Installation guide

Troubleshooting
Block Descriptions for Option 501, 502, 503, 504
1-126
A10 I/Q Multiplexer (Option 501, 502, 503, 504 or Option UNJ)
or A10 I/Q Multiplexer (Option 506)
The A10 I/Q Multiplexer supplies the Audio 1 (I) and the Audio 2 (Q) signals to the A18 Reference. These
signals are either from the A7 Baseband Generator (Option 001 or Option 002) or supplied externally through
the EXT IQ-IN on the front panel. Once on the A18 Reference, these two signals can be switched to function
as the AM, FM/PM, and PULSE modulating signals. In the wideband-AM mode, the user inputs the
modulation signal through the "I" input on the front panel; this signal is routed through the A10 I/Q
Multiplexer and then to the I/Q Modulator located on the A13 Output. Once there, the "I" input signal can
directly modulate the main RF signal, thus avoiding the bandwidth limitation of the ALC. This method allows
for faster AM rates of dc to 10 MHz (wideband-AM mode) compared to dc to 10 kHz (AM mode).
A7 Baseband Generator (Option 001 or Option 002)
The A7 Baseband Generator (Option 001 or Option 002) supplies the Burst Pulse signal to the A18 Reference.
The Burst Pulse is used to drive the analog pulse modulation circuitry. This signal is not routed through the
multiplexer circuit on the A18 Reference, but goes directly to the pulse drive output-summing node. Here, the
Burst Pulse signal can be summed with the multiplexed pulse drive signals or be used alone to drive the pulse
modulation circuitry located on the A13 Output.
A23 Motherboard
The Internal Modulation Source Function Generator is located on the A23 Motherboard. This circuit uses a
Digital Signal Processor (DSP) chip to create waveforms digitally. This DSP chip uses the 10 MHz reference
standard from the A18 Reference as its main clock. The digital output from the DSP chip is converted
to analog by an output Digital-to-Analog Converter (DAC) and the analog waveform is then directed to the
A18 Reference. The Internal Modulation Source Function Generator produces the following waveforms: Sine,
Triangle, Square, Ramp, Noise, Dual Sine, Swept Sine, Pulse, and dc. The amplitude can be set from 0 volts
up to +5 volts.