HP 8481A Operating And Service Manual page 6

08481-90049
HP 8481A/82 A/83 A
Table 2. Specifications
Note
Wien5 operating in the top 10 dB input power range (e.g. +10 to +20
dBm), an error due to deviation from square law operation may occur.
This possible error, which applies to the 8481A, 8482A, and 8483A, is
expressed as follows:
Worst Case Power Linearity:
+2/-4% (+10 to +20 dBm input range)
Negligible (-30 to +10 dBm input range)