I have recently purchased 10xSIM800l modems for use in a Arduino project. When I test the units using the correct voltage, 4.0v, and with 3A PSU and a SIM with external antenna I find that only 6 out of the 10 actually connect to a GSM network. eg quick flashing LED changes to slow flashing LED.
Can I assume that its down to poor manufacturing or would I need to send AT commands to turn the RF side ON? If it is poor manufacturing is their anything I can do to rectify the problem?
Thanks in adavnce
Danny