开云体育

On Thu, Nov 28, 2019 at 06:14 PM, Dejan Corovic wrote:

This guy is really going deep into NanoVNA-H, finding some problems

The author of those articles Owen Duffy is very knowledgeable and I have learned a lot from reading his blog. Sadly he has a penchant for criticizing others and this detracts from his posts. What he says is thoroughly researched and he writes good posts but often at the expense of others.

Hugen seems open to constructive criticism of his design and makes modifications to his circuit to improve it. I applaud him for the way he strives to continually make a better product and look forward to his next design.

This guy is really going deep into NanoVNA-H, finding some problems

Dejan,
Could you reference where you read that the NanoVNA-H is full of hardware issues? The reason I ask is because the NanoVNA-H is hugen's latest release of the original NanoVNA and the only hardware changes he has made are slight improvements like adding a missing diode so that the battery voltage can be read, adding resistors for improved USB-C to USB-C connection, and putting the NanoVNA in a protective case.

I have both the original NanoVNA and the NanoVNA-H and have used them both extensively. The NanoVNA-H is the better value unless you can find the NanoVNA in the twenty dollar range.

- Herb

I want to buy NanoVNA but I am confused with so many vendors and versions of firmare.

I would like to buy on UK eBay so I can return it if it's clone. I read about most recent version NanoVNA-H that it full of hardware issiues.

Is there such a thing as an official NanoVNA hardware or manufacturer.

Who would be the most reliable seller on UK eBay or Amazon?

How to email you? the email address is blanked out after @.

When will the V2 design be manufactured and ready for sale? Any name yet for the product?

On Wed, Nov 13, 2019 at 04:16 PM, Larry Rothman wrote:

There is an interesting discussion on hugen79's NanoVNA Issues page on Github
regarding circuit changes/mods to reduce overall noise levels.

Gentlemen, what you have at Noise improvements.
Outlined in found that the power input at the mixer ICs is
lacking capacity, causing spikes and spur at 6.4 MHz (7.5 MHz at VK1OD) - unfortunately due to careless copying of schematic - or lack of quality control.
Namely, if you look carefully at edy555's designs - given the schematic drawings - there is clearly 100pF in parallel with 100nF on the 8th leg of the mixer ICs.
see edy555 build.gif and edy555 power input.gif drawings there is 100nF parallel 100pF.

73, Gyula HA3HZ

Free (in the USA) diodes available for battery indicator

I have 99 "extra" 1N4148WS diodes available.

If you want any, FOR FREE IN THE USA, send me a self-addressed stamped envelope and how many diodes you need. Email me for my address.

Roy K2RMA@...

hooray at last,the answer i needed,thanks eric 73

On Thu, Nov 28, 2019 at 05:40 AM, paul larner wrote:

yes they do,i need to know if i need the resistive touchscreen or the
capacitive one!

Unless I misread the diagram those displays have 40 pins.

Good luck on your search.

Did you check that they use the same controller?

On Thu, Nov 28, 2019 at 1:38 PM <erik@...> wrote:

Do the LCD modules you selected have 18 pin connectors as described in the
wiki?

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

Thank you,

Hans

-----Ursprüngliche Nachricht-----
Von: [email protected] <[email protected]> Im Auftrag von neb40gsm via Groups.Io
Gesendet: Donnerstag, 28. November 2019 11:55
An: [email protected]
Betreff: Re: [nanovna-users] nanoVNA Partner #nanovna_partner

Hi,

Thanks to all who appreciated the software. Consider it as my contribution to the group.

Kind regards,

neb

You need the resistive touch panel.

yes they do,i need to know if i need the resistive touchscreen or the
capacitive one!

Do the LCD modules you selected have 18 pin connectors as described in the wiki?

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

On Thu, Nov 28, 2019 at 03:12 AM, paul larner wrote:

Isnt it amazing how i cant get an answer to a simple question!,if i wanted to
use a tab i would have asked that!!,pointless as my tab doesent support the
app,just wanted to know what screen to get out of the 2 i linked too!.

Calm down Paul!

No one can tell you which one is better because it's personal preference.

Besides, there is only one person who attempted to change the display and that info is in the Wiki/Files section of the forum (Herman's work).

Now's the time to experiment - look at the specs and buy the display that matches the interface - simple.

Search the 7500+ messages - hopefully, you'll find more info.

John,

If you're sweeping an antenna that's in close proximity to the VNA,
leakage from the cables is probably not going to be a limiting
factor. Other aspects of cable quality (impedance bumps at
cheap connectors, as just one example) still matter. Another
very important aspect of cable quality is stability of the cable's
delay in the face of flexing the cable. If, for example, the cable
is flexed in between measuring the short and open CAL standards,
it can really throw off even single port calibrations.

You're right: really good test cables for VNA work would set you
back more than 10X the price you probably paid for your nano-VNA.
And a decent set of CAL standards goes for around $4k to $5k
last time I looked, which was close to 10 years ago.

I have access to a lab-grade VNA and have been meaning to
take a look at the cables that accompanied my Aursinc nano,
but haven't gotten around to that yet.

Dana

Hi aa_Talaat
Sort of right.
For the input impedance measurements you may calibrate Ch0 on the output side the inserted attenuator.
40dB is a bit tough as it will introduce larger measurement error/noise than if you used a 20dB attenuator which might not saturate the amplifier. I you have an oscilloscope/small signal power meter you may inspect the output or if you have more attenuator what the S21 output with 40dB versus 20dB in the TX path and if difference is 20dB then no saturation.
Kind regards
Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af aa_talaat via Groups.Io
Sendt: 28. november 2019 12:21
Til: [email protected]
Emne: [nanovna-users] Measure S11 and S22 for active devices

I build a common emitter amplifier based on BFP420 BJT, and would like to measure its gain and input and output impedance. As the gain should be within 25dB, so I connected a 40dB 50 ohm input/output attenuator between CH0 and the input of the amplifier to avoid driving the amplifier into saturation, then connected the output of the amplifier to CH1.

The negative dBs readings of S21 were making sense to me after adding up logically 40dB to come up with the actual amplifier gain. However as the inserted attenuator impedance at CH0 is 50 ohm, the readings of S11 was showing as almost flat 50 ohm across the frequency range which is expected.

To measure amplifier input impedance (S11), I removed the attenuator and connected amplifier input directly to CH0 and connected amplifier output to a 50 ohm load. As the amplifier is driven into saturation, I am not sure if the S11 readings are correct, and I can rely on for small signal.

I repeated the same but swapping the amplifier input and output to measure the output impedance (S22).

Is this the right way to measure input and output impedance for such amplifier.in the absence of power control on the nanoVNA? Is there a better way?

There is limited output power control on the nanoVNA you can use (limited, no 30dB control)
Use a terminal emulator to connect to the nanoVNA and you can use the "power" command to 4 levels of output power
power 0
is the lowest level,
power 3
the highest level
The levels result in 2, 4, 6 and 8mA into 50 ohm so the maximum current range you have is 8 / 2 = 4 , 4 times 4 (as you want the power range, not the mA range) gives you a factor 16 in power range

But for you amplifier this range is insufficient so I think you are using the right approach

W.r.t the negative reading, if you do a calibration of the thru with the 40dB attenuator in line (no amplifier) the new 0 level of S21 will help showing positive levels for you amplifier.
By not storing the updated calibration it is a real temporary measurement calibration and when the nanoVNA is reset everything goes back to normal.
Whether the saturated measurement of S11 makes sense depends on the type of input component in your amplifier.

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

I build a common emitter amplifier based on BFP420 BJT, and would like to measure its gain and input and output impedance. As the gain should be within 25dB, so I connected a 40dB 50 ohm input/output attenuator between CH0 and the input of the amplifier to avoid driving the amplifier into saturation, then connected the output of the amplifier to CH1.

The negative dBs readings of S21 were making sense to me after adding up logically 40dB to come up with the actual amplifier gain. However as the inserted attenuator impedance at CH0 is 50 ohm, the readings of S11 was showing as almost flat 50 ohm across the frequency range which is expected.

To measure amplifier input impedance (S11), I removed the attenuator and connected amplifier input directly to CH0 and connected amplifier output to a 50 ohm load. As the amplifier is driven into saturation, I am not sure if the S11 readings are correct, and I can rely on for small signal.

I repeated the same but swapping the amplifier input and output to measure the output impedance (S22).

Is this the right way to measure input and output impedance for such amplifier.in the absence of power control on the nanoVNA? Is there a better way?

Hi,

Thanks to all who appreciated the software. Consider it as my contribution to the
group.

Kind regards,

neb