Model
A5
-12 Operation & Service Manual
A5-12 Manual A5 21 January 2005
Page 10
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.
4.2.4
Output to Input Isolation
Connect the tracking generator to any output, and the spectrum analyser to the
input of the A5-12 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..
4.2.5
Maximum Output
Connect the 10 MHz signal source to the input of the A5-12, 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.
4.2.6
Spurious Outputs and Wideband Noise.
With the gain of the A5-12 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
analysers’ noise figure, correct for measurement bandwidth, log amplifier, and
detector. Alternatively use a noise figure meter.
4.2.7
Input and Output SWR
Measure using a reflection bridge or network analyser
4.2.8
Setting Up
The only user adjustment required is to set the output levels. To do this proceed as
follows:
