HP 415E User Manual

Model 415Е
3-52. А system error occurs when making meas-
urements on lower 415E ranges due tonoise, For con-
venient reference, a graph (Figure 3-12) is shown to
allow correctionto meter reading forany given meas-
urement. To use this graph, make a signal measure-
ment, then turn RF power source off or disconnect
detector from RF source andnoteaverage meter read-
ing due to noise. Тһе difference between these two
reading is used to obtain the proper correction factor
from Figure 3-12. For example: if the average noise
level is 9.5 db and the measured signal level is 3.5 db
then the difference is 6 db. Refer to Figure 3-12, 6 db
corresponds to an error of 0.1 db. This 0.1 db
correction factor is always added to measured signal.
Hence, 3.5 + 0.1 = 3.6 db (corrected meter reading).
3-53. USE OF CRYSTAL DETECTORS.
3-54. The input impedance of Model415E must always
be higher than the output or source impedance of a
02152-1
Section ПІ
Paragraphs 3-52 to 3-56
bolometer or crystal detector connected to the INPUT
connector (see Paragraph 4-21 for discussion). For low
output impedance devices, such as 100 to 200 ohm
detectors, use 415E XTAL IMPED/LOW switch posi-
tion. For high output impedance devices, such as hp
Models 420B, 423B, 424B, or 786D, use 415E XTAL
IMPED/HIGH position. If improper input impedance is
selected, the crystaldetector may depart from square-
law for which 415E is calibrated. Paragraph 3-55
gives method of checking and calibrating а detector for
square-law response.
3-55. CHECKING SQUARE-LAW RESPONSE.
3-56. Increase the power leveltothe crystal detector
by known increments and note detector response on
415E. Note: a deviation in square-law response may
be due to excessive RF power to the crystal detector
(see Operating literature for specified response
characteristics of crystal detector in use).
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HP 415E Specifications

General

Brand	HP
Model	415E
Category	Measuring Instruments
Language	English