So. I never watched the show in order until recently. Im on the late season 2 episode with the wormhole and I think I was scratching my head before with some other episodes as I thought it was two way. That episode finally made it clear it was one way. Also will add a mildly infuriating but do a community search for stargate does not bring up this community.
All RF. You might be thinking of the scuba suit test run from the 50s
I was thinking more a TOW missile, Hammond of Texas would want to maintain control and not risk radio interference through the gate as much as possible.