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On October 3, 2022 8:06 AM Reinier Gerritsen <r.gerritsen@...> wrote:


Working on 900 MHz patch antennas (copper foil for tuning and matching) with about 1 or 2 meter of coax to the (original) SAA-V2, I had 3 broken units (1 from my customer). All revived by replacing the switch ic directly at the input. Search in the nanoVNAV2 group for details on repair and how to add protection.

Success, Reinier

On October 2, 2022 5:24 PM linhz0hz@... wrote:


I am interested if anyone figured this out, because I just fried mine nanoVNA SAA-2N just now. -_-!

I was building some homebrew amplifier. Before measuring that, I wanted to calibrate the test PCB before I put in my transistor. So I would solder different resistors on the board and take measurement. The board is not powered (completely passive).
It was tedious, I got lazy and did not remove my nanoVNA while I solder. I had DC-blocking capacitors though and I got away doing that a few times before so I imagined it would be fine.

But apparently it is not fine this time. Now if I just connect Tx to Rx port, I got high reflection (close to an open) and only -20dB transmission. Software part seems to work still, so I suspect RF front end was killed. I open the casing and took a look, but I don't want to make a rush decision and break it further. Also those EMI shields looks hard to remove.

So does anyone have advice for me on what is the most efficient way to repair? And do you expect a soldering iron to have damage like this (I still don't fully believe it!) or is this something else?

On October 2, 2022 5:24 PM linhz0hz@... wrote:


I am interested if anyone figured this out, because I just fried mine nanoVNA SAA-2N just now. -_-!

I was building some homebrew amplifier. Before measuring that, I wanted to calibrate the test PCB before I put in my transistor. So I would solder different resistors on the board and take measurement. The board is not powered (completely passive).
It was tedious, I got lazy and did not remove my nanoVNA while I solder. I had DC-blocking capacitors though and I got away doing that a few times before so I imagined it would be fine.

But apparently it is not fine this time. Now if I just connect Tx to Rx port, I got high reflection (close to an open) and only -20dB transmission. Software part seems to work still, so I suspect RF front end was killed. I open the casing and took a look, but I don't want to make a rush decision and break it further. Also those EMI shields looks hard to remove.

So does anyone have advice for me on what is the most efficient way to repair? And do you expect a soldering iron to have damage like this (I still don't fully believe it!) or is this something else?

? If you measure capacitance between the AC cord to the Iron tip, you get about 200 pf.
The AC voltage is capacitively coupled to the Iron tip unless you have a specially grounded IRON,(And have the Ground Connected)
So the average soldering iron is a 200 pf cap plugged into 120 VAC going to your circuit.? Kent

? ? ? On Sunday, October 2, 2022 at 05:33:28 PM CDT, <linhz0hz@...> wrote:
?
? I am interested if anyone figured this out, because I just fried mine nanoVNA SAA-2N just now. -_-!

I was building some homebrew amplifier. Before measuring that, I wanted to calibrate the test PCB before I put in my transistor. So I would solder different resistors on the board and take measurement. The board is not powered (completely passive).
It was tedious, I got lazy and did not remove my nanoVNA while I solder. I had DC-blocking capacitors though and I got away doing that a few times before so I imagined it would be fine.

But apparently it is not fine this time. Now if I just connect Tx to Rx port, I got high reflection (close to an open) and only -20dB transmission. Software part seems to work still, so I suspect RF front end was killed. I open the casing and took a look, but I don't want to make a rush decision and break it further. Also those EMI shields looks hard to remove.

So does anyone have advice for me on what is the most efficient way to repair? And do you expect a soldering iron to have damage like this (I still don't fully believe it!) or is this something else?





? ?

On 10/2/22 5:37 PM, KENT BRITAIN wrote:

If you measure capacitance between the AC cord to the Iron tip, you get about 200 pf.
The AC voltage is capacitively coupled to the Iron tip unless you have a specially grounded IRON,(And have the Ground Connected)
So the average soldering iron is a 200 pf cap plugged into 120 VAC going to your circuit.? Kent

The typical Weller WTCP irons all have grounded tips.

On Sunday, October 2, 2022 at 05:33:28 PM CDT, <linhz0hz@...> wrote:
I am interested if anyone figured this out, because I just fried mine nanoVNA SAA-2N just now. -_-!

I was building some homebrew amplifier. Before measuring that, I wanted to calibrate the test PCB before I put in my transistor. So I would solder different resistors on the board and take measurement. The board is not powered (completely passive).
It was tedious, I got lazy and did not remove my nanoVNA while I solder. I had DC-blocking capacitors though and I got away doing that a few times before so I imagined it would be fine.

But apparently it is not fine this time. Now if I just connect Tx to Rx port, I got high reflection (close to an open) and only -20dB transmission. Software part seems to work still, so I suspect RF front end was killed. I open the casing and took a look, but I don't want to make a rush decision and break it further. Also those EMI shields looks hard to remove.

So does anyone have advice for me on what is the most efficient way to repair? And do you expect a soldering iron to have damage like this (I still don't fully believe it!) or is this something else?

I am interested if anyone figured this out, because I just fried mine nanoVNA SAA-2N just now. -_-!

I was building some homebrew amplifier. Before measuring that, I wanted to calibrate the test PCB before I put in my transistor. So I would solder different resistors on the board and take measurement. The board is not powered (completely passive).
It was tedious, I got lazy and did not remove my nanoVNA while I solder. I had DC-blocking capacitors though and I got away doing that a few times before so I imagined it would be fine.

But apparently it is not fine this time. Now if I just connect Tx to Rx port, I got high reflection (close to an open) and only -20dB transmission. Software part seems to work still, so I suspect RF front end was killed. I open the casing and took a look, but I don't want to make a rush decision and break it further. Also those EMI shields looks hard to remove.

So does anyone have advice for me on what is the most efficient way to repair? And do you expect a soldering iron to have damage like this (I still don't fully believe it!) or is this something else?

Now look what you've done Siegfried. Now I'm going to have to try that.

Greetings,
Also relatively new to H4 and this group. Where does one locate firmware,
release notes and upgrade/downgrade instruction?
Thanks,
Bryan

I run the DiSLord fw as well. I just wish my Saa-2n had an sd card socket.

Hi all, Ive had my H4 a month now and love it. Im not new to VNA's as use a Agilent one at work occasionally.
I still cant believe how so much is packed into a small box for such a brilliant price. Well done to all developers.

My question is , Would it be beneficial to upgrade the firmware? , Plan is to use it with Joel smiths solver software if i can. (would love to see his Labview worksheets, but understand his time and effort into it) labview can be difficult at times, although im used to doing stuff with HPIB with it.

My H4 is as follows :-

version 1.1.01
HW version 4.3 MS

Thanks for letting me join this group, i look forward to any replies and if i can help others i surely will.

Regards Pete