[time-nuts] Comparison of HP 5065A optical units

[Matt Huszagh]

Hi,

HP appears to have made some changes to the HP 5065A optical unit over
the course of production. At least, I've noticed two different case
colors: an olive green or maybe dark grey in earlier units, and a silver
case in later units.

Does anyone know what changes were made to the optical unit and any
implications for performance, longevity, etc?

Thanks,
Matt