Hi, I have newly completed the VNA and did some initial tests. It is build on a V5.1 PCB with all necessary precautions. The VNA seem to work as expected...
Hi Ferdi, My Part 1 PDF, pg 13 has info re expected harmonic and alias levels. I took a quick look at your BMP files and didn't spot anything unexpected. The...
Hi Paul, Thank you for the quick response. It sounds like everything seems to be as expected. I'll continue to evalute it. By the way, thank you for making...
Hi All For those interested in testing the performance of the N2PK VNA and also test how your callibration kits " behave" the R&S software, reading S2p files...
G'day all, Some time ago I recall seeing a post on this forum regarding the possible development of a transverter for use with the N2PK VNA on 23cm. Can anyone...
My venerable FT-1000D had developed low sensitivity on 160m and a bit less so on 80m. I finally put it on the bench and began troubleshooting. Alas, everything...
I am trying to get meaningful q measurements with my vna. Have tried both series and shunt and seem to get q of about 0.002 wiit a coil that measures 205 with...
Hi Gary The following URL is not answering your question but it may help. http://www.wetterlin.org/sam/SA/Operation/CoilMeasurements.pdf There's also lots of...
what is the impedance you get? Is the inductance reasonable? go back to first principles - see if the basic real and imaginary components make sense first Dave...
Hi Gary, Following Dave's comments, please post details of your VNA measurement - DUT description, test config, cal method, cal stds, F, measured Rs, Xs, Q,...
Sorry about the delay getting back, but have been busy today. The Q measurements were made using two Tektronics 10X attenuators and a shunt jig, This was...
Hi Gary, Thanks for the added detail and, obviously, a Q of 97 is more plausible than the 0.002 first reported! Q measurements are one of the most difficult to...
This is where RF-IV Test Head can shine. Mine with no LLC calibration is able to measure coil Q~300. I guess it is harder to make a coil with a higher Q, hi,...
Hi Gary, Beware printed circuit board. FR4 has quite large losses at HF and typical spiral coils fabricated on one side of the pcb rarely exhibit a Q of much...
Been playing with this and Paul is right on with the cal standard. Used a Microwave NO load with a adapter and now getting A near 260! Guess I better start...
The key thing to recognize about high-Q measurements is that, by the very definition of Q, you are trying to measure a resistance that is swamped by a far...
Thanks, Sam. And yes, I agree that BNCs have no business getting used in precision measurements like Q. SMAs connectors with the same part number being used...
Hi Jim, Good point about FR4/G10 dissipation. Sam and I have both recently measured FR4 dissipation factor (=1/Q) at about 2%. I think it's best to eliminate...
Built up a little better calibration resistor today and found a coil that had a ceramic form which measured 2.5uh and a Q of 250 with the 4342. It measures...
Paul, I think I came up with a good method to illustrate the essential difficulty measuring Q for high-Q coils. If you graph on a Smith Chart coils (simulated)...
Hi Sam, Your PDF looks good! You might also consider adding a plot to your Smith Chart for Q=-150. I have been asked several times now "Why are my measured Q's...
Hi Sam et al, One other thought - to put all this into a context familiar to most amateurs, |rho|'s of 0.9934 and 0.9950 for Xs=50 and Q=150 and Q=200...
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Art
KY1K@...
Feb 10, 2010 2:27 pm
I wanted to thank all for the discussion about coils made on G10 PCB's. I was just about to build a preamp for VHF which featured an inductor built with PCB...
Right you are, Claudio. I too have used transmission measurements for improved accuracy in low impedances measurements in that the dynamic range of the VNA is...
Not to go off into the ozone, but when you think about it, all VNA measurements are transmission measurements, followed by some mathematical transformation....
Hi Sam, ... I don't know if they have an official term either, but I called them High-Z and Low-Z 'bridges' respectively in my Part 2 PDF, pg 23. These are...
I've used the "low impedance" bridge at work recently - we needed to verify the change in impedance of a device with power level at a level beyond either the...
Yes, the terminology of "bridges" and "fixtures" sometimes makes these sound fancier than they are. A plain-old coaxial tee connector makes a nice "shunt...
