HP 8753E - Al4 Fractional-N (Digital)

Node 26
Ext l&f (rear panel external reference input)
Perform step Al2 and then press B &@@~ :Ihl 126) Lxl).
The voltage level of this node indicates whether an external reference timebase
is being used:
n No external reference: about -0.9 V
n With external reference: about -0.6 V.
Node 27
VCXO Tune (40 MHz VCXO tuning voltage)
Perform step Al2 and then press IMeas) :;~~~~~..~~ L27) @ cj)
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&&&& ” - “#g&f&? %
:::: . . . . . . . . . . . :.:..>+% ..__ 2 ._._ - -s:
./ .;...:. T.... ;.s i.... I i ./ ..Y.... :..
This node displays the voltage used to fine tune the Al2 reference VCXO to
40 MHz. You should see a flat line at some voltage level (the actual voltage level
varies from instrument to instrument). Anything other than a flat line indicates
that the VCXO is tuning to different frequencies. Refer to the “Frequency
Accuracy” adjustment procedure.
Node 28
Al2 Gnd 2 (Ground reference)
Al4 Fractional-N (Digital)
lb observe the Al4 analog bus nodes perform step A14, below. Then follow the
node-specific instructions.
Step A14.
Press:
Service Key Menus and Error Messages
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