Richard Clark wrote:
In one case, the measurement "cannot be done," and in another case 6
minutes later it can be done; and the difference all because of one
"particular" coil?

Good Grief! I cannot do the measurement on the W8JI coil
because I don't have the coil. Upon the coil that I do
have, a 75m bugcatcher coil, the measurement was easy.
--
73, Cecil http://www.w5dxp.com