Measurements taken from 3325B at 1 MHz: 5370B reference: INT EXT (same 5087A as 3325B uses) Square wave, 2v pk: 15-20 ps 11-12 ps Sine wave, 2v pk: 50-70 ps 30-35 ps Square wave, 1v pk: 20-25 ps 12-13 ps Sine wave, 1v pk: 60-80 ps 40-45 ps Square wave, .1v pk: 40-60 ps 40-45 ps Sine wave, .1v pk: 600-900 ps 500-600 ps -- john, KE5FX