Trying to use Arduino to output basic square wave through coaxial cable

NOTE: I made a similar topic months ago asking for HOW to do this. Now I HAVE done it, and it stopped working. So I'm hoping someone with experience in electronics can take a look and debug what possibly caused my effective solution to stop working.

For my project, I need to output a square wave (with pulses that vary in frequency) through a coaxial cable so that I can feed it into a specialized port on my computer for a specific software.

The square wave is simple. Essentially, I have:

digitalWrite(10,HIGH) delay(1000) digitalWrite(10,LOW) delay(1000) digitalWrite(10,HIGH) delay(2000) digitalWrite(10,LOW) delay(2000) digitalWrite(10,HIGH) delay(3000) digitalWrite(10,LOW) delay(3000)

I have a wire going from pin 10 on my Arduino to a breadboard. I also have a coaxial cable that I cut in half, and I soldered 1 jumper wire to the inner copper cable, and soldered another jumper wire to the silver wire on the outside of the copper cable. So I plug the coaxial copper cable/jumper wire into my breadboard right next to the wire that is getting the signal from pin 10. I plug the coaxial silver cable/jumper wire into GND. Then the other end of the coaxial cable that is still intact screws into my computer so I can read the signal as a data stream in one of my data recording softwares.

I honestly don't even know why I soldered the wires in that way since I'm really new to this and don't know much about coaxial cables. But it worked. My software which is only reading the signal coming in through the coaxial cable, was able to detect the proper square wave.

This was about two weeks ago. Now I tried the same thing again, and suddenly my software is not able to detect the square wave. So I rearranged my code a little bit to see what was going on.

So Pin 10 is outputting the square wave into the breadboard, and then right next to that on the breadboard I have another wire feeding that same signal back into my Arduino to be read at Pin 7. Then I changed my code to read Pin 7 into Serial.

What I've noticed is that when the jumper wires from the coaxial cable are NOT plugged into the breadboard, the Serial Monitor is able to perfectly read the Square Wave at Pin 7. When I plug the coaxial cable jumper wires back into the breadboard (so it's right next to the wires of Pin 7/Pin 10), suddenly the signal being read at Pin 7 disappears. Serial is still able to read it with the proper delays, but it is unable to read a "HIGH" voltage. (So it's basically 0, delay 1 second, 0 delay 1 second, 0 delay 2 seconds, 0 delay 2 seconds when it SHOULD be: 1, delay 1 second, 0 delay 1 second, 1 delay 2 seconds, 0 delay 2 seconds).

I'm assuming there is an issue with the way I soldered the jumper wires to the coaxial cable, but I'm wondering whether any of you can confirm that for me or provide additional insight into what the problem is. If the problem is with the way I soldered my wires to the coaxial cable, what would be an easy/effective way to get this done? Should I just get a new coaxial cable and try to connect the wires in the same manner but simply try to get a better solder connection?

Thanks!

Post a photo of the circuit and a photo of a hand drawn schematic of the circuit.

Sounds like time to investigate with a multi-meter. Check and make sure that 5v signal is getting to the coax , then to the other end. Check continuity, make sure you have connections where you want them, also check that you don't have shorts where you don't want them. We could make a lot of guesses but if the circuit had worked before I would investigate before making too many changes.

A multimeter and some patience is probably all you need. How long is the coax?

Have you remembers to use the pinMode call to make your outputs into outputs?