Boonton PIM 21 User Manual

User’s Manual

P 21

Portable Passive

Intermodulation

Test Set

Manual P/N 98405800B

1 / 2010

Taking performance to a new peak

User Manual

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Front Panel Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Accessories Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Purpose, Function and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Operation Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Pre Test Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

PIM Testing Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Advanced Features and Settings . . . . . . . . . . . . . . . . . . . . . . . . .19

Menu Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Default Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

External Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Version Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Types and Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Addendum - Data Acquisition Software . . . . . . . . . . . . . . . . . . . . .

2 | PIM 21 User’s Manual

Introduction

Welcome to the Users Manual for the PIM 21 Passive Intermodulation Test Set.

This manual is to inform operators of the PIM 21 of the following:

• Safety Warnings and Safe Operational Procedures

• Equipment purpose, Features and Functional description

• Front Panel controls

• Accessories Kit components

• Operation Procedure and Pre test checks

• PIM Testing procedures

• Advanced Features and Settings

• Maintenance and Support

• Specifications

Safety Warnings

Non Ionizing Radio Frequency Radiation Hazard

This device generates low level Radio Frequency (RF) energy under normal operation, and
should always be operated in accordance with local and national licensing laws. RF energy in
the 800 to 1,000 MHz and 1,800 to 2,200 Mhz regions with a total power no greater than 5
Watts or +37 dBm is present at the test port during testing.

The Test Port is to be terminated into a non radiating 50 ohm load to reduce the risk of RF ex­posure. Do not operate the “Test / RF On Off” switch on the Test Set if Test Port is open or load
is unknown.

Electric Shock Hazard

The device is supplied with an external 90 to 264 Volt AC power supply for internal battery
charging and general operation for extended periods.

The AC power supply is for indoor use only and is not water resistant, a shock hazard may exist
if operated in wet areas.

Never operate the Test Set with the AC power supply in damp, wet or rainy areas/conditions.

Prior to AC connection always inspect the power cord and case of power supply for damage. If
damage is observed do not use until inspected and repaired by an authorized electrical con­tractor.

Battery Explosion Hazard

The device contains an internal sealed lead acid battery for portable operation. An explosion
hazard may exist if the battery is incinerated, exposed to extreme temperature (>158°F or

3Boonton

Introduction

+70°C) or charged with excessive voltage. Prior to disposal,
the battery must be removed.

To reduce the hazard from overcharging never exceed the
maximum ‘Ext DC’ voltage of 16 Volts.

As an additional precaution, always remove BATT Fuse, prior
to storage for longer than 4 months.

Transportation Hazard

The device operates by using a transmitted RF Test signal,
which may interfere with navigation and other electronic
systems.

To eliminate the potential of this hazard always remove the
BATT Fuse, prior to transportation by aircraft or near any elec­tronic security systems.

Disclaimer

PIM 21 transmits two CW RF signals with a power of up to 2 W
each to measure passive intermodulation of components and
transmitting systems. PIM 21 test systems are strictly built fol­lowing customer’s instructions on these measurement frequen­cies. Wireless Telecom Group and its subsidiaries are under no
circumstances accountable for use of PIM 21 not conforming to
laws and regulations of national and local authorities. Customer
/ user bear the full responsibility and legal accountability to use
PIM 21 only in a lawful manner.

4 | PIM 21 User’s Manual

Front Panel Survey

All user controls and connections are made on the front panel of the Test Set.

Some of the control switches have multiple functions, which are explained in detail in the Ad­vanced Features and Settings section of this manual.

5Boonton

Packing Contents

Standard
Accessories Kit

The standard accessories kit provided with the PIM 21 Test Set contains 1 each of
the following items:

57500100A Test Cable
Type N(m) - N(m), 4m (13 ft)

56810400A Power Cord
2m (6 ft)

48000100A Connector Adaptor
⁄”(m) - N(f)

56811400A DC Charging Cable
for Car Accessory Socket

48400700A Power Supply
90 - 264 VAC / 12 VDC, 4 Amp

70047300A Accessories Pouch

95951301A Cable (6 ft) 95951201A RS232 to USB

Converter

95950301A Connector Adaptor
⁄”(f) - ⁄”(f)

95951401A Connector Adaptor
⁄ DIN(F) to N(F)

95950501A Connector Adaptor
N(f) - N(f)

95950101A Low P Cable Load
5 W, N(f) connector

95950401A Connector Adaptor
⁄”(f) - N(m)

6 | PIM 21 User’s Manual

Optional
Accessories kit

95950701A ZB-B11 Test Cable,
⁄”(m)-⁄”(m), 3m (10 ft)

Notes:

For performance and safety reasons use only original qualified components to replace dam­aged or missing accessory kit items.

Components in the accessories kit are intended for PIM 21 use only however, it is possible to
use the Low IM load, test cable and adaptors for other applications.

Under no circumstances should the Low power PIM sources be used for any other application.
They are designed only for use as a low power intermittent test source, which can be quickly
damaged if used on a continuous basis.

95951001A Torque Wrench
18 ft-lbs

7Boonton

Purpose, Function and Features

Purpose, Function
and Features

Purpose

The PIM 21 is a portable test instrument for the detection of non-linear components and as­semblies in radio base station installations.

Non-linear Radio Frequency (RF) assemblies cause Intermodulation Distortion (IM) and the
purpose of the Test Set is to specifically test for this distortion in passive components.

Components such as coax feeder assemblies, filters and antennas all fall into this passive
category, the common term to describe this distortion is Passive Intermodulation Distortion or
PIM.

This tester is designed to aid communications technicians in the field locate components and
assemblies which are creating PIM and degrading the performance of the installation.

The PIM 21 is not intended to be a laboratory instrument or replace such instruments. It has
been specifically designed for field portability and fault location.

Effects Of PIM

A non-linear transfer function is deliberately created in some devices such as mixers. When
two RF frequencies are applied to a mixer other frequencies or products are created. It is the
creation of these additional products which can cause problems in radio base station installa­tions. For example, if the products of two transmitters fall on a receive frequency used at that
installation blocking may occur.

Measurement Theory
All passive RF components have some degree of non-linearity and the function of the PIM 21 is
to evaluate the amount.

Measurement of Passive Intermodulation distortion is typically performed with two excitation
frequencies (RF carriers) and a receiver tuned to the 3rd order IM product.

The frequency of the 3rd order product(s) can be calculated by the following:

IM3 = (2 x F1) – F2 or (2 x F2) – F1

Where IM3 = 3rd order product
F1 = First carrier frequency
F2 = Second carrier frequency

Results can be reported as absolute power measurement (-dBm) from the 3rd order receiver or
as a difference between the excitation carrier power and the receiver measured power (-dBc).

For all test cases the excitation carrier powers must be noted as this will affect the measured
PIM result.

8 | PIM 21 User’s Manual

The PIM 21 is a low power tester with excitation carrier powers up to +30/+33* dBm each. Its
minimum size, reliability, and battery operation, all provide true portability.

To test individual components, bench PIM test systems typically use a power of up to 20W per
carrier. Such systems are heavy and bulky, and are generally considered impractical for field
testing, especially at the mast head.

Measurements between 20W bench sets and 2W portable field sets show predictably some
what different readings. This does not at all diminish the value of the low power measurement.

In theory, a 3rd order IM product will increase by 3 dB for every 1 dB increase in carrier power,
however in practice increases are very much dependent on test conditions and are considerably
lower than the theoretical 3 dB per 1 dB change in power. This is believed to be due to the fact
that poor or corroded connections act much like a diode, and become abruptly non-linear when
sufficient current excites them. This current is usually very low so the PIM 21’s output power is
usually adequate.

The following chart shows 1W and 2W measurement results compared with the result seen
on a 20W bench tester for the same component. There is only a 10 dB difference between PIM
measured at 2W and 20W. The arrows on the chart that follows indicate that a -153 dBc 2
Watt measurement is the equivalent to a -143 dBc at 20W.

Many tests have been performed and results show that a good rule of thumb is about 10 dB. It
should be noted that in certain circumstances the difference could be as much as 20 dB.

Users in the field have found that system components such as antennas and feeder cables
generally do fail PIM with an abrupt change in PIM performance and the 10 dB rule of thumb
holds. A measured PIM below -140 dBc (Green LED’s) is a passing component, while a compo­nent measuring PIM above -140 dBc (Red LED’s) indicated a problem. This allows identification
of problem components with the PIM 21, in spite of the lesser sensitivity.

*Model Dependent

9Boonton

Purpose, Function and Features

-80.00

-90.00

-100.00

-110.00

-120.00

-130.00

-140.00

-150.00

-160.00

PIM adjustment chart 1W & 2W vs 20W

20 Watt Ref PIM -dBc

1 Watt equivalent PIM -dBc

2Watt equivalent PIM -dBc

PIM Measurement

PIM comparison for different carrier powers

Functional Description

The PIM 21 generates two continuous wave carriers at up to 1W / 2W each*. These two carriers
are filtered and combined to a single common test port. The frequencies set in the PIM Test Set
depend on the type and can be customized. For references, please see the table in the adden­dum.

A receiver is also connected to the common test port via another filter. The receiver is tuned to
the 3rd order Intermodulation product of the two carriers for the measurement of PIM.

Receiver sensitivity is better than -123 dBm, typically -126 dBm.

Functional Block diagram

A microprocessor is used to monitor and control all active modules within the tester. Calibra­tion tables are stored in non-volatile memory for all critical RF functions i.e. Rx calibration
parameters and excitation carrier power.

* Model Dependent

10 | PIM 21 User’s Manual