An oscilloscope probe test fixture provides separate clamps for pressing each probe tip against a location along a transmission line. Multiple adjacent clamps may share a common axle. One clamp is positioned over a ground plane that adjoins the center conductor of a strip transmission line, while another is positioned over that center conductor. Each individual clamp has a respective compression spring on one side of the axle to produce clamping on the other, and the lengths from the axle to the springs act as a respective thumb lever that allows each clamp to be opened to receive a probe tip. The length from the axle to the spring is significantly longer than that from the axle to the actual clamping surface (foot) to provide increased clamping force. The foot of each clamp is mostly under the axle, while their thumb lever portions extend parallel to a substrate that carries the strip transmission line, allowing the location of the clamping to be close to the driven end of the test fixture. The transmission line may be internally terminated or terminated externally through an RF connector.