What was found
UNABLE TO TRANSMIT ON HF1. WE RECEIVED SELCAL ON BOTH HF1 + 2. WE WERE ABLE TO TRANSMIT & COMMUNICATE ON SAT1. GROUNDED - YES. SWAPPED #1 HF TRANSCEIVER AND COMPLETED B737-800 FIM 23-11 TASK 806. HF COMMUNICATION SYSTEM RECEIVE AND TRANSMIT PROBLEM. FAULT ISOLATION AND B737-800 AMM TASK 23-11-00-710-801 HF COMUNICATION SYTEM OPERATIONAL TEST WITH SYSTEM STILL INOP. REINSTALLED ORIGINAL HF TRANSCEIVER. REMOVED AND REPLACED HF1 ANTENNA COUPLER PER AMM 23-11-61-00-801 AND AMM 23-11-61-400-801. OPS CHKS GOOD. ETOPS GROUND VERIFICATION SUCCESSFUL.