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Jog wheel switch causes problems
#parts
When I (try to) move a marker on the Nano screen (not PC) the jog wheel switch causes problems. It is too sensitive and starts to change frequency settings.
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Re: HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
In calibration for measurement and in measurement at RF frequencies, high-Z
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is far more difficult than a short or proper 50-ohm termination. Take 144 MHz and assume you are attempting to measure 1 kohm. There will always be present roughly 0.5 to 1 pf in the measurement. At 144 MHz, 0.5 pF = -j2210 ohms. This is over twice the real part even at 0.5 pF - a very small capacitor. True, the output impedance (if you will, resistance plus a small amount of several pF of capacitance) of an HF tube amplifier is very high, between 1000 and 4000 ohms (+/-). The pi-L network between the tube plates and the output to the antenna feedline matches that high-Z (and renders pure resistance) to 50-ohms. That impedance is not measured with a VNA but rather but by using standard Ohm's Law based calculations specifically tailored for determining the values of the matching network to enable maximum power transfer. 450 ohm ladder line is a real differential transmission line as is 300-ohm TV twin lead as are long parallel close-spaced ribbons of copper strip as are parallel copper traces on opposing layers of a PC board. I use parallel open wire transmission line between my home brew L-network matching network (a.k.a., "antenna tuner" - it does NOT 'tune' the antenna!!) and the feed point of my 450-foot long doublet. Works great as a relatively lossless transmission line and withstands high SWR with insignificant additional loss. Dave - W?LEV On Mon, Feb 17, 2020 at 3:47 PM Nels Nelsen <nels.nelsen@...> wrote:
My tube amplifier takes exception to your statement: --
*Dave - W?LEV* *Just Let Darwin Work* *Just Think* |
Re: HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
I'll tell you what I have done to test high impedance RF.
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I built myself a fixture PCB, you can see if here: One of the parts of the fixture PCB is a ZIF socket connected to two SMA female connectors. It is very useful for measuring leaded components. I calibrated the VNA (the one I designed and built) using the ZIF socket lever up for open circuit, a very short wire between two holes for short circuit, and a 1/4 watt 51 ohm resistor for load. The leads were trimmed to minimize the inductance of the resistor. At 1-30 MHz, I then could measure the impedance of a 10k ohm resistor. The results were accurate over the entire frequency range, between about 9800 to 10200 ohms. At 1-600 MHz, I could measure the impedance of a 1k ohm resistor. The results were between about 950 and 1050 ohms over the entire range up to about 550 MHz, where the resistance dipped slightly to about 900 ohms. Because I only use the SI5351A up to 200 MHz (as that's all its speced for), 600 MHz is the maximum frequency I can test with the third harmonic. Fifth harmonic and up tends to be useful mainly just for crude antenna measurements. On Mon, Feb 17, 2020 at 9:52 AM W1RS <Deflatermaus@...> wrote:
High Z is hard to obtain at RF. For parallel twin lead with #16 wire, the |
Re: Which firmware for AA contains the "Config" button
I'm a happy camper. Got the Hugen firmware flashed, ordered a 100 count pack of diodes from Amazon via next day Prime delivery and as of last night, I soldered one of those bad boys on and I now have a working battery gauge. Great little device! I've got one of the 3D printed enclosures around mine as well.
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Re: HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
My tube amplifier takes exception to your statement:
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"High Z is hard to obtain at RF. " The amp wants to know who do you think has been talking on 40 meters for the last 30 years? And the 450 ohm ladder line does not agree with your concepts of transmission line either. But I told them that I would talk to you on their behalf. So please be more open to all the work they do, OK ? :) All done now, I hope they settle back down. (-: Nels NE7LS On Mon, Feb 17, 2020, 6:52 AM W1RS <Deflatermaus@...> wrote:
High Z is hard to obtain at RF. For parallel twin lead with #16 wire, the |
Re: Android app cable not working!
Got the cable today, did NOT work. This is number two. This cable is
an OTG data cable USB-C (nanovna) ti Micro-USB (samsung android phone) NanoVNA Web App from play store says "no device found" when press connect. What the ^%$ to do now? Shouldnt any OTG data cable work??? Any advice appreciated! On Sun, Feb 16, 2020 at 4:06 PM Kayak via Groups.Io <kayak1176@...> wrote:
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Re: nanoVNA Maximum Impedance Measurement (Folded Dipole example)
A few weeks ago I decided to measure S11 of a few metox wire ended
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resistors and got the following results at 10 MHz. Nominal value Rp 50 50.5 100 99.85 180 181.7 270 267.9 390 386 470 466 1000 986 I was pleasantly surprised by my results. Phil G3SES On Sun, 16 Feb 2020 at 21:59, Larry Rothman <nlroth@...> wrote:
I removed the comma from the end of the message link below. It works now. |
Re: vna isolation calibration
Best results are to terminate both channels with a good 50-ohm load.
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However, this afternoon, I went through the full cal for other purposes and got -90 dB on return loss measurement to about 50 MHz once the cal was complete (NANOVNA-F). Dave - W?LEV On Sun, Feb 16, 2020 at 11:03 PM <nanovnauser@...> wrote:
Hi all am i correct in thinking that when i get to do the isolation cal,i --
*Dave - W?LEV* *Just Let Darwin Work* *Just Think* |
Re: [nanovna-f] HI-Z EVALUATUTION - MEASURED
Dave, next time, just try using courier fixed font for any tables. I find that usually works well.?
On Sun, 16 Feb 2020 at 5:37 PM, David Eckhardt<davearea51a@...> wrote: Let's just try a PDF attachment.? See attachment. Dave - W ?LEV On Sun, Feb 16, 2020 at 10:32 PM David Eckhardt <davearea51a@...> wrote: If the group.io messes with the formatting (which it likely -- *Dave - W?LEV* *Just Let Darwin Work* *Just Think* |
Re: [nanovna-f] HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
Let's just try a PDF attachment. See attachment.
Dave - W ?LEV On Sun, Feb 16, 2020 at 10:32 PM David Eckhardt <davearea51a@...> wrote: If the group.io messes with the formatting (which it likely -- *Dave - W?LEV* *Just Let Darwin Work* *Just Think* |
Re: [nanovna-f] HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
If the group.io messes with the formatting (which it likely
did....grrrrrrrr.....grrrrrr), can I attach an MS Word document??? Dave - W?LEV On Sun, Feb 16, 2020 at 10:29 PM David Eckhardt via Groups.Io <davearea51a= [email protected]> wrote: OK.....I just had to do it. NANOVNA-F measured data compared to the HP-- *Dave - W?LEV* *Just Let Darwin Work* *Just Think* |
HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
OK.....I just had to do it. NANOVNA-F measured data compared to the HP
8753C measured data. Subjects are: 1) 220-ohm 1/8-watt 10 % 2) 470-ohm 1/8-watt 5 % Both VNA's were calibrated SOL. Measurements were made by placing the cursor at the designated frequencies and reading the complex impedance from the Smith Chart (HP) and Saver (NANOVNA - F). I cut the resistor leads as short as possible and inserted them into their respective female connectors (NANOVNA-F: SMA Port 01.........HP 8753C: BNC at end of 50-ohm cable where cal. standards were placed). In both cases, the reflection measurement method was utilized. Measured data follows: *Frequency (MHz) * *220-ohm* *470-ohm* *NANOVNA-F * *HP 8753C* *NANOVNA-F* *HP 8753C* 49.5 197.3 - j15.9 209 - j19.7 456.1 - j20.5 464.8 - j17.1 144.0 206.9 - j20.6 109 - j19.7 451.4 - j58.2 466.9 - j17.8 299.6 198.1 - j18.7 193 - j9 415.3 - j105.1 429.2 - j17.2 403.9 186.9 - j17.1 190 - j6.7 405.2 - j108.5 406.3 - j115.6 700.0 182.2 - j17.2 188.5 - j8.9 320.1 - j174.0 413.1 - j178.3 955.0 180.2 - j18.0 181.2 - j2.2 265.2 - j192.7 273.9 - j153.4 Draw your own conclusions. My Own Conclusions: PRETTY DARN GOOD....NO.....EXCELLENT.....comparing $60 to $25,000++ (in its day). I do not own a Rig Expert but have used a couple. I'll take the NANO's any day over far more $$$ for "the others". And, these are portable. The HP 8753C is anything but portable!!!! Dave - W?LEV |
Re: nanoVNA Maximum Impedance Measurement (Folded Dipole example)
I removed the comma from the end of the message link below. It works now.?
On Sun, 16 Feb 2020 at 4:39 PM, hwalker<herbwalker2476@...> wrote: ? I agree with Kurt that the NanoVNA's inaccuracies above 300 ohms are not that bad.? I had the same frustrations with an HP Agilent 8753C Network Analyzer with 85046A S-Parameter Test Set. Once you get very far from 50 ohms its accuracy also suffers.? An HP applications engineer I contacted explained that's pretty much the nature of the beast for any low impedance 50 ohm VNA, and there's no reason to expect any more of the NanoVNA.? As Kurt said, the test fixture also plays an important part in measurement accuracy, especially above 1 MHz.? Flying leads test fixtures basically only work for quick checks in the kHz region. ? Erik wrote a Matlab script, /g/nanovna-users/message/7685?to?use an external bridge to calibrate the NanoVNA at other than 50 ohms, but I never saw any feedback from users who tried using it at 300, 1000, or higher impedances.? There were actually about 34 messages in the "Using an external RF bridge with NanoVNA " topic and I don't remember a definitive test procedure write-up coming out of it. - Herb |
Re: nanoVNA Maximum Impedance Measurement (Folded Dipole example)
I agree with Kurt that the NanoVNA's inaccuracies above 300 ohms are not that bad. I had the same frustrations with an HP Agilent 8753C Network Analyzer with 85046A S-Parameter Test Set. Once you get very far from 50 ohms its accuracy also suffers. An HP applications engineer I contacted explained that's pretty much the nature of the beast for any low impedance 50 ohm VNA, and there's no reason to expect any more of the NanoVNA. As Kurt said, the test fixture also plays an important part in measurement accuracy, especially above 1 MHz. Flying leads test fixtures basically only work for quick checks in the kHz region.
Erik wrote a Matlab script, /g/nanovna-users/message/7685, to use an external bridge to calibrate the NanoVNA at other than 50 ohms, but I never saw any feedback from users who tried using it at 300, 1000, or higher impedances. There were actually about 34 messages in the "Using an external RF bridge with NanoVNA " topic and I don't remember a definitive test procedure write-up coming out of it. - Herb |
Re: Android app cable question
Since my phone has a MicroUSB,. I just ordered this one. If it works, then
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I may try to find a way to update the wiki (?) so others can have one to go to directly. USB C to Micro USB OTG Cable, CableCreation 0.65 ft Type C Braided Cord, 480Mbps Compatible with MacBook (Pro), Galaxy S8, S9, S10, Pixel 3 XL, 2 XL, Android Devices, 0.2M/ Space Gray On Sun, Feb 16, 2020, 1:27 PM gary <w9td@...> wrote:
Yes, but I used this one |
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