Model A5-24 Operation And Service Manual
A5-24 Manual 20 March 2002
Page 7 of 10
Verification of the phase noise levels can be extremely difficult, requiring a cross correlation type
of phase noise test set, with a noise floor below -150dBc at 1Hz and -160dBc at 10 Hz offset.
Procedures
Frequency Response
Connect the tracking source to the input of the Model A5-24, and the spectrum analyser to any
output. Set the tracking generator output level to 10 dBm, and the spectrum analyser to sweep
between 1 MHz and 100 MHz. Adjust the A5-24 gain control (VR1) to give an output level of 13
dBm at 10 MHz.
Measure the frequency response and verify against the specifications.
Harmonic Distortion
Connect the 10 MHz signal source to the Model A5-24 input using the low pass filter to remove
source harmonics to less than -60 dBc. Set the output level to +10 dBm. Connect the spectrum
analyser to any output and adjust the A5-24 gain control to give +13 dBm output. Use the spectrum
analyser to measure the harmonic distortion, and verify against the specifications. Repeat for other
outputs if desired. Take care that the spectrum analyser is not generating harmonics so as to affect
the measurement.
Output to Output Isolation
Set the tracking generator to +10dBm output level, and connect to any output of the A5-24.
Terminate the A5-24 input with a 5
0Ω
load. Connect the spectrum analyser to any other output of
the A5-24, and adjust for maximum sensitivity. Measure the output isolation at 10 MHz and 100
MHz. Note that it may be necessary to fit ferrite sleeves to the spectrum analyser and/or tracking
generator cables to avoid common mode cross talk. The output-to-output isolation is defined as the
tracking generator level minus the level measured by the spectrum analyser.
Repeat for a number of combinations of outputs, choosing adjacent and remote outputs, and verify
against the specifications.
Output to Input Isolation
Connect the tracking generator to any output, and the spectrum analyser to the input of the A5-24
and adjust for maximum sensitivity. Measure the output isolation at 10 MHz and 100 MHz. Note
that it may be necessary to fit ferrite sleeves to the spectrum analyser and/or tracking generator
cables to avoid common mode cross talk. The output-to-input isolation is defined as the tracking
generator level minus the level measured by the spectrum analyser.
Repeat for a number of combinations of outputs, choosing adjacent and remote outputs, and verify
against the specifications..
Maximum Output
Connect the 10 MHz signal source to the input of the A5-24, and the spectrum analyser to any
output. Increase the input level until the third harmonic rises abruptly, showing that clipping is
occurring. Alternatively an oscilloscope may be used to adjust to maximum output. Transfer the
output to the RF power meter and read the maximum output level. Repeat at 10 MHz if required.
Spurious Outputs and Wideband Noise.
With the gain of the A5-24 adjusted for 13 dBm output with 10 dBm input at 10 MHz, disconnect
the signal source and terminate the input with the 5
0Ω
load. Connect the spectrum analyser to any
input and search for discrete spurii. Calculate their level in dBc related to the 13 dBm nominal
output. Measure the wideband noise, using a preamplifier if necessary to improve the spectrum
