Wiltron 59A50 User manual

OPERATION AND MAINTENANCE MANUAL
FOR SWR AUTOTESTERS AND BRIDGES
1. INTRODUCTION
This manual provides product descriptions and
specifications for WILTRON Series 59, 63, and 97
SWR Autotesters and Series 58, 60, 62, and 87 SWR
Bridges. It also includes procedures for measuring
the directivity of these components.
2. GENERAL DESCRIPTION
The SWR Autotesters and bridges (Figure 1) are
broadband microwave measurement instruments.
They are used with other test instruments for mak-
ing fixed-- and swept--frequency return loss (SWR)
measurements over a wide range of radio frequen-
cies. Return loss measurements are made to check
the performance of systems, subsystems, and micro-
wave components such as amplifiers, directional
couplers, attenuators, filters, splitters, and termina-
tions.
The WILTRON SWR Autotesters and bridges are
precision--balanced Wheatstone bridges. Except for
the two 4--port comparison--type instruments (Mod-
els 59A50 and 58A50) that use an offset termination
in the reference arm, every model has an internal
precision reference termination included in one arm
of its bridge. The major difference between the SWR
Autotester and the SWR bridge is that the SWR Au-
totester contains a built--in RF detector.
3. PERFORMANCE SPECIFICATIONS
Performance specifications for SWR Autotesters are
listed in Table 1; specifications for SWR bridges are
listed in Table 2.
490 JARVIS DRIVE l MORGAN HILL, CA 95037-2809 P/N: 10100-00008
REVISION : M
PRINTED: NOVEMBER 1994
COPYRIGHT 1983 WILTRON CO.
Figure 1. Typical WILTRON SWR Autotester and SWR Bridge

Models Directivity
(dB) Accuracy➀Input Z (ohms) Test Port Connector Physical
59 Series Comparison SWR Autotester , 10 MHz to 18 GHz
59A50 36
0.01–8 GHz: 0.016 ±0.06ρ2 ➁➂
8–18 GHz: 0.016 ±0.1ρ250 GPC–7
Dimensions:
7.6 x 5.1 x 2.8 cm
(3 x 2 x 1 1⁄8in.)
plus connectors
Weight:
340 g (12 oz)
63 Series SWR Autotesters, 10 MHz to 4 GHz
63A50
40➃0.01 ±0.06ρ250
GPC7
Dimensions:
6.7 x 5.1 x 2.54 cm
(2 5⁄8x 2 x 1 in.)
plus connectors
Weight:
340 g (12 oz)
63N50 Type N Male
63NF50 Type N Female
97 Series SWR Autotesters , 10 MHz to 18GHz
0.01–8 GHz 8–18 GHz
50
GPC–7
97A50 36 0.016 ±0.06ρ20.016 ±0.1ρ2
Dimensions:
7.6 x 5.1 x 2.8 cm
(3 x 2 x 1 1⁄8in.)
plus connectors
Weight:
340 g (12 oz)
97A50-1 40 0.01 ±0.06ρ20.01 ±0.1ρ2
97S50 35 0.018 ±0.08ρ20.018 ±0.12ρ2WSMA Male
97SF50 WSMA Female
97S50-1 38 0.013 ±0.08ρ20.013 ±0.12ρ2WSMA Male
97SF50-1 WSMA Female
97N50 35 0.018 ±0.08ρ20.018 ±0.12ρ2Type N Male
97NF50 Type N Female
97N50-1 38 0.013 ±0.08ρ20.013 ±0.12ρ2Type N Male
97NF50-1 Type N Female
All Models
Insertion Loss (from input to test port): 6.5 dB nominal
Detector Output Polarity: Negative
Output Time Constant: 2 µs
Maximum Power Input: 0.5 watts (+27 dBm)
Input Connector: Type N Female
Detector Output Connector: BNC Female
➀Where ρis the reflection coefficient being measured. Accuracy includes the effects of test port reflections and directivity.
➁When used with 28A50-1 Precision Termination. The effective directivity of the SWR Autotester can be increased to 60 dB by using the
Ripple Extraction return loss measurement technique with the 18A50 Air Line and 29A50-20 Offset Termination.
➂See paragraph 4 for explanation of accuracy and other terms.
➃46 dB directivity available as Option 1. Option 1 accuracy: 0.005 ±0.06ρ2.
Table 1. SWR Autotester Performance Specifications
2SWR OMM

Models Directivity
(dB) Accuracy➀Input Z
(ohms) Test Port Connector Physical
58 Series Comparison SWR Bridge , 2 to 18 GHz
58A50 35
2–3 GHz: 0.018 ±0.32ρ2 ➁ ➂
3–4 GHz: 0.018 ±0.2ρ2
4–18 GHz: 0.018 ±0.13ρ250 GPC–7
Dimensions:
6.7 x 5.1 x 2.2 cm
(2 5⁄8x 2 x 7⁄8in.) plus connectors
Weight:
340 g (12 Oz)
60 Series SWR Bridges, 5 MHz to 2 GHz
60A50
40➃0.01 ±0.09ρ250
GPC–7
Dimensions:
6.7 x 5.1 x 2.54 cm
(2 5⁄8x 2 x 1 in.) plus connectors
Weight:
340 g (12 oz)
60N50 Type N Male
60NF50 Type N Female
62 Series SWR Bridges, 10 MHz to 1GHz
62N75➄
40 0.01 ±0.12ρ2
75 Type N Male Dimensions:
6.7 x 5.1 x 2.54 cm
(2 5⁄8x 2 x 1 in.) plus connectors
Weight:
170 g (6 Oz)
62NF75 75 Type N Female
62B75 75 BNC Male
62BF75 75 BNC Female
87 Series SWR Bridges, 2 to 18 GHz
87A50 35
2–3 GHz: 0.018 ±0.32ρ2
3–4 GHz: 0.018 ±0.2ρ2
4–18 GHz: 0.018 ±0.13ρ250 GPC–7
Dimensions:
7.3 x 5.1 x 2.86 cm
(2 5⁄8x 2 x 1 1⁄8in.) plus connectors
Weight:
340 g (12 Oz)
87A50-1 38
2–3 GHz: 0.013 ±0.32ρ2
3–4 GHz: 0.013 ±0.2ρ2
4–18 GHz: 0.013 ±0.13ρ2
All Models
Insertion Loss (from input to test port): 6.5 dB nominal
Maximum Power Input: 0.5 watts (+27 dBm)
Input Connector: Type N Female, stainless steel, except 67B and 67F Series that have BNC Female
➀Where ρ is the reflection coefficient being measured. Accuracy includes the effects of test port reflections and directivity.
➁When used with 28A50-1 Precision Termination. The effective directivity of the bridge can be increased to 60 dB by using the Ripple
Extraction return loss measurement technique with the 18A50 Air Line and 29A50-20 Offset Termination.
➂See paragraph 4 for explanation of accuracy and other terms.
➃46 dB directivity available as Option 1. Option 1 accuracy: 0.005 ±0.09ρ2.
➄75ΩType N Female connectors will withstand occasional mating with 50Ωconnectors without damage.
Table 2. SWR Bridge Performance Specifications
SWR OMM 3

4. EXPLANATION OF SWR
AUTOTESTER AND BRIDGE
SPECIFICATIONS
Certain key specification terms are explained below.
a. Accuracy. This three-element term defines
the accuracy with which an SWR Autotester or
bridge can make a reflected signal measure-
ment. The three elements (0.01 ±0.06 ρ2) are
described below.
1st Element: (0.01) is the directivity of the SWR
Autotester or bridge expressed as a reflection
coefficient (40 dB for this example, see Table 6).
2nd and 3rd Elements: ±0.06ρ2is the deprecia-
tion in accuracy due to test port mismatch (im-
pedance discontinuity). Element 2 (0.06) is the
inherent test port mismatch expressed as a re-
flection coefficient. The 3rd element, rho (ρ), is
the reflection coefficient of the device under test
(DUT). The entire expression describes the
measurement uncertainty caused by the re-
flected signal being re-reflected by the test port
mismatch.
b. Directivity. A figure of merit expressed in dB.
This figure represents the ratio of the power
levels as seen at the output port when (1) the
test port signal is fully reflected, and (2) the test
port is perfectly terminated.
c. Frequency Sensitivity. The maximum varia-
tion in output power/voltage that can be ex-
pected due to a change in frequency over the
specified range when the input power is held
constant
d. Output Time Constant. The amount of time
required for the selected output pulse to either
rise from the 10% to the 90% point or fall from
the 90% to the 10% point on the waveform.
5. PRECAUTIONS
The SWR Autotesters and bridges are high-quality,
precision laboratory instruments and should receive
the same care and respect afforded such instru-
ments. Complying with the following precautions
will guarantee longer component life and less equip-
ment downtime due to connector failure. Also, such
compliance will ensure that SWR Autotester or
bridge failures are not due to misuse or abuse—two
failure modes not covered under the WILTRON war-
ranty.
a. Beware of Destructive Pin Depth on Mating
Connectors. Before mating, measure the pin
depth (Figure 2) of the device that will mate with
the SWR Autotester or bridge, using a WILTRON
Pin Depth Gauge (Figure 3) or equivalent. Based
on SWR Autotesters and bridges returned for
repair, destructive pin depth of mating connec-
tors is the major cause of failure in the field. (A
destructive pin depth has a center pin that is too
long in respect to the connector’s reference
plane.) When the SWR Autotester or bridge is
mated with a connector having a destructive pin
depth, damage will likely occur to the SWR
Autotester or bridge.
The center pin of SWR Autotester or bridge con-
nectors has a precision tolerance measured in
mils (1/1000 inch). Connectors on test devices
that mate with SWR Autotesters and bridges
may not be precision types and may not have the
proper depth. They must be measured before
mating to ensure suitability. When gauging pin
REFERENCE
PLANE
MALE
PIN
DEPTH
(INCHES)
REFERENCE
PLANE
FEMALE
PIN
DEPTH
(INCHES)
Figure 2. N Connector Pin Depth Definition
0
1
2
3
45
1
2
3
4
211 2
Figure 3. Pin Depth Gauge
4SWR OMM

depth, if the SWR Autotester or bridge connector
measures out of tolerance (Table 3) in the “+”
region of the gauge (Figure 3), the center pin is
too long. Mating under this condition will likely
damage the SWR Autotester or bridge connector.
On the other hand, if the test device connector
measures out of tolerance in the “–” region, the
center pin is too short. While this will not cause
any damage, it will result in a poor connection
and a consequent degradation in performance.
b. Avoid Over Torquing Connectors. Over
torquing connectors is destructive; it may dam-
age the connector center pin. Finger-tight is usu-
ally sufficient, especially on Type N connectors.
Should it be necessary to use a wrench to tighten
SMA or WSMA connectors, use a torque wrench
that breaks at 5 inch-pounds. As a general rule,
never use pliers to tighten connectors.
c. Do Not Disturb Teflon Tuning Washers On
Connector Center Pins. The center conduc-
tor on many SWR Autotester or bridge connec-
tors contains a small teflon tuning washer lo-
cated near the point of mating (interface) (Figure
4). This washer compensates for minor imped-
ance discontinuities at the interface. The
washer’s location is critical to the SWR
Autotester or bridge’s performance. Do not dis-
turb it.
Series Port/
Conn. Type Pin Depth (MILS) Gauge Reading
58, 59,
87,
971
INPUT – NF 207 +0.000
–0.010 Same As Pin Depth
OUTPUT – NF 207 +0.000
–0.010
58, 59,
87, 97 TEST – A +0.000 –0.003
97 TEST – N 207 –0.000
+0.003 207 +0.000 –0.003
TEST – NF 207 +0.000
–0.003 Same As Pin Depth
TEST – S2–0.0025
–0.0035
TEST – SF2–0.0003
–0.0007
60, 63 INPUT – NF 207 +0.000
–0.020 N/A
60 OUTPUT – NF
60, 63 TEST – A +0.000
–0.003 Same As Pin Depth
TEST – N 207 +0.000
+0.003 207 +0.000 –0.003
TEST – NF 207 +0.000
–0.003 Same As Pin Depth
62 INPUT – NF 207 +0.000
–0.020
OUTPUT – NF
62 TEST – N 207 –0.000
+0.018 207 +0.000 –0.018
TEST – NF 207 +0.000
–0.018 Same As Pin Depth
Legends and Notes
Typical Model Number:
97SF50
Connector Type Abbreviations:
N = Type N male
NF = Type N female
A = GPC-7
Impedance
Connector Type (Test Port
Connector on Bridges and
SWR Autotesters
Impedance
Table 3. Pin-Depth Tolerance, SWR
Autotesters and Bridges
TEFLON WASHER
NOTE
The teflon washer is shown on a GPC-7 connec-
tor. A similar washer may be installed on any
WILTRON precision connectors.
Figure 4. Tuning Washer on GPC-7 Connector
SWR OMM 5

d. Avoid Mechanical Shock. SWR Autotesters
and bridges are designed to withstand years of
normal bench handling. However, do not drop or
otherwise treat them roughly. They are labora-
tory-quality devices, and like other such devices,
they require careful handling.
e. Keep SWR Autotester or Bridge Connectors
Clean. The precise geometry that makes the
SWR Autotester’s or bridge’s high performance
possible can be disturbed by dirt and other con-
taminants adhering to connector interfaces.
When not in use, keep the SWR Autotester or
bridge connectors covered. Refer to paragraph 8
for cleaning instructions.
6. PERFORMANCE VERIFICATION
Performance verification consists of measuring the
directivity of the SWR Autotester or bridge and
measuring connector pin depth.
7. DIRECTIVITY MEASUREMENTS.
Directivity measurements are frequency limited. For
frequencies 2 GHz and above an air line technique
is used to obtain a precise measurement; below 2
GHz where an air line is not effective, a go-no go test
must be used.
Table 4 lists recommended test equipment for per-
forming these measurements. Measurement proce-
dures are given below.
Measuring the directivity of 97S50 and 97SF50 SWR
Autotesters at 2 GHz and above requires use of a
19SF50 or 19S50 Air Line. The WSMA connectors on
these components are designed to mate with SMA
connectors. When mating two WSMA connectors,
compensation washers are required. The only excep-
tions are the WSMA Open/Short and the sweep gen-
erator RF OUTPUT connector, which have been op-
timized for use with WSMA. An envelope containing
six or more of these washers is packaged with each
air line. Figure 9, beginning on page 12, provides a
procedure for installing these washers.
Instrument Required Characteristics Recommended Model and Manfacturer
Scalar Network Analyzer System
Sweep Generator
Leveled Output: ±1.0 dB
Frequency Range: 2 – 18 GHz
Scalar Network Analyzer
Vertical Sensitivity: 0.5 dB/Div.
Variable Offset Control
WILTRON 562 SNA and 68147B
Synthesized Sweep Generator, with
560-10BX Cable
OR
WILTRON 5447A Scalar
Measurement System
Air Line SWR: 1.002 (GPC-7 Connector)
SWR: 1.006 (Type N/NF
Connector)
SWR: 1.006 (WSMA Connector)
WILTRON 18 Series
WILTRON 19 Series
Termination 20 dB Offset WILTRON 29 Series
Precision Termination
50 ± 0.5 Ohms
GPC-7 Test Port Connector
Type N Test Port Connector
WSMA Female Test Port Connector
WSMA Male Test Port Connector
75 ± 0.5 Ohms
Type N Test Port Connector
BNC Test Port Connector
WILTRON:
28A50-1
26N50
28S50
28SF50
WILTRON:
26N75
26B75
Table 4. Recommended Test Equipment
6SWR OMM

a. Measuring Directivity At 2 GHz and Above.
1. Connect test setup as shown in Figure 5.
2. Press LINE key on signal source to OPERATE.
3. Press POWER key on network analyzer to ON.
4. Press SYSTEM key on signal source, then se-
lect the Reset softkey, from the displayed
menu.
5. Set signal source for frequency range of de-
vice-under-test (DUT) and for maximum pos-
sible power, as described below.
(a) Press CW/SWEEP SELECT key.
(b) Select the Analog softkey from the dis-
played menu.
(c) Select the Edit F1 softkey from the dis-
played menu.
(d) Using the Cursor Control Key or Rotary
Data Knob, edit the F1 parameter to
equal the low-end frequency of the SWR
Autotester or Bridge under test.
(e) Select the Edit F2 softkey and repeat
step (d) for the high-end frequency.
(f) Select the Edit L1 softkey, and repeat
step (d) to display the source’s maximum
power level value.
6. Press SYSTEM FUNCTION MENU key on net-
work analyzer.
7. Using MENU up-down keys: Highlight RE-
SET, then press SELECT key.
8. Press CHANNEL 2 key to OFF.
9. Press GRATICULE ON/OFF key to ON.
10. Press CHANNEL 1 MENU key.
11. Using MENU up-down keys: Highlight RE-
TURN LOSS, then press SELECT key.
12. Press CALIBRATION key.
AIR LINE
OPEN/SHORT
34-SERIES
ADAPTER
562 SCALAR NETWORK ANALYZER
20 dB OFFSET
CONNECT DASHED LINE CONNECTIONS
WHEN DIRECTED BY PROCEDURE
SWR AUTOTESTER OR
BRIDGE UNDER TEST
(IF TESTING BRIDGE, USE 560-7 SERIES
DETECTOR INSTEAD OF 10 BX CABLE
560-10BX CABLE
REFERENCE TERMINATION
(<2 GHz MEASUREMENTS)
68147B SYNTHESIZED SWEEP GENERATOR
Figure 5. Test Equipment Setup for Directivity Measurement
SWR OMM 7

13. Using MENU up-down keys: Highlight START
CAL then press SELECT key.
14. Connect SWR Autotester to INPUT A, if you
have not done so yet.
15. Connect beadless end of air line to test port on
SWR Autotester, paying careful attention to
making a good connection. The displays
shown in Figure 6 indicate good and bad con-
nections.
16. Connect OPEN to air line and press SELECT
key.
17. Connect SHORT to air line and press SELECT
key.
18. Connect 20 dB Offset to air line and press
SELECT key.
19. Press CHANNEL 1 MENU key.
20. Using MENU up-down keys: Highlight REF
LINE, then press SELECT key.
21. Using DATAENTRY knob, set reference line to
4th graticule line from top (Figure 7).
22. Press CHANNEL1 AUTOSCALE key.
23. Press CHANNEL 1 OFFSET/RESOLUTION
key.
REFERENCE LINE POSITION
Figure 7. Reference Line Position
Figure 6. Examples of Good and Bad Air Line Connections
GOOD
BAD
8SWR OMM

24. Using MENU up-down keys: Highlight
OFFSET dB,then press SELECT key.
25. Using DATA ENTRY/CURSOR knob, align the
Channel 1 signal with the reference line (Fig-
ure 8).
26. Using MENU up-down keys: Highlight RESO-
LUTION dB/DIV, then press SELECT key.
27. Read OFFSET value from top of display.
This is the value of the 20 dB Offset.
28. Observing the displayed ripple pattern, select
the ripple with the greatest amplitude and
position its average point (see NOTE) on the
reference line.
NOTE
The average point is approximately
halfway between the peak and
trough values for ripples 3 dB or
less. For ripples greater than 3 dB,
refer to Table 6.
29. Measure the peak-to-peak value of the se-
lected ripple.
30. In the “REF ±X, Peak to Peak Ripple, dB”
column of Table 6, find the value nearest to
the peak-to-peak signal value measured in
step 29.
31. Read the coordinate value from the “X dB
Below Reference” column.
32. Add the dB value from step 30 to the value
read in step 31. The sum is the worst-case
directivity of the SWR Autotester or bridge. It
should equal or exceed the specification in
Table 1 or 2.
b. Directivity Measurements Below 2 GHz.
1. Set up equipment as shown in Figure 5.
2. Perform steps 2 thru 13 of subparagraph a.
3. Connect termination to test port of SWR
Autotester or bridge being measured*.
4. Press CHANNEL 1 MENU key.
5. Using MENU up-down keys: Highlight REF
LINE, then press SELECT key.
6. Using DATAENTRY knob, set reference line to
midscale.
7. Press CHANNEL 1 OFFSET/RESOLUTION
key.
8. Using MENU up-down keys: Highlight OFF-
SET dB, then press SELECT key.
9. Using DATA ENTRY knob, set OFFSET dB for
the directivity value of the SWR Autotester or
bridge being measured.
10. Using MENU up-down keys: Highlight RESO-
LUTION dB/DIV, then press SELECT key.
11. Using DATA ENTRY knob, set RESOLUTION
dB/DIV for a convenient value.
12. Observe analyzer display. If measured direc-
tivity signal is below the reference line, then
the directivity is within the specified value.
REFERENCE LINE
Figure 8. Signal Aligned With the Reference Line
* The return loss of the termination must be higher than the
directivity of the SWR Autotester or bridge being measured.
The WILTRON terminations recommended in Table 4 meet
this requirement.
SWR OMM 9

c. Pin Depth Measurements.
Gauging sets for measuring terminations are avail-
able from WILTRON. Table 5 provides a listing that
correlates each SWR Autotester and bridge type
with its appropriate gauging set. Instructions for
gauging air line connectors are provided with gaug-
ing set.
8. MAINTENANCE
WILTRON recommends that no maintenance other
than cleaning be attempted by customer. The SWR
Autotester or bridge should be returned to WIL-
TRON for repair and/or service when needed.
Clean connector interfaces with clean cotton swab
dampened with alcohol.
CAUTION
Excessive pressure when cleaning can
damage the center conductor support
bead in the SWR Autotester or Bridge.
Ensure that the cotton swab is small
enough to fit into the connector with-
out applying pressure to the center
conductor. When cleaning, limit the
pressure so as to lightly contact the
connector. To obtain cotton swabs that
are smaller than the standard type
available in most retail outlets, try
contacting a medical-lab-type supply
center.
CAUTION
If installed, do not disturb the teflon
washer on the center conductor (refer to
paragraph 5c).
Model Connector Type Gauging Set
Model
60A50, 58A50,
87A50, 87A50-1
63A50, 59A50,
97A50, 97A50-1
GPC–7 01-161
60N50, 62N75,
63N50, 97N50,
97N50-1 N Male
01-163
60NF50, 62NF75,
63NF50, 97NF50,
97NF50-1 N Female
97S50, 97S50-1 WSMA Male 01-162
97SF50, 97SF50-1 WSMA Female
Table 5. Available Gauging Sets
10 SWR OMM