HP 436A - Page 77

Adjustments
Model 436A
ADJUSTMENTS
5-22.
POWER
REFERENCE OSCILLATOR
LEVEL
ADJUSTMENT
REFERENCE:
DESCRIPTION:
EQUIPMENT:
Service Sheet
14.
The power reference oscillator
output
is
factory-adjusted to 1
mW±
0.7%
using a special
measurement system accurate
to
0.5% (traceable
to
the
National Bureau
of
Standards)
and allowing for a
0.2%
transfer error.
To
ensure maximum accuracy
in
readjusting the
power reference oscillator,
the
following procedure provides step-by-step instructions
for using specified Hewlett-Packard instruments
of
known capability.
If
equivalent
in-
struments
are used, signal acquisition criteria may vary and reference should be made
to
the
manufacturer's guidelines for operating
the
equipment.
POWER
METER
.....
,.,
"w
lo
@1
"
PO
WEA
REF
OUTPUT
NOTE
The Power Meter
may
be returned
to
the nearest HP
office
to
have the power reference oscillator checked
and/or adjusted.
Refer
to
Section II, PACKAGING.
432A
DIGITAL
VOLTMETER
.---
-,
I
VcoMP
I
L
__
J
THERMISTOR
,...-.,
MOUNT
IVRFI
L_J
-
I I
-
~
~
I I
-
~
Figure
5-7.
Power
Reference
Oscillator
Level
Adjustment
Setup
Power
Meter .
. . . .
Thermistor
Mount
. . .
Digital Voltmeter (DVM) .
HP
432A
HP
478A-H75
HP
3456A
PROCEDURE:
1.
Set
up
the
DVM
to
measure resistance and
connect
the
DVM
between
the
V
RF
con-
nector
on
the
rear panel
of
the
432A and pin 1
on
the
thermistor
mount
end
of
the
432A interconnect cable.
5-10.
2.
Round
off
the
DVM
indication
to
two
decimal places and record this value
as
the
in-
ternal bridge resistance (R)
of
the
432A (approximately
200
ohms).
3. Connect
the
432A
to
the
Power
Meter
as
shown in Figure 5-7.
4. Set
the
Power
Meter LINE switch
to
ON
(in)
and
the
POWER
REF
switch
to
off
(out).
Then wait
thirty
minutes for
the
432A thermistor
mount
to
stabilize before
proceed-
ing
to
the
next
step.
5.
Set
the
432A RANGE switch
to
COARSE ZERO
and
adjust
the
front-panel COARSE
ZERO
control
to
obtain a zero meter indication.
6.
Fine zero
the
432A
on
the
most
sensitive range,
then
set
the
432A
RANGE switch
to
lmW.
•
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