Difference in chips?

[THLL]

Hello I have noticed that some of the chips do not work like the others.

What is the difference between a NRF24L01+ 1420JB and NRF24L01+ 1405FJ

[Asbjørn]

We have seen several users here lately that have bought modules with counterfeit nRF24L01+ on them. They report that especially the Auto-ACK functionality is not working on the fake ones. May I ask you from where you got the various chips that you have and what kind of behavior you are seeing that's not according to your expectations?

[Asbjørn]

I would recommend you to use for example digikey.com, sparkfun.com, www.semiconductorstore.com/ or contact our distributor directly.