Hello, I recently purchased a nanovna s-a-a-2 (hardware version v2_2, 50k-30ghz, owocomm design), and after around 2 weeks of work the measurements on the s11 port decided to malfunction.

At the time of the s11 port breaking a simple v dipole was connected to the s11 port of the analyzer, and the nanovna was plugged into a usb port on my computer, where i was getting my measurements from using vna_qt.
After the malfunction I tried the following:
1) inspect my sma ports to make sure the little spring contacts weren't bent or out of place
2) connected all the different types of calibration loads directly to the s11 port with no change in any parameter
3) I connected a regular sma connector to both ports at once and observed the s21 logmag value change, which seems to imply that something is wrong with the s11 port only
4) disassembled the vna to check if there was some obviously blown up component (there arent any, even under the metal shielding)
5) cleared

Please help diagnose and potentially fix this problem.

I attached 3 pictures of the analyzer: one with no connections, one with the 50ohm load, and one with an sma connector connecting the 2 ports.

Firstly any nano vna advertised as performing up to 30GHz is making false claims about its specifications.

Secondly it sounds like you didn’t discharge any static from the antenna before connecting the nano vna and have blown the input stage. You may have gotten away with just the input switch which is documented on wiki.
Further than that you should probably wait for Erik to respond once you have posted those pictures you said that you had attached, along with pictures of both front and back of your nano vna.

On Sat, Nov 16, 2024 at 02:17 PM, M0CNL wrote:

Further than that you should probably wait for Erik to respond once you have
posted those pictures you said that you had attached, along with pictures of
both front and back of your nano vna.

Erik has nothing to do with VNA products - he manufactures the tinySA... Th OP has a product which is an owocomm design.

Yes you are right, I had just spent a while reading posts between Eric and a couple of users on the tinysa site and had forgotten that I had switched sites before replying.
________________________________
From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of Roger Need via groups.io <sailtamarack@...>
Sent: Saturday, November 16, 2024 10:28:55 PM
To: nanovna-users@groups.io <nanovna-users@groups.io>
Subject: Re: [nanovna-users] Diagnose unresponsive ch1 port on the nanovna #repair #circuit #fix #hardware #internals

On Sat, Nov 16, 2024 at 02:17 PM, M0CNL wrote:

Further than that you should probably wait for Erik to respond once you have
posted those pictures you said that you had attached, along with pictures of
both front and back of your nano vna.

Erik has nothing to do with VNA products - he manufactures the tinySA... Th OP has a product which is an owocomm design.

My bad, the 30ghz was a typo, the s-a-a-2 goes up to 3ghz.
I am new to groups.io, so the pictures didn't attach properly. Hopefully they attach this time.
I will add more closeup pictures of the circuit board once I get the chance.

Also, the 5th point in my original message was 5) cleared the configuration of the vna

Is there any way to replace the blown up part, or is purchasing a new unit recommended?
Thanks!

Here are the pictures of the front and back of the circuit board of the nanovna in as high of a resolution as I can provide with the metal shielding removed.

It is possible that U551 has been damaged.

Is it possible to somehow verify that the U551 chip is the one causing problems?