As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HF NR 1 RADIO FAILED IN FLIGHT. WHEN TRYING TO TUNE ANY FREQUENCY, THE TUNING TONE CONTINUED UNUSUALLY ON (10+ SEC) WHEN NORMALLY IT'S JUST A FEW SECONDS. AFTER THE TONE STOPPED, NEITHER CAPT OR F/O COULD TRANSMIT ON HF 1. WHEN WE REQUESTED A SELCAL CHECK, THE SELCAL LIGHTS ILLUMINATED ON BOTH HF 1 & 2. DATA MODE WORKS. GROUNDED-YES. REMOVED & REPLACED HF NR 1 TRANSCEIVER, PER B737-900 AMM 23-11-21. OPERATIONS CHECK GOOD. NO DEFECTS NOTED AT THIS TIME. MX ACTION REVERSED. PLACARD REMOVED.