开云体育

So, after years of almost constant use (I got nanovna 2 the moment I could) I fried channel 0 because of my stupidity :-( I connected it to an antenna switch that had a short that send +12V DC from relay coil supply right to ch0. Of course this fried the infamous MXD8641 switch chip. The chip is not available from any electronics distributors here in Europe, but I found some on Aliexpress. Unfortunately it'll take months to arrive and I need my nanovna now. So, the official store being out of stock I bought a "black and gold" clone. It arrived in two days. Great.

What is not so great is that I managed to fry the same chip in the new nanovna in less than a day and this time no DC was involved. In fact there was nothing I could think of that could've caused it other than ESD.

So I did, what anyone else would. I butchered my previous nanovna to get the mxD8641 chip from it and I fixed the new one, but now I'm worried. If it broke in a day of use while my old one lasted years. Perhaps new chips have worse ESD protection? As such some sort of input protection should be possible to add. I would much prefer to install some extra parts inside than have to use a dingle etc. So I'm thinking of adding two back to back diodes as protection.

However, why reinvent the wheel. Perhaps someone has already found a good solution for this. If there is one please let me know.

What do you do to protect your nanovna?

For a proper Tektronix spectrum analyzer I have I use a DC block dongle and a pin diode dongle that shorts anything over 10dB to ground. Both are quite bulky.

I still have 3 more chips I can salvage from the old nanovna. I have to make do with them until my purchase comes from China. Please don't suggest I use personal ESD protection as a solution, because I'm working with vacuum tube amplifiers that have 5kV plus voltages. A grounded strap on my wrist, or a grounded mat is the last thing I would want to have around those things.