HP 8753E - A13;A14 Fractional-N Check; Fractional-N Check with Analog Bus

L HB and L LB Lines. These complementary signals toggle when the instrument
switches from low band to high band as illustrated by Figure 7-16.
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Figure 7-16. Complementary L J3.B and L LB Signals (Preset)
If all of the digital signals appeared good, the Al2 assembly is faulty
A13/A14 Fractional-N Check
Use the analog bus or an oscilloscope to check the Al4 VCO’s ability to sweep
from 30 MHz to 60 MHz. The faster analog bus method should suffice unless
problems are detected.
Fractional-N Check with Analog Bus
..-.- .._............................ - .._ -__
_ _ .,.~.....~.,..... _ _ i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ../~_.......
. . . . . . . . . . .,.
.,.,...,.......,.,.. :,. ,. ,.
/,.,.,._ ;; _.
;&&&+z&
. . . . . . . . . . . . . . . . . / _ .;,..
_ _
.i
-~,~,~~~~~~~ ~~~~ to sMtch on the andog bus md the
..:... :<:<x i........................................~...........
-..- - .._.. -
fractional-N counter.
.,.,.,...,.,.,.,.,.,.,.,.,.,.....,......_ . . . i :..:
:,:,.,. _
2. Then press Ihnenu_) ~~~~~. to set the analyzer to CW mode.
._..._..................... ..::.-::::.
3. Set the instrument as indicated in ‘lhble 7-5 and see whether the VCO
generates the frequencies listed.
7-24 Source Troubleshootin(l