By the way, I don't think I need to worry about matching the impedance to that of the final application circuit. The story behind this is that a number of test failures are occuring in an attenuator circuit and it is my opinion that the pin-diodes might be the cause. Swapping pin-diodes results in the attenuator circuit performing differently.
The reason for testing the pin diodes was to see if they were in spec with respect to the datasheet. If a spread of results could be obtained, the pin-diodes could then be arranged in batches of similar performance and each type could be subsituted into the final application circuit to see what effect it has on the performance of the attenuator.
The datasheet quotes an on-resistance of 0.6Ohms @100Mhz with a bias current of 10mA, and hence my reason for wanting to test the components with these parameters.
Thanks again Ron,
Brian