As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO TRANSMIT ON HF #2 RADIO. NO SIDE TONE. RECEIVES FINE. GROUNDED - YES. UNABLE TO DUPLICATE OPS NORMAL. REF B737-800 AMM 23-11-00. DUE TO HISTORY AND TECH SVCS NOTE, REQUIRES PRECAUTIONARY REPLACEMENT OF #2 COUPLER. REMOVED AND REPLACED #2 HF COUPLER AND #2HF TUNES/OPS CKS NML PER B737-800 AMM 23-11-61.