Electronics, Ham Radio

The CAT is back

The CAT is back

Around a year ago, my chinese CAT cable stopped working.
I took my oscilloscope out of the box and tried to find where the problem is.
I came to conclusion that the USB to serial chip (Prolific or other crap) is bad and produce only 1v.

Where’s the problem?

I had FTDI FT232 board in my drawer and I tried it to see if my theory is correct.
As I thought, it worked perfectly.

I then decided to make my own board based on the FTDI FT232 chip, because I wanted a small board and all the boards on eBay or Sparkfun was big and included many useless connections.

The old chinese board


After creating the scheme and designing a nice board, I had an issue with the drillings for the USB type A and I had to give up on my beautiful board.

Half way DIY

Few weeks ago, someone sent me this board:
Which hosts everything I need in a small factor.

Well, not everything.
After ordering 3 PCBs, I noticed it has Mini USB 🙁
So I ordered Mini USB connectors, FT232RL and few capacitors and started the journey.

PCB #1

At the beginning I soldered everything and connected to my PC just to find sparks coming out of the USB connector.
Apparently, the 5V pin on the USB connector was short to ground.
I tried to desolder the USB but I couldn’t because the FT232 was on the way.
When I tried to desolder the chip, I ripped off few pads and broke one leg.
First PCB is dead.

PCB #2

The new chip didn’t work (probably burned because a mistake) and the PC didn’t show any new device.

PCB #3 – Last chance

After getting 2 more FT232RL (this time original and not from eBay), I carefully soldered everything together and connected to the PC.

BOOM, it worked.
Or at least it’s recognized.

The last board…

More debugging

When I connected the wires from the old USB to serial board I tried to open a software and control my Yaesu FT857 and it didn’t work.
My oscilloscope came to the rescue again and I found a broken wire connection.
After fixing the wire it all worked again and I could control my Yaesu as before.


Can’t finish without a nice case printed on my 3D printer, designed in Fusion360.

Render of the case


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