14 Keysight Agile Signal Generator Service Guide
Troubleshooting
A18 Lowband Output Module
A18 Lowband Output Module is responsible for accepting Lowband and a
portion of Midband signals, and adjusting these to the appropriate power level
for frequencies between .01 to 3 GHz. This is achieved by passing the signals
through a series of amplifiers, attenuators, and filters before passing the signal
on to the output stage. A portion of the Lowband signal is coupled off for ALC
control via a Lowband detector, or through a parallel path called the
"< 40 MHz" path. The latter path uses an ADC on the RF Deck Board for signals
below 40 MHz.
For frequencies between 0.01 to 1.43 GHz, the input signal comes from A14
Lowband/Highband Switch. For frequencies
> 1.43 GHz to 3.0 GHz, the input
signal comes from A17 Agile Mod/Filter. For frequencies between .01 to 3 GHz,
the A18 Low Band Output Module provides pulse modulation circuitry, and
filtering. The output is routed to the A17 Agile Mod/Filter output. The output of
the coupler detector is routed to A15 ADC (Analog Digital Convert) section for
output leveling control during ALC on
A19 40 GHz Doubler (Option 540/54E)
The A19 40 GHz Doubler generates frequencies from 20 to 40 GHz. The
doubler has two inputs from the A17 Agile Modulation Filter. One input routes
frequencies ≤ 20 GHz to a bypass switch, and the other input routes 10 to
20 GHz signals to the 40 GHz Doubler. After doubling, band pass filters
eliminate unwanted harmonics. The output is routed to the A20 Output
Leveling Module.
A20 Output Leveling Module
The main function of A20 is to provide a feedback signal for Automatic Leveling
Control. The A20 Output Leveling Module contains two major components, a
coupler and a detector. The coupler couples off a portion of the RF signal
which is then detected and used to monitor the RF output power level. The
detector converts the coupled RF signal to a DC voltage that is routed to the
A15 RF Deck Interface where it is used during ALC on. For Option AT1/AT2, an
electronic attenuator, a mechanical attenuator, and a transfer switch are
added to the coupler output. The RF path and ALC calibration data are stored
in the detector's bias board
RF Output Connector
On 20 GHz instruments, the RF output connector is an APC 3.5 male or Type-N
(Option 1ED). On 40 GHz instruments, the RF output connector is a 2.4 mm
male. Option 1EM moves all front panel connectors to the rear panel.
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