HP 8447A - Page 25

Model 8447A
Operation
SECTION ill
OPERATION
3-1. INTRODUCTION. fuse and turn the instrument back on. If the fuse
blows again, see Section VIII, Maintenance, for
3-2. This section contains the basic information
required to operate the Model 8447A Amplifier or
the Model 8447A -001 Dual Amplifier.
3-3. The Model 8447A and the Model 8447A
-001 provide 20 or 40 dB gain (cascaded amplifi¬
ers) respectively. The amplifier can be used in 50
ohm systems to increase sensitivity, make up for
probe losses, and general amplification of signals
from 0.1 to 400 MHz. The amplifier can also pro¬
vide some amplification of signals up to 700 MHz.
3-4. PANEL FEATURES.
3-5. The Model 8447A and Model 8447 -001
front and rear panel controls and connectors are
explained in Figure 3-1. The descriptions are keyed
to the corresponding items which are indicated on
the figures. Further information regarding the vari-
\ ous uses of the amplifiers are included in Figures
3-2, 3-3 and 3-4.
3-6. OPERATOR CHECKS.
3-7. Five steps should be taken by the operator
to determine the operational condition of either
the Model 8447A Amplifier or the Model 8447A
-001 Dual Amplifier.
a. Turn instrument on, check to see if the
front panel LINE light is on. If the light is on
proceed to step c. If light is off proceed to step b.
b. If the light is off, remove the fuse from
the rear panel. Check to see if the fuse is good. If
the fuse is good proceed to step c. If the fuse is bad
replace the fuse and turn the instrument on. If the
fuse opens again, see Section VIII, Maintenance,
for repair.
c. If the line fuse is good and the power
switch is depressed, connect a known signal (0.1 to
400 MHz) to front panel INPUT. Monitor the
OUTPUT jack to see that the Model 8447A pro¬
vides approximately 20 dB gain to the input signal.
If there is no gain, go to step d.
d. If the rear panel fuse is OK, turn the in¬
strument top side down and remove the bottom
cover. Check to see that the fuse on the A1 Power
Supply board is good. If the fuse is bad, replace the
repair.
e. I f the Model 8447A provides the proper
gain and the front panel light is out, replace the
lamp (see paragraph 3-10, Operator Maintenance).
NOTE
Be sure to provide 50f2 source and load
impedances.
3-8. OPERATING INSTRUCTIONS.
3-9. Figure 3-2 thru 3-4 contain general applica¬
tion information for the Model 8447A and the
Model 8447 -001 Dual Amplifiers.
3-10. OPERATOR MAINTENANCE.
3-11. Operator maintenance is limited to replace¬
ment of the front panel LINE switch light, the A1
power supply fuse, and the rear panel fuse. For any
internal maintenance on the amplifiers, see Section
VII, Maintenance.
3-12. FUSES.
3-13. To replace the rear panel fuse (FI), remove
the rear panel fuse knob and replace the fuse with
0.5 amp 250 V fuse.
3-14. To replace the A1 Power Supply (A1F1)
fuse, turn the instrument on its top. Lift tilt stand
and remove the bottom cover. Replace the fuse on
the A1 Power Supply board with 0.5 amp 250 V
fuse.
3-15. LAMP REPLACEMENT.
3-16. To replace the front panel line switch lamp
(DS1), proceed as follows:
a. Disconnect cord from rear panel recep¬
tacle.
b. Pull the white cover portion of this switch
from the instrument and then remove the lamp
from inside the cover.
c. Replace old lamp with a new lamp (see
Section VI for part number of DS1).
d. Place white cover into switch receptacle.
e. Align tab on white cover with socket and
push in.
3-1