Hi, the HPE OfficeConnect 1820 48G Switch correct Product Number is J9981A (not J9981!).
Have a look at HPE OfficeConnect 1820 48G Switch Series QuickSpecs published here, at Page 7 you will find the "Note 1", there you will see supported genuine HPE Transceivers, actually:
- HPE X121 1G SFP LC SX Transceiver (J4858C) <-- that's the one you should use.
- HPE X121 1G SFP LC LX Transceiver (J4859C)
- HPE X111 100M SFP LC FX Transceiver (J9054C)
- HPE X121 1G SFP RJ45 T Transceiver (J8177C)
Keep in mind also that these Transceivers:
- J8177B
- J4858B
- J4859B
- J4860B
- J4860C
- J9142B
- J9143B
are NOT supported by the HPE OfficeConnect 1820 Switch Series (no matter which software version the Switch is running), references here and here.
Be cautious in using non genuine HP Transceivers (declared as "compatible") as the one mentioned (A7446B).