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Re: Handling the nanoVNA h4
Hi again,
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Once you have added the ferrite material, check by putting the nano down, and picking it up again. If the frequency still slides around try increasing the number of turns until you see no, or little, change in frequency. Once you arrive at a point where you are seeing little, or no change in frequency, it is time to tune the antenna. 73, and thanks, Dave (NK7Z) ARRL Volunteer Examiner ARRL Technical Specialist, RFI ARRL Asst. Director, NW Division, Technical Resources On 7/9/23 13:24, Edward Stavin VE3VYT via groups.io wrote:
Interesting. So should I be sure to avoid contact with the nanovna while observing or tuning the antenna swr? |
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Re: Handling the nanoVNA h4
Totally depends on the design of your antenna.
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With something like a ground plane antenna, your had should do little. A Yagi antenna with a Balun, your hand should do little. HF Dipole with a Balun, your hand should do little. A long wire antenna or no Balun, yes, your hand would do quite a bit. Easy test.?? Kent On Sunday, July 9, 2023 at 03:24:32 PM CDT, Edward Stavin VE3VYT via groups.io <edwardstavin@...> wrote:
Interesting. So should I be sure to avoid contact with the nanovna while observing or tuning the antenna swr? |
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Re: Handling the nanoVNA h4
Hi,
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This indicates you have become part of the antenna system... It also indicates you might consider adding a good 1:1 choke at the antenna feedpoint, and try the test again. I would guess you will see less of a slide... See: for more on how and why this works... 73, and thanks, Dave (NK7Z) ARRL Volunteer Examiner ARRL Technical Specialist, RFI ARRL Asst. Director, NW Division, Technical Resources On 7/9/23 13:02, Edward Stavin VE3VYT via groups.io wrote:
Hi. I have set and calibrated the nanovna and then hooked up my antenna to see the SWR graph. Let's say I have a 20m antenna attached and it shows a nice dip at 14.45Mhz to swr of 1.2. all this time of course the device has been in my hand. |
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Re: Handling the nanoVNA h4
You were part of the resonate circuit of the antenna.
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You were a? Counterpoise! Virtually every talkie is depending on the operators hand to be the other half of the antenna. Kent WA5VJB?? Antenna Editor CQ Magazine. On Sunday, July 9, 2023 at 03:02:27 PM CDT, Edward Stavin VE3VYT via groups.io <edwardstavin@...> wrote:
Hi. I have set and calibrated the nanovna and then hooked up my antenna to see the SWR graph.? Let's say I have a 20m antenna attached and it shows a nice dip at 14.45Mhz to swr of 1.2.? all this time of course the device has been in my hand. Without moving my feet I put the nanoVNA on the nearby plastic chair and when I let go the dip slides left to 14.2Mhz. Is it normal to see different swr readings like this when holding or not holding the nanoVNA? Which is the correct reading?? Sorry for the newb question. Appreciate any input. Edward |
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Handling the nanoVNA h4
Hi. I have set and calibrated the nanovna and then hooked up my antenna to see the SWR graph. Let's say I have a 20m antenna attached and it shows a nice dip at 14.45Mhz to swr of 1.2. all this time of course the device has been in my hand.
Without moving my feet I put the nanoVNA on the nearby plastic chair and when I let go the dip slides left to 14.2Mhz. Is it normal to see different swr readings like this when holding or not holding the nanoVNA? Which is the correct reading? Sorry for the newb question. Appreciate any input. Edward |
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Re: Setting trace colors
To clarify, I mean from within the NanoVNA GUI itself, as what I found
requires using the console, which makes experimenting with colors difficult. References to change colors over the console: /g/nanovna-users/wiki/12760 /g/nanovna-users/message/23259 I also ask, because the firmware seems to be closed source and the wiki not updated to the latest changes. |
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Re: NanoVNA (Classic) or NanoVNA-H4 for filters, crystals etc.
On most firmware versions, the averaging or bandwidth settings can be manipulated to give longer settling time at each frequency step. This helps for narrowband devices.
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--John Gord On Sat, Jul 8, 2023 at 05:37 PM, Jim Lux wrote:
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Re: NanoVNA (Classic) or NanoVNA-H4 for filters, crystals etc.
On 7/8/23 3:57 PM, Ma?l H?rz wrote:
Hello,Without getting into the details of the various firmware versions, if you're measuring high Q devices (like crystals), then using one of the NanoVNAs with a computer running software that lets you have a lot more points is quite useful. The problem with high Q is that the NanoVNA only samples for a millisecond - that is, it switches the stimulus and receiver frequencies to the next step, then delays a *short* time to let the synthesizers lock, then measures for a millisecond. If the thing you're measuring has a time delay, or takes a while to settle, then the measurement won't be as accurate. The "time constant" for a resonator (i.e. the time for the energy to decay to 37%, 1/e) is Q radians. Since one cycle is 2pi radians, the number of radians is 2*pi greater. So Q/(2*pi) is the number of cycles, each of which is 1/f, so after Q/(2*pi*f) seconds, the energy will be 37%. (down 4.3 dB) If your resonator has a Q of 5000, and resonates at 10 MHz, we can run some numbers: 5000/(2*pi*10E6) = about 0.08 milliseconds - so probably not a big deal. I've not thought about what phase error one would get from the delay, though. |
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NanoVNA (Classic) or NanoVNA-H4 for filters, crystals etc.
Hello,
I have read various sources on the Internet and it seem that the classic NanoVNA is best suited for testing filters (below 300 MHz) and measuring crystals. It also seems that the DiLord firmware for NanoVNA-H (not H4) can be used on the original NanoVNA. Does that mean NanoVNA and NanoVNA-H have similar performance. What about NanoVNA-H4? I read it does have worse performance for this application (<=300MHz) and measuring filters/crystals. But I would prefer its larger screen. I thought about additionally getting the LiteVNA for its larger bandwidth, but apparently the noise floor for lower frequencies is worse than the original NanoVNA (what about NanoVNA H-4)? I could not find any info about the RBW of NanoVNA (original), NanoVNA-H, NanoVNA-H2, or LiteVNA. My main interest is really testing lower frequencies, as mentioned above. Any clarification would greatly help. What I find on the Internet is kind of confusing between various firmware versions and upgraded version of the various models. Best regards, Ma?l H?rz |
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Re: NanoVNA-H4 | SWR spikes non only at 300MHz, but also around 500 MHz
On 7/7/23 2:08 PM, Andrea I2UEA wrote:
Did it, but unfortunately it didn't work: same condition at 300MHz.Yes, very much so There are two effects to be aware of: 1) if the signal is close to the test frequency, it makes it through the receiver. Broadcast FM is pretty wideband - the VNA's receiver is about 1 kHz wide, so if you're sweeping across that band, you'll likely get interference 2) saturation of the receiver. I can't remember what the max input before saturation is, but considering that the VNA puts out around 0 dBm, and with a short, all that comes back to the receiver, 6dBm probably won't saturate the mixer. |
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Re: NanoVNA-H4 | SWR spikes non only at 300MHz, but also around 500 MHz
Did it, but unfortunately it didn't work: same condition at 300MHz.
Is really the SI5351 generator overheating? The problem appears even when the device is just switched on. Additional question: I live close to the centre of Milan and I receive very strong signals, especially from FM broadcast stations, receiving levels around + 6dBm (yes: 0,44 V !!!) or so. Can they affect the masurements? |
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Re: NanoVNA-H4 | SWR spikes non only at 300MHz, but also around 500 MHz
si5351 generator overheating and not stable work near top limit
Need reduce threshold to 295MHz, save config, recalibrate This solve problems in 290-310MHz Others threholds - only fixed inside firmware Try add radiator on SI5351 generator |
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NanoVNA-H4 | SWR spikes non only at 300MHz, but also around 500 MHz
Hi, I am sure that almost 3 months ago, when I measured my Log Periodic antenna Create-5130-1N, its SWR was almost perfectly flat in all the 50-1300 MHz range. However I am now seeing strong and variable spikes in a whide band around 300 MHz which, if I properly understood, might be probably fixed by changing the setting CONFIG - EXPERT SETTINGS - THRESHOLD. However I am also seeing the same problem around 500 MHz as per attached images. Please note:
1) I didn't change anything in my NanoVNA-H4, apart updating the firmware 2) After updating the firmware I re-calibrated my unit 3) I am seeing the same spikes even by measuring my 2m/6m/70cm vertical antenna (Diamond V2000A) 4) No problem if I measure a 2m/70cm portable antenna What can I do? Thank you for your comments and help. |
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Re: nanoVNA-H net com usb port
- working update methods for me:
I have original devices, - I always like to use the STM32CubeProgrammer One device (I think not important which one) by the tray icon (same like usb drive) shows me: STM32 BOOTLOADER - at the same time in Device manager: STM Device in DFU Mode (Yes, - I didn't mix up the description!) - at the same time in STM32CubeProgrammer at port: No DFU detected... but with the aplication; the FW upgrade working. Here is the link: On the same computer one other device (I think not important which one) by the tray icon shows me: STM32 BOOTLOADER - in Device manager also: STM32 BOOTLOADER the STM32CubeProgrammer see at port: USB1 - then possible to connect, and making a FW upgrade Istvan |
Andrea I2UEA
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