HP 8340B Manual page 291

5-15.
ALC ADJUSTMENTS (Cont'd)
Table 5-7. Selected Values of Low Band Temperature
Compensation Resistors in
A25
BVL
(Ohms)
800-870
870-950
950-1050
1050-1160
1160-1270
1270-1380
1380-1490
1490-1600
A25R109(Ohms)
3830
3480
3160
2870
2370
2150
1960
1620
A25R115(Ohms)
9090
8250
7500
6810
6190
5620
5110
4640
ALC ADJUSTMENTS
Description
The ALC detectors
have a
linear region. Below the linear region the detector response is
non-linear.
The ALC
circuit
attempts
to compensate for the non-linear regions such that the overall response of
the
ALC
loop
is
linear
over a
40 dB range
from —20 dBm to
+20
dBm. Since there is
a
separate
detector
and modulator for the high bands (Bands
1
-
4) and low band (Band
0), there are separate
adjustments for the high bands and low band.
The DUT is
set
to
a
CW
frequency
within the band
to be
adjusted.
The
RF attenuator and ALC
is set for
de-coupled operation
(controlled separately).
The RF
output level is set using the
ENTRY
keys. The
power
is measured with
a
power meter and
if
necessary adjustments are made until the
power meter
indication
is correct at each
DUT power
level.
Equipment
Power Meter
............................
Power Sensor
...........................
Digital Voltmeter
(DVM)
....................
Power Supply
...........................
Adapters
APC 3.5 (f) To Type
N
(m) (8341
B
only)
.....
HP P/N 1250-1744
,
HP P/N 5061-5311
APC 3.5 (f) To APC 3.5 (f) (8340B
only)
.....
NOTE
The ALC circuit contains several adjustment controls
and the
adjustment includes changing calibration constants stored in
memory.
All
of the adjustments
in
each band interact with each
other.
In
addition,
the high band
0
dBm adjustment affects the low band,
and the high
bands
+18
dBm adjustment affects the low
band.
Before making any
adjustments, check the operation of the ALC
circuit as described below
and make adjustments
only
if
necessary.
NOTE
In the following procedures, do not put P.C. boards on extender boards.
.
HP 436A
HP 8485A
HP 3456A
HP 6294A
Adjustments
HP 8340B/41B