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I'm in the weeds reading this but what I do to verify a "working" battery is: charge it up and then put a calculated load across it while monitoring the battery health. i.e. choose a fixed load like

Yes, if yours it is a 2.8" NanoVNA-H, i have replace the LCD screen with a 3.2" version. This is described eirlier in the Files section. It was the only version that has fit on the 40p? flatcable.

VCC is 4.9 volts, but VDD starts out at about 2 volts when I turn it on and then drops below 1.7. Is U11 the likely culprit? I guess I could order one and find out how good my surface mount soldering

Thanks all for your advices and valuable guidance , very informative . Please did NANO-VNA H4 V4.3 has an STM32F407 microcontroler inside or STM32F10X ?? Did NANO-VNA H4 V4.3 has a reliable

First, which NanoVNA are you asking about? There are several different designs of the NanoVNA. Each may differ in hardware designs, that may require a specific display driver components as well as

Good Morning. I find that tethering the nanovna to a computer or notebook works quite well when used with either nanovna-saver or the RigExpert app called "AntScope2" which is available free (Windows,

You can't just swap in a larger screen because it will not be pin compatible. If you own a 2.8" you could buy a 4" model which is much easier to read. Or you can connect it to your PC using NanoVNA

It sounds like you may have a component failing on the board, probably in the power supply circuits. I would say to check the electrolytic capacitors, since a failing cap could cause this behavior,

Has anyone opened a nanovna to see if it has header plug-in pins to the screen? Can a larger screen be swapped on to one with a tiny screen? Otherwise I must use a magnifier to read it. I did a search

[email protected]> wrote: I’ve already done that. It makes no difference. I doubt the battery is the problem because it behaves exactly the same way with or without the battery connected. I'm

Take the battery out and run it on USB power. Roger

It could measure 4.1V but have high internal resistance. That would cause it to fail under load. I take it that the SA runs OK on USB power? "Jim Ancona N1ADJ via groups.io"

Currently mine runs for one second after I turn it on. Given that the battery measures 4.1 volts, do you still think it's a battery issue? Jim [email protected]> wrote:

Start from a fresh charge and see how long it takes to run the battery down and turn off. "Runtime test" is easier to type. :) Recharge it immediately when done. "Jim Ancona N1ADJ via groups.io"

[email protected]> wrote: What do you mean by a runtime test? I tried searching but didn't come up with anything. Thanks, Jim

I would say do a runtime test on it. That will tell you one way or the other. But do remember to maintenance charge it if you don't use it for a long period of time. It could also be crud in the power

I like the battery theory, but I measure 4.1 volts across the battery terminals with the unit turned on (battery is marked 3.7v) and the device behaves exactly the same way when plugged into the

You battery is likely bad. Lithium based batteries do not like to be deep discharged. It will kill them. The VNAs have a very small but finite current drain when powered off and need to be

That acts exactly the way I would expect a failed battery to behave, esp. since DFU mode does not eun anything that you flashed . . . Somewhat odd that it won't stay on if plugged in, but the charge

I've used my NanoVNA-H4 periodically for several years. Yesterday I charged it, then upgraded the firmware from NanoVNA-H4-SI_20211230 to NanoVNA-H4-SI_20211230. I re-calibrated and started doing some