A8 Floating Bnc Bypass (N5173B/83B) - Keysight N5171B EXG Service Manual

Troubleshooting
Overall Block Description
is then opened, pulse modulation turned on, and the integrator output is
maintained at the closed loop level. Since there is no feedback in open loop
operation, power can drift over time and with temperature changes.
In power search auto mode, when changes are made in frequency or power, a
new search is executed.
If ALC is on during pulse operation, pulse amplitude is maintained by the ALC
loop. (See the N5173B or N5183B Data Sheets for pulse width restrictions.)
Attenuator Option 1E1
The ALC circuit controls power across a finite power range. The Option 1E1
mechanical attenuator, added to the RF path after the coupler/detector,
enables the ALC to maintain leveled power over an extend power range. The
signal generator performs a separate calibration to remove losses associated
with the attenuator, RF connector, and cables. Without Option 1E1, the RF
signal passes through the attenuator which is set for zero dB.
Generating Frequencies > 3.2 GHz
The A3 RF assembly provides a signal to the A7 Micro Deck's 20 GHz doubler
at a frequency range of 2.5 GHz to 5 GHz. Depending on the desired output
frequencies, the 20 GHz doubler will either pass through the > 3.2 GHz to
5 GHz frequency, double the 2.5 GHz to 5 GHz frequency (for frequencies from
5 GHz to 10 GHz), or double the 5 GHz to 10 GHz frequency (for frequencies
from 10 GHz to 20 GHz). Instruments with Option 532 or 540 have a 40 GHz
doubler that doubles the 10 GHz to 20 GHz signals.
Pulse Modulation
Pulse modulation drive for all frequencies is developed on the A3 RF assembly.
For frequencies > 3.2 GHz, the pulse modulator diode is in the Mod Filter on
the A7 Micro Deck.
Amplitude Modulation
The AM drive signal is generated on the A3 RF assembly, routed to the ALC
assembly on the A7 Micro Deck, and then applied to the ALC modulation diode
in the Mod Filter on the A7 Micro Deck.

A8 Floating BNC Bypass (N5173B/83B)

The A8 Floating BNC Bypass isolation circuit is a filter that minimizes
interference caused when external equipment is connected to the external ALC
Input BNC. The circuit isolates DC voltage and high frequency signal
components that might be present between different grounding paths.
Keysight X-Series Signal Generators Service Guide 23