Wow... a blast from the past! If more than one container of those obscure receivers were sold, I would be surprised.
If your considering buying it, Dont!
If you already own it, it may pass through AC3, but unlikely to decode it. Look on the back panel as see if there is a RCA SPDIF or Optical Toslink connector. If so, you mighjt try connecting to a stereo amplifier to test if the AC3 pass through is active.
There are 2 RTV muxes on 137W One is DVB-S2 which that receiver wont get The other is DVB and has the national feeds of TuffTV, MyFamily, RTV, etc and ANY receiver can get them. There is no AC-3 audio (its MPEG2) so even my crappy Viacast 2000 (with its sexy 10 TRANSPONDER entry) can get them and play the audio just fine