I have connected an RFID reader to my Arduino Pro Mini. Initially, I had connected a 9V 650 mA adapter to the Arduino raw pin. However, when I connected a 9V 1A adapter, the read range of the RFID reader increased.
Also, could you elaborate please? I'd be happy to provide more details.
Maybe the 650mA supply is a dud?
What I'm taking from this is that you're running the RFID from the ProMini 5V pin?
When you had the ProMini running off a "9V 1A" the RFID did better than when using a "9V 650mA" supply.
Now that I see the data sheet, Page 2 (table 1) informs us that it can run from a wide supply range, 5-15V.
So, why not run it from your "9V" supply directly?
Perhaps you could dispel all doubt and attach or link to a sketch of your hook-up diagram of what you have going?
Or take a good quality picture with everything in shot?