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?
