Model PB-5 | Is the "clamped mode" on the PB-5 a baseline restorer for high rate applications?

No, the clamp simply preserves the amplitude of the pulse when the tail time is long compared to the desired rep rate. This feature is accomplished by clamping the pulse to the baseline before the exponential decay is completed thus allowing the next pulse to start from the baseline rather than some point on the tail. It is recommended that the delay time be set to 3 or 4 us to allow a full recovery to the base line.