19° -180.29°
3 3.000e+03 1.536e-01 2.646e-02 84.59° -93.51°
4 4.000e+03 2.878e-02 4.957e-03 10.93° -167.17°
5 5.000e+03 1.350e-01 2.326e-02 99.78° -78.32°
6 6.000e+03 3.865e-02 6.657e-03 19.53° -158.57°
7 7.000e+03 1.152e-01 1.985e-02 110.66° -67.44°
8 8.000e+03 4.468e-02 7.695e-03 27.68° -150.42°
9 9.000e+03 9.478e-02 1.632e-02 120.30° -57.80°
Total Harmonic Distortion: 4.513268%(5.040482%)Interesting things start to happen when you dial down the harmonics of the base amplifier, the winner's trophy swaps back and forth a few times, but it "not much difference anyway" seems to hold true in all cases. Have some fun, give it a try yourself.
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