callsign Sentry-6 calling any MARS for radio check on 11175khz USB (AE11E6) (E3TF) #HFGCS August 11, 2020 Aleph HFGCS Tweets callsign Sentry-6 calling any MARS for radio check on 11175khz USB (AE11E6) (E3TF) #HFGCS