2-4 Keysight 85309B User’s and Service Guide
Operating Information
85309B Front Panel Features
2-
The 85309B and LO source must provide enough power to match the needs of
your specific mixers and to compensate for loss through the LO cable (the
cable that goes from the LO source to the 85309B).
explains how to select the proper amount of power.
LO POWER OUT OF RANGE
When lit, this LED indicates that the LO source is not supplying the amount of
LO power requested by the LO POWER ADJUST control.
The LO POWER OUT OF RANGE circuit compares the LO POWER ADJUST
setting with the voltage coming back from the reference detector. The amount
of expected detector voltage varies depending on the LO POWER ADJUST
setting. Normally the detector voltage is within the expected range, and the
LED is not lit. However, if anything interrupts the ALC loop, or a relatively low
detector voltage is measured, the LED is lit. (The circuit activates the light if
the detector voltage is not within 25% of the expected voltage.) If the LED is lit,
the cause may be one or more of the following:
— The LO source is not set to output a sufficient amount of power. To remedy
this, increase power output (if possible). Make sure your LO source can
generate sufficient power at the maximum LO frequency.
— The LO POWER ADJUST is not set properly on the 85309B. Refer to
6. Adjust the LO Power” on page 7
for instructions.
— The LO source's RF OUTPUT is not connected to the 85309B, or the LO
source is turned off. This can also happen if the LO source is on, but its RF
output is turned off.
— The LO source is not able to supply the requested amount of power in the
measurement frequency range. Make sure your LO source is specified to
produce enough power in the desired frequency range. If the LO cannot
produce enough power at high frequencies, the LO POWER OUT OF RANGE
LED will be lit during the high-frequency portion of the measurement.
During this time LO power will not be correct.
— The reference mixer is not connected to the REFERENCE LO OUTPUT of the
85309B (in other words, the reference mixer is not getting sufficient LO
power).
— The reference mixer's Detector Voltage output is not connected to the
85309B.
— There is a failure of the 85309B's ALC circuitry. An ALC failure will usually
cause the LED to be lit permanently, even though all equipment is
connected properly.
BAND SELECTION (Option 40x Only)
The Band Selection knob on the front panel of the 85309B Option 400/401/402
models allows the user to switch between the low band, high band, and
external selections. The Band Selection switch positions are:
Содержание 85309B LO/IF
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