Protek A434L Operating Manual page 62

Depending on the choice of an amplitude unit, allowable input value is
limited to the following:
 In case Y scale is VSWR:
Max(Top): Setting value can be from 1.01 to 65.00 and it

cannot be equal to or smaller than the Min(Bottom) setting
value. Adjustment can be made by steps of 0.01.
 Min(Bottom): Setting value can be from 1.0 to 64.99 and it
cannot be equal to or larger than the Max(Top) setting value.
Adjustment can be made by steps of 0.01.
In case Y Scale is Return Loss:

Max(Top): Setting value can be from 0.0 to 59.99dB and it

cannot be equal to or smaller than the Min(Bottom) setting
value. Adjustment can be made by steps of 0.01.
Min(Bottom): Setting value can be from 0.01 to 60.00dB and

it cannot be equal to or larger than the Max(Top) setting
value. Adjustment can be made by steps of 0.01.
 Limit line: Turns On and Off the display of the limit line on the
screen.
If a measurement exceeds the limit line, the trace above the

limit line is displayed in red color.
 An audible beep sound is generated.
 Limit level: Sets the position of a limit line. Depending on the Y-
scale of a graph, the input value is set automatically as none for
VSWR or dB for Return Loss. The value of limit level is displayed on
the limit line.
The instrument takes the negative value of the Return Loss
internally. Users don't need to add minus (-) sign before typing
in a value. Y-axis of a graph also doesn't show minus sign.
62