Use the right impedance terminator.
If you see used BNC terminators at a hamfest, purple cap is 75-ohm, green cap is 50-ohm.
Depending on the critical nature of the circuit, you can make them. Use 1% metal oxide resistors.
Amazon has them, as does Ebay, and Aliexpress.
Optionally, call a TV station and ask someone at the TV station if you can buy some for $1 each. (not too many digital systems use terminators anymore. We ended up with a 2 gallon bucket of them, post transition.)