The test doesn’t make sense to me. A nuke typically goes off at 1500 or so feet for maximum wave propagation.
Optimum HOB is the cube root of the yield in kt times the optimum HOB for a 1kt weapon, so a one megaton device would have HOB of 6500 feet, and a 1.7kt would be ~800 feet. A 5 megaton cracker would be 11,000 feet.
They wanted to show the Soviets that we were willing to pop a nuke over our cities to get one of their bombers, or a formation of bombers.
I bet those guys were not fully briefed. Lots of the “volunteers” were not.