|I would take it back and return it too. The same cable should test the same time after time.........regardless of how good your tester is or is not.|
From the sounds of it, you don't have to make enough cables to really require the use of a tester. If it makes you feel better to have one, by all means, go for it. The price is low so it's not a big loss purchasing the unit you want.
But to be completely honest, as long as you double check to ensure you have the wires in the correct slots in the RJ-45 end, that the wires go to the very end of the slot and that the cable casing is in the crimp, then you can be pretty sure your cable will work just fine without a tester. I test/certify everything I make at work, but I've never bothered at home. Once I plug it in if the NIC shows its connecting at 1000 Mbps and it works, then I know I made it right.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.