Installation guide

Troubleshooting
Block Descriptions for Option 501, 502, 503, 504
1-122
RF Path Block Description for Option 501, 502, 503, 504
Overview
The RF Path for signal generators with Option 501, 502, 503, 504 is made from portions of the following:
• A18 Reference (Option 501, 502, 503, 504)
or A18 Reference (Option 501, 502, 503, 504 with Option 1E5)
• A17 Synthesizer (Option 501, 502, 503, 504)
• A13 Output (Option 501, 502, 503, 504 or Option UNJ)
or A13 Output (Option UNB)
• AT1 Electronic Attenuator (Option 501, 502, 503, 504 or Option UNJ)
or AT1 High Power Mechanical Attenuator (Standard or Option UNJ with Option UNB)
with A28 Reverse Power Protection (Option 501, 502, 503, 504 or Option UNJ)
Frequency generation is performed on the A17 Synthesizer (Option 501, 502, 503, 504) with a
Voltage Controlled Oscillator (VCO). The signal is routed to the A13 Output which contains the
Automatic Level Control (ALC) loop for maintaining leveled power.
When producing RF frequencies below 250 MHz, a heterodyne mixer located on the A13 Output is switched
into the RF path. The RF signal is mixed with a 1 GHz LO, provided by the A18 Reference, to produce the
final 100 kHz to < 250 MHz output; specifications apply to frequencies ≥ 250 kHz.
AM, Pulse, Burst, and I/Q baseband signals modulate the RF on the A13 Output. AM modulation originates
on the A18 Reference, I/Q and Burst modulation originates on the A7 Baseband Generator (Option 001 or
Option 002), and Pulse modulation originates on the A23 Motherboard. AM modulation is routed directly to
the A13 Output, I/Q modulation is routed through the A10 I/Q Multiplexer to the A13 Output, Pulse
modulation and Burst modulation are routed through the A18 Reference to the A13 Output.
The RF signal leaving the A13 Output is then routed through an electronic attenuator. The attenuator
includes a Reverse Power Protection (RPP) circuit to prevent damage to the synthesizer. Options UNB and
Option 506 replace the electronic attenuator with a mechanical attenuator. Option 506 doesn't include an
RPP circuit, but instead includes the A29 DC Blocking Capacitor (Option 506) which helps to protect the
attenuator from dc power that may inadvertently be applied to the RF output connector.
Each signal generator’s maximum frequency and power are dependent on the options that it contains.
A17 Synthesizer (Option 501, 502, 503, 504)
The A17 Synthesizer (Option 501, 502, 503, 504) is part of the Frequency Synthesis Block. It provides the
A13 Output with its input signal. The RF is generated on the A17 Synthesizer (Option 501, 502, 503, 504) by
a VCO and this VCO is either divided or multiplied to achieve a final frequency which is amplified and
filtered prior to it being routed to the A13 Output. A pre-level bias voltage generated by the A13 Output is fed
back where it is used to bias a pin diode and control the amount of RF amplification.