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Model 415E
Section V
Paragraphs 5-1 to 5-11
$-1. INTRODUCTION.
5-2.
This section provides instructions for perfor¬
mance testing, calibrating, troubleshooting, and re¬
pairing the SWR Meter.
5-3. PIRF0RMANCI TESTING.
5-4.
PURPOSE.
The procedures listed in Table 5-2
check 415E performance for incoming inspection,
periodic evaluation, calibration, and troubleshooting.
The tests can be performed without access to the in¬
strument interior.
The specifications of Table 1-1
are the performance standards.
5-5.
TEST EQUIPMENT REQUIRED.
The test in¬
struments and accessories required to make the per¬
formance checks are listed in Table 5-1. Test instru¬
ments other than tire ones listed can be used provided
their performance equals or exceeds the Minimum
Required Specifications.
5-6.
ISOLATING ATTENUATOR.
In order to obtain
accurate results when checking the Model 415E, it is
necessary to maintain some attenuation between the
source and the INPUT to compensate for a source im¬
pedance different from the calibrated attenuator used.
The attenuator recommended for test and adjustment
and performance testing has an impedance of 50 ohms.
Therefore, a 5 to 10 db, 50 ohm attenuator is suggested
to be placed between the Oscillator and the attenuators
used in the test setup (Table 5-2). If a separate atten¬
uator is not used, then one of the Model 355 Attenuators
may be left in the setup set to 5 or 10 db, or use an
impedance matching transformer.
5-7. CALIBRATION.
5-8.
GENERAL.
5-9.
The following procedures outline the adjustments
necessary to calibrate the Model 415E.
The actual
adjustments should be made only when it is determined
Table 5-1.
that the instrument is not operating properly. To de¬
termine proper performance, see Table 5-2.
If the
instrument fails to meet any of the given limits or in¬
dications, refer to the troubleshooting paragraph 5-35
for possible causes and corrective action.
This pro¬
cedure is sequential to some extent.
The bias sup¬
plies should beset before any attempt to adjust the am¬
plifier.
Also check the mechanical meter adjustment
before checking any indication on the Model 415E
meter.
Note
To avoid errors due to possible groundloop
currents isolate the Model 415E from ground
used for other measuring instruments. It may
be necessary to use adapters to unground all
instruments except the Model 415E.
5-10.
MECHANICAL METER ADJUSTMENT.
5-11.
When the meter is properly set, the pointer
rests over the calibration (i. e., 2 on the 0 to 2 DB
scale) on the meter scale when the instrument is (1)
at normal operating temperature, (2) in its normal
operating position, and (3) turned off. Set the pointer
as follows to obtain best accuracy and mechanical
stability:
Note
If meter pointer adjustment is changed, EX¬
PAND tracking (Paragraph 5-16) must be
checked and adjusted if necessary.
a.
Turn instrument off.
b.
Rotate mechanical zero-adjustment screw clock¬
wise until meter pointer is to left of 2 (on the 0 to 2
DB scale) and moving to the right toward 2.
c.
Continue to rotate adjustment screw clockwise;
stop when the pointer is exactly on 2.
If the pointer
overshoots 2, repeat steps b and c.
Recommended Test Equipment
Instrument
Type
Minimum Required
Specifications
USE/Check
Recommended
Model
Audio Oscillator
Freq. Range: 400 to 2500 cps
Accuracy: ±3%
Output: 10 volts into 600 ohms
Distortion: less than 1%
All Performance
Tests
hp 200CD
Electronic
Counter
Freq. Range: 400 to 2500 cps
Accuracy: ±1 count ±0. 01%
Frequency, and
Bandwidth
hp 5512A (or
5212A)
AC Voltmeter
Voltage Range: 0. 1 to 1 volt
Accuracy: ±1% of full scale
Freq. Range: 400 to 2500 cps
Input Impedance: 10 megohms
Sensitivity, and
Noise
hp 400H
02152-2
5-1
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