HP 8530A, Руководство по эксплуатации и программированию, Страница: 400 / 439

Common Operation Problems
Rotary Joint Problems
Rotary joints must operate at microwave frequencies , and they must physically rotate around
a center axis . Because of this , rotary joints are a common source of problems . All of these
problems cause measurement error and should be corrected immediately . Some common
problems are:
W ow is a uctuation in the test signal level as the antenna positioner rotates . This causes
measurement error at certain antenna positions .
High insertion loss can reduce the LO signal level to the mixers modules . This can increase
the mixers conversion loss , making the measurement system unusable . When the rotary joint
is worn out, it will often have this problem.
Drop outs are caused by the rotary joint having a high insertion loss at certain frequencies or
angular positions . This can cause measurement error only at certain frequencies .
Intermittent rotary joints can cause the test signal to fade randomly . This can cause random
measurement errors .
Noise on the signal is caused by an intermittent rotary joint with very fast intermittent
fading. This can look like noise on the test signal.
Most of the above problems can be solved by cleaning the rotary joint. If the rotary joint
cannot be cleaned, or if cleaning does not solve the problem, replace the rotary joint.
In Case of Diculty 20-5