1825 Manual

MODELS 1825 & 1827
Economical Power Sensor Calibrators
Instruction Manual
PN# 1825-901-01CD
Publication Date: April 2007
REV. E
TEGAM INC.
MODELS 1825 & 1827
ECONOMICAL POWER SENSOR CALIBRATORS
MODEL 1825
MODEL 1827
Instruction Manual
PN# 1825-901-01CD
Publication Date: April 2007
REV. E
NOTE: This user’s manual was as current as possible when this product was manufactured. However, products are
constantly being updated and improved. Because of this, some differences may occur between the description in this
manual and the product received.
TEGAM is a manufacturer of electronic test and measurement equipment for metrology,
calibration, and production test. We also provide repair, calibration, and other support
services for a wide variety of test and measurement equipment including RF power sensor
calibration systems, RF attenuation measurement systems, resistance standards, ratio
transformers, arbitrary waveform generators, micro-ohmmeters, LCR meters, handheld
temperature calibrators, thermometers, humidity and temperature control devices, and
more.
TEGAM also repairs and calibrates test and measurement equipment formerly
manufactured by Electro-Scientific Industries (ESI), Gertsch, Keithley Instruments, Lucas
Weinschel, and Pragmatic Instruments. A complete list can be viewed on our Product
Service Directory at www.tegam.com
For more information about TEGAM and our products, please visit our website at
www.tegam.com: or contact one of our customer service representatives at
sales@tegam.com or 800-666-1010.
Ten Tegam Way,
Geneva, Ohio 44041
Telephone: (440) 466-6100
Fax: (440) 466-6110
E-mail: sales@tegam.com
b
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
Table of Contents
I
INSTRUMENT DESCRIPTION............................................................................1-1
Abbreviations and Acronyms .................................................................... 1-2
Figure 1.1 Model 1825 ............................................................................ 1-2
Figure 1.2 Model 1827 ............................................................................ 1-2
Description of Equipment ........................................................................ 1-3
Functional Description........................................................................ 1-3
Physical Description ........................................................................... 1-3
Specifications ................................................................................... 1-4
Table 1.1 Physical and Electrical Specifications ................................. 1-4
Additional Equipment .............................................................................. 1-5
Table 1.2 Additional Equipment Required .............................................. 1-5
Applications........................................................................................... 1-5
Figure 1.3 Typical Setup for Power Sensor Calibration using 1825 ............ 1-5
Figure 1.4 Typical Setup for Power Sensor Calibration using 1827 ............ 1-6
II
PREPARATION FOR USE ..................................................................................2-1
Unpacking & Inspection........................................................................... 2-2
Mounting .............................................................................................. 2-2
Safety Information & Precautions ............................................................. 2-2
Terms in this Manual ......................................................................... 2-2
Terms as Marked on Equipment........................................................... 2-2
Symbols........................................................................................... 2-3
Grounding the Equipment ................................................................... 2-3
Danger Arising from the Loss of Ground ............................................... 2-3
Use the Proper Fuse........................................................................... 2-3
Use in Proper Environment ................................................................. 2-4
Do Not Use in Explosive Environments.................................................. 2-4
Do Not Block Air Vents on Rear Panel ................................................... 2-4
Do Not Operate without Covers ........................................................... 2-4
Figure 2.1 Model 1825 and 1827 AC INPUT POWER and FUSE Location .......... 2-4
Servicing Safety Summary ...................................................................... 2-4
Do not Service Alone ......................................................................... 2-4
Use Care when Servicing with Power On or Off ...................................... 2-5
Power Source ................................................................................... 2-5
Line Voltage Selection............................................................................. 2-5
III
OPERATING INSTRUCTIONS............................................................................3-1
1825 and 1827 Front Panel Description ..................................................... 3-2
Figure 3.1 Model 1825 and 1827 Front Panel ......................................... 3-2
1825 and 1827 Rear Panel Description ...................................................... 3-4
Figure 3.2 Model 1825 and 1827 Rear Panel.......................................... 3-4
RF Power Sensor Calibration .................................................................... 3-4
Connecting the Model 1825 RF Power Sensor Calibrator .......................... 3-5
Figure 3.3 1825 Connections for Power Sensor Calibration ................. 3-5
Connecting the Model 1827 RF Power Sensor Calibrator .......................... 3-5
Figure 3.4 1827 Connections for Power Sensor Calibration ................. 3-6
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
c
Table of Contents
RF Power Level Measurement.............................................................. 3-6
RF Power Level Measurement with a DVM only.................................. 3-6
RF Power Level Measurement with a DVM and an RVG ....................... 3-7
Figure 3.5 Connections for Using the 1825 or 1827 with an RVG .... 3-7
RF Power Sensor Calibration Factor...................................................... 3-8
Calibrating Sensors with a Reference CF ............................................... 3-9
Calibrating Sensors Using an Adapter or Attenuator ............................... 3-9
Additional Information ............................................................................ 3-10
IV
THEORY OF OPERATION ..................................................................................4-1
Principal of DC Substitution ..................................................................... 4-2
Precision Power Measurement .................................................................. 4-2
Self-Balancing Bridge Circuits.............................................................. 4-2
Figure 4.1 Simplified Schematic of the 1825/1827 Bridge Circuit ......... 4-3
Power Measurements ......................................................................... 4-3
Controlling Thermistor Temperature..................................................... 4-4
Figure 4.2 Simplified Schematic of the 1825/1827 Heater Circuit......... 4-5
Calculating Uncertainty ........................................................................... 4-5
Mismatch Uncertainty (MER) ................................................................ 4-6
Gamma Correction ....................................................................... 4-6
Instrumentation Uncertainty (IE) ......................................................... 4-7
Table 4.1 Typical Instrumentation Error Analysis (IE) ......................... 4-7
VI
SERVICE INFORMATION ..................................................................................5-1
Warranty .............................................................................................. 5-2
Warranty Limitations .............................................................................. 5-2
Statement of Calibration ......................................................................... 5-2
Contact Information ............................................................................... 5-2
Changing the Power Fuse ........................................................................ 5-3
Figure 5.1 Location of the FUSE........................................................... 5-3
Preparation for Calibration or Repair Service .............................................. 5-3
Expedite Repair & Calibration Form ...................................................... 5-4
d
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
Instrument Description
INSTRUMENT DESCRIPTION
PREPARATION FOR USE
OPERATING INSTRUCTIONS
THEORY OF OPERATION
SERVICE INFORMATION
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
1-1
Instrument Description
Abbreviations And Acronyms
The following list contains all abbreviations used throughout this manual. Abbreviations and
acronyms that are not listed conform to MIL-STD-12D.
CW Continuous Wave
SUT Sensor Under Test
DVM Digital Voltmeter
ESDS Electrostatic Discharge Sensitive
NIST National Institute of Standards and Technology
RF Radio Frequency
DC Direct Current
UUT Unit Under Test
Figure 1.1 Model 1825
Figure 1.2 Model 1827
1-2
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
Instrument Description
Description Of Equipment
Functional Description
The Model 1825 is designed to calibrate power meter sensors in the 10 MHz to 18 GHz frequency
range. The Model 1825 does not have any settings or controls other than the POWER and
FLOAT/GROUND switches. Measurements are made with an external DVM supplied by the user.
The Model 1825 provides accurate measurements for standard calibration points that are directly
traceable to the National Institute of Standards and Technology (NIST).
The Model 1827 calibrates power meter sensors in the 100 kHz to 18 GHz frequency range. Since
most single RF signal generators do not cover this entire frequency band, it is usually necessary
to use two. For this reason the Model 1827 has two RF signal generator inputs that are selected
by a front panel switch. Measurements are made as with the Model 1825.
Both the Models 1825 and 1827 precisely and accurately detect RF power through a temperature
controlled thermistor power standard and DC substitution bridge. This enables the operator to
accurately calculate an RF power level which is then used for comparison with the power level
measured by the Sensor Under Test (SUT). The ratio of the two power levels is the SUT’s
calibration factor. Refer to Section III for a more detailed discussion of the functionality of these
instruments.
Physical Description
Refer to Table 1-1 for the physical and electrical specifications of the Model 1825 and 1827. The
Model 1825 front panel contains the INPUT POWER switch as well as the SENSOR, RF IN, and
VOLTMETER connectors. The Model 1827 front panel contains the same except there are two RF
inputs, RF IN1 and RF IN2, with an LED indicator next to each, and a toggle switch to select which
RF input is used. The rear panel of both contain the input power connector and fuse,
FLOAT/GROUND switch, and vents for airflow. Both models are designed to sit on a bench but can
be mounted in a 19” rack with rack mount kit RM-1825 (sold separately, call TEGAM for details).
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
1-3
Instrument Description
Specifications
Table 1.1 lists the physical and electrical specifications of the Model 1825 and 1827.
Table 1.1 Physical and Electrical Specifications
Model
1825
1827
Frequency Range
10 MHz to 18 GHz
100 kHz to 18 GHz
Power Range
0.01 to 25 mW (-20 to +14 dBm) 0.01 to 25 mW (-20 to +14 dBm)
DC Substitution Bridge ±0.003%
±0.003%
Accuracy
RF Impedance
50 Ohms nominal
50 Ohms nominal
SWR (SENSOR)
≤ 1.14
≤ 1.14
Power Linearity
<0.1% from 1 to 10 mW
<0.1% from 1 to 10 mW
Insertion Loss (RF IN) 6 dB nominal, 9.5 dB max
6 dB nominal, 10 dB max
Individual calibrations 10 to 100 MHz in 10 MHz steps
100, 200, 455 kHz
traceable to NIST
0.1 to 2 GHz in 50 MHz steps
1, 1.25, 3, 5 MHz
supplied at the
2 to 4 GHz in 100 MHz steps
10 to 100 MHz in 10 MHz steps
following frequencies:
4 to 12.4 GHz in 200 MHz steps
0.1 to 2 GHz in 50 MHz steps
12.75 to 18 GHz in 250 MHz
2 to 4 GHz in 100 MHz steps
steps
4 to 12.4 GHz in 200 MHz steps
12.75 to 18 GHz in 250 MHz
steps
Calibration Factor
+/-1.00% from 0.01 to 10 GHz
+/-0.80% from 0.1 to 10 MHz
Accuracy
+/-1.10% from 10 to 18 GHz
+/-1.00% from 0.01 to 10 GHz
+/-1.10% from 10 to 18 GHz
Calibration Factor Drift <0.5% per year
<0.5% per year
Connectors
SENSOR
N-type Female
N-type Female
RF IN
SMA Female
SMA Female (X2)
VOLTMETER
Binding Post, standard 0.75”
Binding Post, standard 0.75”
spacing for banana plugs
spacing for banana plugs
Temperature
Operating
+12° to +32° C (+54° to +90° F) +12° to +32° C (+54° to +90° F)
-40° to +75° C (-40° to +167° F) -40° to +75° C (-40° to +167° F)
Storage
Warm up time
2 hours minimum from
2 hours minimum from
instrument power up
instrument power up
Power Requirements
100VA, 50 to 400 Hz, 105 to 125
100VA, 50 to 400 Hz, 105 to 125
Vac standard or 210 to 250 Vac
Vac standard or 210 to 250 Vac
with a factory installed option.
with a factory installed option.
Input Power Fuse
Slo-Blo, 0.8 Amp for 110 Vac or
Slo-Blo, 0.8 Amp for 110 Vac or
0.5 Amp for 220 Vac
0.5 Amp for 220 Vac
Weight
16.2 lbs (7.3 kg)
17.7 lbs (8.03 kg)
Physical Dimensions
Height
3.5 in (88.9 mm)
3.5 in (88.9 mm)
Width
18 in (457.2 mm)
18 in (457.2 mm)
Depth
15.4 in (391.2 mm)
15.4 in (391.2 mm)
Rack Mounting
Can be mounted in a standard
Can be mounted in a standard
19” rack with rack mount kit RM19” rack with rack mount kit RM1825.
1825.
1-4
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
Instrument Description
Additional equipment
Table 1-2 lists the additional equipment required to calibrate RF power sensors with the Model
1825 and 1827. The description for each piece of equipment listed states the minimum
recommended requirements for that piece of equipment. There may be many models that meet
the minimum requirements; it is up to the operator to select the specific model. Measurement
uncertainty will vary depending on the additional equipment used. Please refer to the
specifications for the particular model number to get that information.
Signal Generator
DVM
Table 1.2 Additional Equipment Required
Continuous Wave, 6dBm minimum power output. 10
MHz to 18GHz Frequency Range for Model 1825. 100
kHz to 18 GHz Frequency Range for Model 1827, two
may be required to cover entire Frequency Range.
DC Volts, 6½-digit minimum.
RF Power Meter
Compatible with the sensor under test.
APPLICATIONS
The TEGAM Model 1825 and 1827 Power Sensor Calibrator was designed for the transfer of
calibration factors to power meter sensors. While neither model is designed for remote
programming, the process of calibrating power sensors can be automated if the additional
equipment used can be remotely programmed.
Figure 1.3 Typical Setup for Power Sensor Calibration using Model 1825
Signal Generator
DVM
Power Meter
+ -
SUT
RF Out
RF IN
VOLTMETER
SENSOR
Model 1825
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
1-5
Instrument Description
Figure 1.4 Typical Setup for Power Sensor Calibration using Model 1827
High Frequency
Signal Generator
RF Out
DVM
Low Frequency
Signal Generator
Power Meter
+ -
SUT
RF Out
RF IN1
RF IN2
VOLTMETER
SENSOR
Model 1827
1-6
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
Preparation for Use
INSTRUMENT DESCRIPTION
PREPARATION FOR USE
OPERATING INSTRUCTIONS
THEORY OF OPERATION
SERVICE INFORMATION
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
2-1
Preparation for Use
Unpacking & Inspection:
Each 1825 and 1827 is put through a series of electrical and mechanical inspections before
shipment to the customer. Upon receipt of your instrument unpack all of the items from the
shipping carton and inspect for any damage that may have occurred during transit. Report any
damaged items to the shipping agent. Retain and use the original packing material for reshipment
if necessary.
Upon Receipt, inspect the carton for the following items:
Model 1825 or 1827 RF Power Sensor Calibrator
Model 1825 and 1827 Operating Manual (CD)
3.5” floppy disk with “Cal Factor Calculator”
Microsoft Excel Spreadsheet
Power Cord
P/N 1825-901-01CD
P/N 068-21
Mounting
The Model 1825 and 1827 are shipped with four plastic feet mounted to the bottom cover. When
the Model 1825/1827 is placed on a bench or table, these feet support the instrument. The Model
1825 or 1827 can also be rack mounted in a standard 19” rack using the optional rack adapter kit
RM-1825.
!
Safety Information & Precautions:
The following safety information applies to both operation and service personnel. Safety
precautions and warnings may be found throughout this instruction manual and the equipment.
These warnings may be in the form of a symbol or a written statement. Below is a summary of
these precautions.
Terms in This Manual:
CAUTION statements identify conditions or practices that could result in damage to the equipment
or other property.
WARNING statements identify conditions or practices that could result in personal injury or loss of
life.
Terms as Marked on Equipment:
CAUTION indicates a personal injury hazard not immediately accessible as one reads the marking,
or a hazard to property including the equipment itself.
DANGER indicates a personal injury hazard immediately accessible as one reads the marking.
2-2
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
Preparation for Use
Symbols:
As Marked in This Manual:
!
This symbol denotes where precautionary information may be found.
As Marked on Equipment:
!
CAUTION – Risk of Danger
DANGER – Risk of Electric Shock
Earth Ground Terminal
l
On
O
Off
Frame or Chassis Terminal
Earth Ground Terminal
Alternating Current
Grounding the Equipment
This product is grounded through the grounding conductor of the power cord.
WARNING: To avoid electrical shock or other potential safety hazards, plug the power cord into a
properly wired receptacle before using this instrument. The proper grounding of this instrument is
essential for safety and optimizing instrument operation.
Danger Arising from Loss of Ground
WARNING: If the connection to ground is lost or compromised, a floating potential could develop
in the instrument. Under these conditions all accessible parts, including insulating parts such as
keypads and buttons could develop a hazardous voltage and put the user at risk.
!
Use the Proper Fuse
To avoid fire hazard, use only the correct fuse type as specified for the AC power supply in the
“Instrument Description” or “Service Information” sections of this manual. Please note that the
fuse rating for 100/120-volt power supply is different than the rating for 200/240-volt power
supply.
Refer fuse replacement to qualified service personnel.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
2-3
Preparation for Use
Use in Proper Environment
Normal calibration laboratory practice dictates that the environment should be closely controlled.
This will minimize errors introduced by temperature and humidity changes. A nominal
temperature of +23°C (+73.4°F) provides a good working condition. A tolerance of ±1°C gives
allowable temperature spread. Controlled temperatures also stabilize the aging process of the
standards.
CAUTION: The Model 1825 and 1827 have a specified ambient temperature range of +12° to
+32°C (+54° to +90°F). Operating beyond these limits can affect the accuracy of the instruments
and damage internal circuitry.
CAUTION: When the Model 1825 or 1827 is to be stored for extended periods, pack the
instrument into a container. Place container in a clean, dry, temperature-controlled location. If
instrument is to be stored in excess of 90 days, place desiccant with items before sealing
container. The safe environmental limits for storage are -40° to +75°C (-40° to +167°F) at less
than 95% non-condensing relative humidity.
Do Not Use in Explosive Environments
CAUTION: The 1825/1827 is not designed for operation in explosive environments.
Do Not Block Air Vents on Rear Panel
CAUTION: The Model 1825 and 1827 have an air intake and exhaust on the back panel of the
instrument. When installing the Model 1825/1827, ensure there is at least two inches of space
behind the instrument for airflow. DO NOT set the instrument on its rear panel as its airflow will
be restricted and may result in damage to the internal circuitry.
Do Not Operate Without Covers
WARNING: This device should be operated with all panels and covers in place. Operation with
missing panels or covers could result in personal injury.
Figure 2.1 Model 1825 and 1827 AC INPUT POWER and FUSE location
FOR QUALIFIED SERVICE PERSONNEL ONLY
!
Servicing Safety Summary:
Do Not Service Alone
Do not perform service or adjustment on this product unless another person capable of rendering
first aid is present.
2-4
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
Preparation for Use
Use Care When Servicing with Power On or Off
Dangerous voltages may exist at several points in this product. To avoid personal injury or
damage to this equipment, avoid touching exposed connections or components while the power is
on. Assure that the power is off by unplugging the instrument when removing panels, soldering,
or replacing components.
WARNING: The instrument power source is electronically controlled meaning that there is power
present throughout the instrument even when the instrument is in the OFF state.
Always unplug the instrument and wait 5 minutes before accessing internal components.
Power Source
This product is intended to connect to a power source that will not apply more than 250V RMS
between the supply conductors or between either supply conductor and ground. A protective
ground connection by way of the grounding conductor in the power cord is essential for safe
operation.
!
Line Voltage Selection:
CAUTION: DO NOT APPLY POWER TO THE INSTRUMENT BEFORE READING THIS SECTION:
The standard power supply in a Model 1825 or 1827 operates with a line voltage of 105 to 125
Vac at 50 to 400 Hz. A 210 to 250 Vac power supply can be ordered as a factory installed option.
Each power supply requires a different fuse. It is strongly recommended that the line voltage,
frequency, and fuse type be verified for the type of power supply in the unit before powering it.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
2-5
Operating Instructions
INSTRUMENT DESCRIPTION
PREPARATION FOR USE
OPERATING INSTRUCTIONS
THEORY OF OPERATION
SERVICE INFORMATION
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-1
Operating Instructions
Model 1825 and 1827 Front Panel Description
TEGAM
Power
Sensor
Calibrator Model
Model1825
1825
RF RF
Power
Sensor
Calibrator
SENSOR
VOLTMETER
POWER
RF IN
READY
ERROR
POWER ON
Indicator
POWER
Switch
ERROR
Indicator
FREQUENCY RANGE: 10 MHz to 18 GHz
POWER RANGE: 10 μW to 25mW
READY
Indicator
SENSOR
Connector
RF IN
Connector(s)
VOLTMETER
Switch
RF IN
Indicators
RF IN
Switch
TEGAM
Power
Sensor
Calibrator Model
Model1827
1827
RF RF
Power
Sensor
Calibrator
SENSOR
VOLTMETER
POWER
RF IN 1
READY
ERROR
FREQUENCY RANGE: 100 kHz to 18 GHz
POWER RANGE: 10 μW to 25mW
RF IN 2
Figure 3.1 Model 1825(top) and 1827(bottom) Front Panel
POWER Switch (Both Models)
Switches the power input to the instrument on and off. Has a built-in indicator that is illuminated
when power is on. See POWER ON indicator.
POWER ON Indicator (Both Models)
Illuminates when instrument power is on. It is built into the POWER switch.
READY Indicator (Both Models)
This green LED illuminates when the RF power standard has reached its internal operating
temperature of 60°C. Allow two hours for the power standard to reach this temperature and
ensure the READY indicator stays illuminated during RF power sensor calibrations.
ERROR Indicator (Both Models)
The ERROR indicator is a red LED that illuminates for any condition preventing the Type IV Bridge
circuit from balancing. When the ERROR indicator becomes illuminated, stop any calibration and
contact TEGAM for assistance.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-2
Operating Instructions
SENSOR Connector (Both Models)
N-type female connector for the SUT. This connector provides the RF power to the SUT. The RF
power applied to RF IN connector is applied equally to the SUT and the internal power standard.
The fact that equal RF power is applied to both the power standard and the SUT is what allows
the calibration factor of the SUT to be determined.
VOLTMETER Connectors (Both Models)
The VOLTMETER Connectors are spade-lug connecting posts/banana jacks. These connectors
complete the DC path between the Model 1825 and a digital voltmeter with at least 6½-digit
resolution. DC voltage present across the VOLTMETER connectors is equivalent to the voltage
across the thermistor element. The red connector is for positive (+) DC voltage and the black
connector is for negative (-) DC voltage.
RF IN Connector (Model 1825)
SMA female that connects to signal generator output. The RF power that comes in this connector
is applied equally to the SUT and the power standard. The fact that equal RF power is applied to
both the power standard and the SUT is what allows us to determine the calibration factor of the
SUT. There is about 6 to 9.5 dB of insertion loss in the RF IN path.
RF IN 1 and RF IN 2 Connectors (Model 1827)
Both are SMA female that connects to signal generator outputs. Two inputs are provided because
it is often necessary to use two different signal generators to cover the 100 KHz to 18 GHz
frequency range of the Model 1827. The RF power that comes in this connector is applied equally
to the SUT and the power standard. The fact that equal RF power is applied to both the power
standard and the SUT is what allows us to determine the calibration factor of the SUT. There is
about 6 to 10 dB of insertion loss in the RF IN path.
RF IN 1/RF IN 2 Switch (Model 1827)
Toggle switch that is used to select which RF Input is active. The switch position indicates which
input is active. When the switch is up RF IN 1 is active, when the switch is down RF IN 2 is active.
This switch allows RF sources to be changed without disconnecting and reconnecting cables.
RF IN 1 and RF IN 2 Indicators (Model 1827)
This green LED illuminates when the RF input next to it is active.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-3
Operating Instructions
Model 1825 and 1827 Rear Panel Description
AC INPUT POWER
OD602
5-24H
FUSEGROUND
FLOAT
Air Vent
with Filter
AC INPUT POWER
connector
AC input
power FUSE
FLOAT/GROUND
switch
Exhaust Fan
Figure 3.2 Model 1825 and 1827 Rear Panel
Air Vent with Filter
Air Vent allows air to flow into the Model 1825/1827 to keep the internal components from
overheating. The filter keeps debris from entering the instrument. Ensure there is at least two
inches of space behind the instrument for proper airflow.
AC INPUT POWER connector
Three prong connector mates with AC power cord supplied with unit.
AC input power FUSE
Protects instrument from an over-current condition. A 0.8 Amp fuse is used with the standard 110
Vac power supply, a 0.5 Amp is used with the optional 220 Vac power supply.
FLOAT/GROUND Switch
The FLOAT/GROUND Switch is a two position toggle switch located on the rear panel. This switch
connects and disconnects the bridge board ground to chassis ground; the up position connects
the bridge board to ground and the down position disconnects the bridge board from ground
(floats). Normal operation is with the switch in the GROUND (up) position. If the LO (-) input of
the external DVM is grounded, then the switch should be in the FLOAT (down) position.
Exhaust Fan
The Exhaust Fan causes air to flow out of the Model 1825/1827 to keep the internal components
from overheating. Ensure there is at least two inches of space behind the instrument for proper
airflow.
RF Power Sensor Calibration
To determine the calibration factor (the percentage of power applied to a power sensor that will
actually be measured by the power meter), the power measured by the sensor is compared to a
known power level. The known power level can either be set to a known level by a highly accurate
source, such as with the System II Automatic Calibration System, or it can be accurately
measured as with the Model 1825 or 1827. Contact TEGAM for more information on the System
IIA. Once the power level is known, the calibration factor can be calculated. The following
paragraphs describe this process.
Connecting The Model 1825 RF Power Sensor Calibrator
Before any measurements are taken, the Model 1825 must be connected as shown in Figure 3.3.
The RF IN is connected to the output of the chosen signal generator, which should be 50 Ohm
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-4
Operating Instructions
nominal impedance. The RF IN is a female SMA connector; any adapters used to connect it to the
signal generator output are referenced out and should not affect the sensor calibration. However,
proper care, cleaning, and torquing of coaxial connectors should be practiced to reduce insertion
loss and extend the life of the connectors. Also, a low loss coaxial cable is recommended to avoid
an excessive power loss. The VOLTMETER red and black connectors are connected to the DVM DC
voltage positive and negative input connectors respectively. The VOLTMETER connectors are
binding posts/banana jacks so banana plugs or spade lugs will mate with them.
Connect the Sensor Under Test (SUT) to an appropriate power meter. Zero and “cal” the power
meter and sensor in accordance with the manufacturer’s operating instructions. The input of the
SUT connects to the 50 Ohm N-type female SENSOR connector on the Model 1825. If any
adapters, attenuators, or matching pads are needed they should be characterized and taken into
account as described later in this chapter.
Signal Generator
Power Meter
DVM
RF Out
-
SUT
+
RF IN
RED BLACK
VOLTMETER
SENSOR
Model 1825
Figure 3.3 1825 Connections for Power Sensor Calibration
Connecting The Model 1827 RF Power Sensor Calibrator
The Model 1827 is connected much the same way as the Model 1825. The only difference is the
fact that the Model 1827 has two RF IN connectors. The purpose of having two RF IN connectors
is to accommodate two signal generators. Often, it is necessary to use two signal generators to
cover the entire frequency range of the 1827. The RF inputs are activated using a toggle switch
and an LED next to each output indicates which is active. This way signal sources can be changed
just by flipping a switch without disconnecting and reconnecting RF cables.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-5
Operating Instructions
High Frequency
Signal Generator
RF Out
DVM
Low Frequency
Signal Generator
Power Meter
+ -
SUT
RF Out
RF IN1
RF IN2
RED BLACK
VOLTMETER
SENSOR
Model 1827
Figure 3.4 1827 Connections for Power Sensor Calibration
RF Power Level Measurement
The Model 1825 and 1827 precisely measure RF power in terms of a DC voltage change across
the Model 1825/1827 bridge circuit. This instrument measures the voltage change with a (at
least) 6½-digit resolution digital voltmeter (DVM) or the same DVM and reference voltage
generator (RVG) to obtain greater precision. The following paragraphs describe these two
methods of measurement.
RF Power Measurement With DVM Only
The Model 1825 and 1827 do not measure the RF power level directly. Instead, a DVM measures
DC voltages before and after the application of RF power to the thermistor in the Model
1825/1827. This necessitates calculation of the RF power level using data obtained from the DVM
measurements. To calculate the RF power level applied to the thermistor element, configure the
Model 1825 or 1827 and the DVM according to Figure 3.3 or 3.4 and measure the voltage across
the bridge with the DVM before the application of RF power and record it as V1. Then, measure
the voltage across the bridge after applying RF power and record that measurement as V2.
Determine the RF power level using the following steps:
First, calculate the level of proportional DC substituted power from the operating resistance and
DVM readings with the equation:
Pdc = (V1)2 – (V2)2
200
Where:
V1 = DVM reading across the bridge in the absence of RF power,
V2 = DVM reading across the bridge with RF power applied,
200 = nominal resistance of the 1825 thermistor in Ohms,
Pdc = DC substituted power which is proportional to the applied RF power
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-6
Operating Instructions
Next, calculate the applied RF power level using the applicable calibration factor provided with the
Model 1825 or 1827 and the level of DC substituted power:
PRF = Pdc
K2
Where:
PRF = Level of applied RF power,
Pdc = DC substituted power which is proportional to the applied RF power,
K2 = calibration factor of Models 1825 or 1827 traceable to NIST
RF Power Level Measurement With DVM And Reference Voltage Generator
When the applied RF power level becomes small, the change in voltage across the bridge also
becomes very small. In this situation, even a high-accuracy voltmeter magnifies measurement
uncertainties because the large DVM measurement scale has limited resolution. Use of a
reference voltage generator (RVG), like the one in Figure 3.5, minimizes voltmeter uncertainties
by enabling use of a measurement scale that has better resolution.
RVG
DVM
+
-
DPDT
VD
V1
VD
Signal Generator
Power Meter
V1
DUT
RF Out
RF IN
+
-
SENSOR
VOLTMETER
Model 1825 or 1827
Figure 3.5 Connections for Using the Model 1825 or 1827 with an RVG
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-7
Operating Instructions
When a reference voltage generator is used with the DVM, calculation of the RF power level
requires a different process. First, adjust the reference voltage generator to a voltage level
approximately equal to the Model 1825/1827 bridge output measured by a DVM when no RF
power is applied. Ensure stabilization of the RVG output throughout the entire measurement
period. Next, record the DVM reading with no RF power applied to the bridge and the double-pole,
double-throw switch in the “Measure V1” position. This value is (V1). Switch the DVM to a scale
with improved resolution for smaller power levels. Record the DVM reading with no RF power
applied and the double-pole, double-throw switch in the “Measure VD” position. This reading is the
difference between the Model 1825/1827 bridge output and the setting of the reference voltage
source (VD1). Finally, apply RF power to the bridge and record the voltmeter reading with the
double-pole, double-throw switch in the “Measure VD” position. This value is the difference
between the Model 1825/1827 output and RVG output including the proportional RF power effect
on the bridge circuit (VD2). Use these values and the following method to calculate the applied
level of RF power.
First, determine the level of DC substituted power using the measurements taken above with the
equation:
Pdc = (2V1 – VD2 + VD1) (VD2 - VD1)
200
Where:
V1 = DVM reading across the bridge in the absence of RF power,
VD1 = Difference between 1825/1827 bridge output with no RF applied and RVG output,
VD2 = Difference between 1825/1827 bridge output with RF applied and RVG output,
200 = nominal resistance of the 1825/1827 thermistor in Ohms,
Pdc = DC substituted power which is proportional to the applied RF power
Next, apply the mount calibration factor to find the level of RF power using the second equation:
PRF = Pdc
K2
Where:
PRF = Level of applied RF power,
Pdc = DC substituted power which is proportional to the applied RF power,
K2 = calibration factor of Models 1825 or 1827 traceable to NIST
RF Power Sensor Calibration Factor
Once the power level being applied to the SUT is measured, the sensor’s calibration factor can be
determined. Simply take a power reading (in mW) from the SUT’s power meter and divide that by
the power level obtained from the previous section (PRF). This ratio is the sensor’s calibration
factor. The calibration factor of the sensor is defined by:
Where:
K1S = cal factor of the SUT,
Pm = power reading from the power meter,
PRF = Level of applied RF power,
K1S = Pm
PRF
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-8
Operating Instructions
That equation can also be written:
K1S = (Pm)(K2)
Pdc
Where:
K1S = cal factor of the SUT,
Pm = power reading from the power meter,
K2 = calibration factor of Model 1825 or 1827 traceable to NIST
Pdc = DC substituted power which is proportional to the applied RF power
The cal factor can also be expressed as a percentage. To do this, simply multiply the cal factor
(K1S) by 100.
Calibrating Sensors With A Reference CF
Often, power sensors are calibrated with a Reference Calibration Factor (CF). This Reference CF is
used to align the meter and the sensor using the power meter’s “reference output” (typically 50
MHz). When the sensor is calibrated with a Reference CF, all the calibration factors of the sensors
are relative to a power meter’s reference output.
There are essentially two methods of calibrating sensors with a Reference CF. The first involves
applying the offset mathematically. To do this, measure the RF power level and determine the
sensor’s calibration factor at the reference frequency (usually 50 MHz). Then determine the ratio
of the desired reference cal factor to the cal factor that was calculated.
The ratio is an offset calculated by:
Where:
Koff = the calibration factor offset,
Kref = desired reference cal factor,
K1S = cal factor of the SUT
Koff = Kref
K1S
The rest of the sensor’s calibration factors are multiplied by Koff.
The second method of calibrating a power sensor with a Reference CF involves using the
calibration offset of the power meter itself. Simply set the calibration offset of the power meter to
the desired reference cal factor and cal adjust the meter using the reference output. Once the
power meter is adjusted, the rest of the cal factors can be obtained as described in the previous
sections; no further calculations are necessary.
Calibrating Sensors Using an Adapter or Attenuator
It may be necessary to use an adapter or attenuator to calibrate a particular power sensor with
the Model 1825 or 1827. If the sensor’s power range is less than the power range of the Model
1825/1827 (-20 to +14 dBm), then an attenuator is needed. If the sensor does not have an Ntype male connector then an adapter would be needed. A 50 to 75 Ohm matching pad is needed
to calibrate 75 Ohm sensors. Any device placed between the SENSOR connector and the SUT will
affect the calibration results and its loss (attenuation) must be characterized and corrected for.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-9
Operating Instructions
In order to correct for the loss of a device (adapter or attenuator), the attenuation of the device
must be measured at each frequency it will be used. There are many ways to measure
attenuation, a network analyzer is probably the most precise. Once the attenuation of the device
is measured, the “loss factor” at a particular frequency must be determined by:
KA = 10A/10
Where:
KA = the loss factor of the attenuator or adapter,
A = the measured attenuation in of the device in dB (should be a negative value)
To determine the calibration factor of the SUT, measurements are taken as previously described
in this chapter. The formula to determine the sensor’s calibration factor is slightly different:
K1S = (Pm)(K2)
(Pdc)(KA)
Where:
K1S = cal factor of the SUT,
Pm = power reading from the power meter,
K2 = calibration factor of Model 1825 or 1827 traceable to NIST,
Pdc = DC substituted power which is proportional to the applied RF power,
KA = the loss factor of the attenuator or adapter
Additional Information
Repeat the process for each frequency the SUT is to be calibrated. It is not necessary to get a
DVM reading across the bridge with the RF power off (V1) at each different frequency point. As
long as the Model 1825/1827 has been turned on for at least two hours, it should be thermally
stable and this value should not change during a calibration. Check V1 often during the first few
calibrations, and then determine how often it should be checked for the most time efficient and
accurate calibration possible.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
3-10
Theory of Operation
INSTRUMENT DESCRIPTION
PREPARATION FOR USE
OPERATING INSTRUCTIONS
THEORY OF OPERATION
SERVICE INFORMATION
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
4-1
Theory of Operation
Principle Of DC Substitution
The Model 1825 and 1827 use the principle of DC substitution to measure RF power. DC
substitution refers to the measurement of RF power according to the amount of DC power that
must be substituted for the RF power in a bolometer in order to cause equivalent thermal effects.
Since some of the RF power applied to the input of the power standard is lost by reflection and
other causes before it is applied to the thermistor element, the calibration factor of the standard
is applied by the following formula to determine the actual level of RF power:
PRF = Pdc
K2
Where:
PRF = Level of applied RF power,
Pdc = DC substituted power which is proportional to the applied RF power,
K2 = calibration factor of Model 1825/1827 traceable to NIST
Precision Power Measurement
The Model 1825 and 1827 RF Power Sensor Calibrators and a digital voltmeter with a 6½-digit
resolution combine to provide the precision power measurement system. This system features the
Model 1825/1827 closed-loop, self-balancing Type IV Bridge circuit consisting of two legs - a
precision resistance leg 200 ohms and a leg linked to a thermistor element in the Model
1825/1827 power standard. A thermistor is a type of bolometer whose resistance decreases as a
function of increasing heat associated with ambient temperature or applied power.
This system also features the Model 1825/1827 temperature control circuitry that temperature
stabilizes the thermistor element. This eliminates changes in the thermistor element's resistance
due to ambient temperature changes and thus isolates the causes of thermistor variation to the
application of RF and DC power only.
Self-Balancing Bridge Circuits
The Model 1825 and 1827 contain a bridge circuit that performs DC substitution. Figure 4.1 shows
a simplified schematic of the bridge circuit in the Model 1825 and 1827.
The self-balancing bridge circuit, in a closed-loop configuration, consists of two legs: a precision
resistance leg 200-ohm and a leg containing a thermistor element. The precision resistance leg
maintains a constant effective resistance value of 200 ohms. When the power standard is
temperature stabilized by the temperature control circuit, thermistor resistance varies solely due
to the application of RF and DC power.
Each leg uses an operational amplifier (U1 or U2) to sense voltage imbalances and to drive
transistors (Q1 and Q2) to correct them. The power supply assembly provides isolated ±15 volt
biasing to each op-amp. Since the voltage differential at the input stage of op amp U2 is
negligibly small, it provides a virtual common reference to op amp U1 (i.e., it acts as a virtual
common ground since the voltage approaches zero with respect to either ground). This forces the
current through the thermistor to equal the current through the precision resistance leg.
The application of RF power to the thermistor element creates a decrease in the voltage drop
across the thermistor element due to its negative temperature coefficient. This decreased voltage
drop, in turn, creates an unbalanced bridge condition. When resistance in the thermistor element
leg of the bridge changes due to the application of RF power, op amp U1 senses a voltage
difference between Va and Va' and causes Va' to equal Va. When Va' equals Va, the voltage across
the thermistor element leg equals the voltage across the precision resistance leg. Also, the closed
loop circuit configuration maintains equal current throughout the bridge. Since the voltage and
current throughout the circuit is equal, the resistance in both halves is also equal. Therefore,
when the thermistor mount's temperature is stabilized and RF power is applied, a change in
voltage across the precision resistance leg is proportional to the amount of RF power applied to
the thermistor element.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
4-2
Theory of Operation
VOLTMETER
RED
I
BLACK
200 Ω
+15 V
Va'
Q1
Vb'
U1
U2
Vb
Va
+15 V
Q2
I
T
RF IN
Figure 4.1 Simplified Schematic of the Model 1825/1827 Bridge Circuit
Power Measurements
The precision measurement system measures RF power in terms of a power change across the
precision resistance leg. A digital voltmeter measures voltage across the precision resistance leg
which can be used to determine the power by the following equation:
P = V2
200
Where:
P = power across the precision resistance leg
V = voltage measured across the precision resistance leg
200 = resistance value of precision resistance leg
The RF power introduced to the thermistor is directly proportional to the change in DC power
across the precision resistor. The change in DC power across the precision resistor leg is given
by:
ΔP = P1 – P2
Where:
ΔP = the change in power across the precision resistance leg when RF power is applied to the
thermistor leg,
P1 = power across the precision resistance leg without RF power applied,
P2 = power across the precision resistance leg with RF power applied
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
4-3
Theory of Operation
To determine the power across the precision resistance leg without RF power applied, measure
the voltage before the application of RF power (V1). To determine the power across the precision
resistance leg with RF power applied, measure the voltage during the application of RF power
(V2). Once these two voltage measurements are made, the power can be determined by using the
first equation. By substituting for P1 and P2 from the previous formula:
ΔP = (V1)2
200
Combining terms:
(V2)2
200
ΔP = (V1)2 - (V2)2
200
Where:
ΔP = the change in power across the precision resistance leg when RF power is applied to the
thermistor leg,
V1 = DVM reading across the bridge in the absence of RF power,
V2 = DVM reading across the bridge with RF power applied,
200 = nominal resistance of the 1825/1827 thermistor in Ohms,
Since the change in power across the precision resistor is DC power, ΔP is also represented as Pdc.
The change in DC power across the precision resistor is directly proportional to the RF power
introduced to the thermistor. Like all RF power sensors, some of the RF power applied to the input
of the Model 1825/1827’s power standard is lost by reflection and other causes before it is applied
to the thermistor element. Thus, calibration factors based on frequency are associated with the
Model 1825 and 1827 and are applied in the following formula to determine the actual level of RF
power:
PRF = Pdc
K2
Where:
PRF = Level of applied RF power,
Pdc = DC substituted power which is proportional to the applied RF power,
K2 = calibration factor of Model 1825 or 1827 traceable to NIST
Controlling Thermistor Temperature
The Model 1825 and 1827 contain a thermistor which is a temperature-sensitive device. In order
to provide precise measurements, the effects of changes in the ambient temperature upon the
thermistor must be eliminated or minimized. The Model 1825/1827 temperature controller
accomplishes this by raising the power standard’s internal temperature to a level higher than the
ambient temperature (approximately 60° C) and maintaining that level by controlling the current
applied to the power standard’s heater element. This prevents any thermistor imbalance due to
ambient temperature change. Therefore, all temperature changes are due to the application of RF
and DC power.
The temperature control circuit performs two basic functions: control the temperature of the
thermistor element and illuminate the READY LED when the power standard has reached its
operating temperature. Refer to Figure 4.2 for the following discussions concerning the
temperature control circuit. The Wheatstone Bridge composed of R1, R2, R3, and R4 is actually
wire wound around a thermal mass and not only heats the mass but also detects the temperature
of it. The wiring heats the mass to a temperature above the ambient temperature. The thermistor
beads are mounted on this thermal mass and insulation surrounds the assembly to improve
temperature stability. Two windings, represented as R1 and R2, of zero temperature coefficient
wire (manganin) make up two legs of the bridge. The remaining two bridge windings, R3 and R4,
have a positive temperature coefficient wire (nickel). When the operating temperature is reached,
the heater windings provide equal resistance and the bridge balances. The temperature is
determined such that the thermistor bead bias power is 30mW ± 0.7 mW.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
4-4
Theory of Operation
+20 V
R16
CR3
R4
R1
Q2
U2
R9
R2
Q3
U1
R3
R6
Q1
READY
Q4
Figure 4.2 Simplified Schematic of the Model 1825/1827 Heater Circuit
U1, a high-gain amplifier with excellent offset drift characteristics, senses imbalances across the
bridge. U1/U2 interaction provides a varying response to thermal bridge imbalances according to
the relationship between the voltage differential inputs. U1/U2 amplifies an imbalance signal from
a cold bridge that forces the series pass transistor Q3 to pass a current proportional to the
imbalance signal. This current drives the bridge to restore balance. As the bridge nears the
steady-state condition, Q3 causes the READY LED to illuminate. If the mount is cold, the READY
LED does not illuminate since the Darlington pair configuration made up by Q1 and Q4 is not in a
conducting state. U1/U2 responds to an imbalance signal from an overheated mount by turning
off Q3 so that it passes no current to the heater or READY LED. Transistor Q2 and Resistor R16
combine to provide circuit protection by limiting current in the event of an output short circuit.
Calculating Uncertainty
Measurement uncertainty when using the Model 1825 or 1827 can be calculated with the
following formula:
UP = √ UC2 + IE2 + MER2
Where:
UP = uncertainty of the power measurement of the Model 1825 or 1827,
UC = uncertainty of the cal factor for the Model 1825 or 1827 which is frequency dependent,
IE = the random part of the uncertainty of the instrumentation,
MER = mismatch error which is frequency dependent.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
4-5
Theory of Operation
Mismatch Uncertainty (MER)
Device mismatch is the term used to describe the differences in impedance between RF devices.
This difference in impedance causes some of the RF power to be reflected back from one device to
another; thus, not all applied RF power is transferred from one device to another. The amount of
power that is not transferred can be characterized as the reflection coefficient, or Γ. The reflection
coefficient for the Model 1825 and 1827 is included as part of the calibration data. Mismatch error
(MER) is determined from the reflection coefficients of both the Model 1825 or 1827 and the SUT
as follows:
1
MER = 1(1 ± |Γ1| x |Γ2|)2
Where:
MER = residual mismatch error,
Γ1 = reflection coefficient for the Model 1825,
Γ2 = reflection coefficient for the SUT.
Reflection Coefficient is a complex number expressed as a vector quantity. A vector quantity has
two components a magnitude and phase angle. The magnitude of the reflection coefficient is
symbolized by the Greek letter rho ρ and the phase angle by the Greek letter phi φ. Often, the
magnitude is the only part of the reflection coefficient used, which will yield a “worse case”
mismatch uncertainty. Sometimes the Standing Wave Ratio (SWR) of a device is given rather
than the reflection coefficient (Γ). SWR is a scalar quantity and related to ρ follows:
ρ= S-1
S+1
Where:
ρ = magnitude of the reflection coefficient,
S = Standing Wave Ratio (SWR).
Impedance mismatch between all devices connected to the SENSOR port of the 1825/1827 should
be included in MER. That means the reflection coefficient or VSWR of any adapter, attenuator, or
matching pad used should be known. To include these devices, use the equations above to
determine the mismatch uncertainty between each device that is connected together. MER is the
sum of those mismatch uncertainties.
Gamma Correction
If both the ρ and φ of the reflection coefficient are known for both the SUT and 1825/1827
(TEGAM provides this data as part of the calibration for the 1825/1827), then Gamma corrections
can be applied to the calibration factor of the SUT. Applying Gamma corrections to the calibration
factor reduces the total uncertainty of the calibration by eliminating MER. Gamma corrections are
applied to the SUT’s cal factor as follows:
K1S
Corrected K1S =
|1 + Γ1Γ2|2
Where:
Corrected K1S = cal factor of the SUT after Gamma correction are applied,
K1S = cal factor of the SUT before Gamma correction is applied,
Γ1 = reflection coefficient of the 1825 or 1827,
Γ2 = reflection coefficient of the SUT
That equation can be “simplified” to :
Corrected K1S =
K1S
(1 – ρ1ρ2 cos(φ1 + φ2))2 + (ρ1ρ2 sin(φ1 + φ2))2
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
4-6
Theory of Operation
Instrumentation Uncertainty (IE)
These uncertainties are limited by the quoted accuracies of the various equipment involved. Refer
to Table 4-1 for an analysis.
Table 4.1 A Typical Instrumentation Error Analysis (IE)
Item
Specified Accuracy
Effect on Uncertainty
Model 1825/1827
DC Substitution Bridge Accuracy
±0.003
±0.003%
Connector Repeatability
±0.1
±0.1%
Temperature drift
±0.05
±0.05%
Power Linearity (1 to 10 mW)
0 at 1mW
±0.1%
Calibration Factor Drift with
±0.5
±0.5%
Time
Total RSS Uncertainty
±0.51%
Other Instruments
Digital Voltmeter Accuracy
See manufacturer’s
specifications
Digital Voltmeter Nonlinearity
See manufacturer’s
specifications
Power Meter Accuracy
See manufacturer’s
specifications
It should be noted that the Model 1825 and 1827 are calibrated at 1 mW. If the transfer to the
SUT is also performed at 1 mW, then the Power Linearity has zero effect. Otherwise, to determine
Power Linearity, multiply the nominal power level by ±0.01% up to a nominal power level of 10
mW. From 10 to 25 mW, the additional Power Linearity becomes negligible.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
4-7
Service Information
INSTRUMENT DESCRIPTION
PREPARATION FOR USE
OPERATING INSTRUCTIONS
THEORY OF OPERATION
SERVICE INFORMATION
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
5-1
Service Information
Warranty:
TEGAM, Inc. warrants this product to be free from defects in material and workmanship for a
period of 1 year from the date of shipment. During this warranty period, if a product proves to be
defective, TEGAM, Inc., at its option, will either repair the defective product without charge for
parts and labor, or exchange any product that proves to be defective.
TEGAM, Inc. warrants the calibration of this product for a period of 1 year from date of shipment.
During this period, TEGAM, Inc. will recalibrate any product, which does not conform to the
published accuracy specifications.
In order to exercise this warranty, TEGAM, Inc., must be notified of the defective product before
the expiration of the warranty period. The customer shall be responsible for packaging and
shipping the product to the designated TEGAM service center with shipping charges prepaid.
TEGAM Inc. shall pay for the return of the product to the customer if the shipment is to a location
within the country in which the TEGAM service center is located. The customer shall be
responsible for paying all shipping, duties, taxes, and additional costs if the product is transported
to any other locations. Repaired products are warranted for the remaining balance of the original
warranty, or 90 days, whichever period is longer.
Warranty Limitations:
The TEGAM, Inc. warranty does not apply to defects resulting from unauthorized modification or
misuse of the product or any part. This warranty does not apply to fuses, batteries, or damage to
the instrument caused by battery leakage.
Statement of Calibration:
This instrument has been inspected and tested in accordance with specifications published by
TEGAM, Inc. The accuracy and calibration of this instrument are traceable to the National
Institute of Standards and Technology through equipment, which is calibrated at planned intervals
by comparison to certified standards maintained in the laboratories of TEGAM, Inc.
Contact Information:
TEGAM, INC.
10 TEGAM WAY
GENEVA, OHIO 44041
PH: 440.466.6100
FX: 440.466.6110
EMAIL: sales@tegam.com
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
5-2
Service Information
Changing the Power Fuse
Different fuses must be used for different power supplies:
For the standard 105-125 Vac power supply use a 0.8A Slo-Blo fuse.
For the optional 210-250 Vac power supply use a 0.5A Slo-Blo fuse.
AC INPUT POWER
FUSEGROUND
FLOAT
Figure 5.1 Location of the FUSE
The fuse is located between the AC INPUT POWER connector and the FLOAT/GROUND switch on
the rear panel as depicted in Figure 5.1. To replace the fuse, remove the fuse cap by inserting a
flat screwdriver into the slot in the cap and rotate about ¼ counter-clockwise. The cap and fuse
will spring out; replace the fuse. Align the tab on the fuse cap with the notch on the fuse housing,
push the cap and fuse into the housing, and turn the cap ¼ clockwise with a flat screwdriver to
lock the cap down.
Preparation for Repair or Calibration Service:
Once you have verified that the cause for the Model 1825 or 1827 malfunction cannot be solved
in the field and the need for repair and calibration service arises, contact TEGAM customer service
to obtain an RMA, (Returned Material Authorization), number. You can contact TEGAM customer
service via the TEGAM website, www.tegam.com or by calling 440.466.6100 OR 800.666.1010.
The RMA number is unique to your instrument and will help us identify your instrument and to
address the particular service request by you which is assigned to that RMA number. Of even
more importance is a detailed written description of the problem, which should be attached to the
instrument. Many times repair turnaround is unnecessarily delayed due to a lack of repair
instructions or lack of a detailed description of the problem.
The detailed problem description should include information such as measurement range, trigger
mode, type of components being tested, is the problem intermittent?, when is the problem most
frequent?, has anything changed since the last time the instrument was used?, etc. Any detailed
information provided to our technicians will assist them in identifying and correcting the problem
in the quickest possible manner. Use the Expedite Repair & Calibration form provided on the next
page to provide detailed symptoms of the instrument’s problem.
Once this information is prepared and sent with the instrument and RMA number to our service
department, we will do our part in making sure that you receive the best possible customer
service and turnaround time possible.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
5-3
Service Information
Expedite Repair & Calibration Form
Use this form to provide additional repair information and service instructions. The completion of
this form and including it with your instrument will expedite the processing and repair process.
Instrument Model #:
RMA#:
Serial
Number:
Technical Contact:
Company:
Phone Number:
Additional
Contact Info:
Repair Instructions:
Evaluation
Calibration Only
Repair Only
Repair & Calibration
A2LA Accredited
Calibration (Extra Charge)
Detailed Symptoms:
Include information such as measurement range, instrument settings, type of components being
tested, is the problem intermittent? When is the problem most frequent?, Has anything changed
with the application since the last time the instrument was used?, etc.
Model 1825 and 1827 RF Power Sensor Calibrator Instruction Manual
5-4
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