Boost range on RFID reader

I got this RFID reader http://www.seeedstudio.com/depot/125khz-rfid-module-wiegand-p-225.html?cPath=40

But the range for the key tag's are very low (about 1-2cm), any idea on how I could get that a bit up?

1) Tune the coil, add or subtract capacitors to get the coil just o resonance for the frequency it is generating. Get a coil to act as a pickup to see the size of the field you are generating.

2) Wind a bigger coil and tune it as above.

3) Mount it on a none metallic mount as far away from other metals as possible.

Hmm, next problem is then to know when it is tuned right. Got nothing to measure it with.

Got nothing to measure it with.

Then you are stuffed.

Why not measure it with an arduino? Get a pick up coil, through a diode into a capacitor and into the analogue input. Send the readings out to the serial monitor.