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Model 415E
Section
in
Paragraphs 3-15 to 3-21
Table 3-1. Panel Descriptions
1.
Selects desired 415E power source:BATTERY/
CHARGE position allows internal battery re¬
charge when power cord is connected to AC line,
2.
Indicator lights when power switch is in LINE/
ON or BATTERY/CHARGE position.
3.
Female BNC INPUT connector.
4.
Set input of Model 415E for use with a bolom¬
eter or crystal detector mount. See Paragraph
3-53.
5.
Adjustment allows center frequency variation
by 70 cps.
6.
Attenuator adjusts gain in 10 db steps.
7.
Allows full scale expansion of any 2.0 db portion
of the 10-db scale.
8.
Changes bandwidth from 15 to 130 cps.
9.
Allows initial meter reference setting with a
control range of at least 10-db.
10. Provides fine adjustment of GAIN control meter
settings.
11. Mechanical zero adjustment allows exact sett¬
ing of meter needle to 2.0 db calibration mark.
12. With POWER switch set to BATTERY/TEST, a
meter needle indication within the ''BATTERY
CHARGE" area on the meter face (indicated by
12A) shows that internal battery is charged suf¬
ficiently for proper 415E operation; if needle
indicator is to left (area 12B) of "BATTERY
CHARGED" area, then battery is not charged
sufficiently for proper instrument operation
(option 01 - ONLY).
13. Additional input connector (wired in parallel
with front panel connector); supplied as Option
02 for 415E only upon request.
14. DC output for recorder use (0 to 1 volt into open
circuit or 1000 ohms).
15. AC output for use as tuned amplifier output.
16. Three-conductor AC power cord receptacle
(NEMA-type).
17. Contains power line fuse.
18. Slide switch to allow 115- or 230-volt AC
operation.
3-15. SWR MEASUREMENT EQUIPMENT
AND TECHNIQUES.
3-16. EQUIPMENT.
3-17. A typical setup of equipment used in SWR meas¬
urements is shown in Figure 3-3. The signal source is
usually square-wave modulated at 1000 cps since other
modulating waveforms often cause undesirable fre¬
quency modulation of the source. Harmonics from the
source sometimes cause trouble and can be eliminated
with a low-pass filter.
3-18. The detector should be a square-law device (out¬
put voltage proportional to RF power input) such as a
barretter or a crystal diode operated at low signal
levels. The meter of the 415E is calibrated for square-
law detectors. Crystal diodes are normally more sen¬
sitive than barretters but barretters are square-law
over a wider dynamic range.
Both types of detector
normally maintain accurate square-law response up to
at least full scale deflection with the RANGE-DB switch
set to 30 position and coarse GAIN at maximum. (1 mv
RMS sine wave or 2.2 mv peak-to-peak square wave
causes full scale deflection on HIGH XTAL IMPED
position. On other positions of INPUT switch, 0.15 mv
RMS sine wave or 0.33 mv peak-to-peak square wave
causes full scale deflection.) Above this level these
detectors should be individually checked for departure
from square-law behaviour or manufacturer's data
should be consulted.
02152-3
3-19. A short circuit termination is useful in establish¬
ing reference positions along the transmission line and
is measuring transmission line wavelengths.
3-20. SLOTTED LINE PROBE PENETRATION.
3-21. A general rule in slotted line measurement is to
use minimum probe penetration that still picks up ad¬
equate signal to measure. The probe couples to the
Figure 3-3. Typical SWR Measurement Setup
3-3
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