Several calls from Maintenance 004 with a HF check starting at 0017z; 5/2/2022. The stated location was Robbins AFB. After a Mainsail broadcast Maintenance 004 called Mainsail station for a radio check and did not get an answer. I don't believe that I have ever heard Robbins on HF before.
0118 UTC: Another radio check and response from Andrews AFB. "I have you Lima Charlie, this is Maintenance 004 out".