Selection Of Rl - HP 11049A Operating And Service Manual

Model 1l049A
b. Using voltmeter as a monitor, slowly adjust
power supply output to 0.9 volts lor 1l050A
or 2. 85 volts for 1l049A.
c. Conneat voltmeter to thermoelement. Output
should be 6.5 mV ±O. 3 mV.
increase R2; if output is low, decrease R2.
30. An alternative but not as accurate method of
selecting R2 is to assume that the thermoelement
(l
resistunce is 90 and select R2 as 510
[l
and 110 for the 1l050A. If this method is used, the
nominal 7. 5 mV output may be high or low by as much
as 10%.
POWER SUPPL Y
h p72IA
'NPul
7.
Figure
Selection of R2
31. SELECTION OF R1.
32. RI shunts the series combination of the thermo­
element and R2 to adjust the input resistance to 50
Q
±O. 15 and is made up of two approximately equal
resistors connected in parallel.
[2,
about 55 in the Il050A Rl is about 65
POWER SUPPLY
h p"i2IA
If
output is high,
(l
for the 11049A
VOLTMETER
DC h p 419A
0 ,:)
+ -
OuTPuT
1105lA Rl is about 110
should be 1/2 watt, ±5%, metal film resistors.
33. Figure 8 shows a bridge for selecting Rl.
adjusted for null with the drive voltage set so that the
thermoelement operates at near rated full scale input.
Q
Proceed as follows.
a. With the power supply off, construct the
In the 11049A Rl is
Q,
and in the
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0698-5418
200ntO.I'/o
0811-2162
Figure 8.

Selection of Rl

Q,
The resistors used for R1
bridge shown in Figure 8.
Page 8
lhERMO'
El.EMENT
R1 is