tma installlation training

7/28/2019 TMA Installlation Training

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PRIVATE AND CONFIDENTIAL

ANDREW CORPORATION 4/06

Installation

TMA and Bias Tee


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TMA Installation

Any orientation is ok

TMA is 100% sealed

Connect to the proper ports ANT port to antenna

BTS port to feeder

Separate ground cable?

Ground path exists throughcoaxial cable shield

Use ground wire if in doubt

Follow local practice

Smaller TMAs mount withband clamps, not brackets

Rear Bracket

Flat Washer + Split Lock Washer + Hex Nut

TMA Bracket

Hex Bolt + Flat Washer

Grounding Bolt

Cap Screw for TMA Bracket


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Bias Tee Installation Icebridge

Used with outdoor BTS, including some Lucent ModCell

Bias tee grounding is essential

ABT-DMDF-ADB is most appropriate version


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Bias Tee Installation Top Cap

Used on outdoor BTS, e.g., Alcatel & Nokia

Separate ground may not be necessary

ABT-DFDM-ADB typically used


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Bias Tee Installation Hatch Plate

Installed on end of feeder insideshelter

Replaces lightning arrestor

Grounding is important

Ensure no obstructions to DCcurrent are between bias tee andTMA

No -wave stubs

No RET bias tees

ABT-DMDF-ADB is best fit

Feeder normally ends with femaleconnector


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Bias Tee Installation BTS Cabinet

Used on many indoor cabinets Nokia, Ericsson, others

Surge arrestor recommended at hatch plate

Must be DC passing, such as APTDC series

ABT-DFDM-ADB is used when installed on cabinet port (female)


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Bias Tee Installation with Diplexer

Can be installed at either BTS cabinet

Ensure DC pass through the branch used

Ensure DC block in opposite diplexer branch Diplexer with integrated DC block

Attached external DC block

Disused bias tee with DC cable removed

Installed on diplexer common port is an option

No DC through diplexer blocking not needed

Never attempt to combine DC sources Result will be unpredictable

Can cause equipment damage

Bias tee

Bias tee

DC block


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Power Distribution Unit

Description & Operation

OEM Substitutes


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PDU Construction

Supply voltage depends on model

24 VDC (18-36 VDC)

(-)48 VDC (38-58 VDC)

Input is polarity protected

Output current capability is thesame for all, but normal windowdepends on model, each output

20 3 to 165 5 mA, single-band

175 5 to 312 11 mA, dual-band

PTC resettable fuse on each output

Triggers around 600-1000 mA

Recovers automatically in < 20 s

Single relay alarm output

TMA current outside of window

Supply voltage out of range

DC/DC converter failure


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PDU Front Panel

TMA current OK or alarm disabled

TMA current above or below window

Short circuit or output disabled


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PDU Connections

Alarm Interface pin-out iswith reference to the relayin its de-energized state

Normally open (NO)

terminal is open Normally closed (NC)

terminal is closed

This is the alarm state

Defaults to alarm state ifsupply power is lost

PDU energizes the relay toindicate no alarm

Bias Tee Harness graycable may also be yellow

Power Cable leads areboth black


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PDU Operation

DC OUTPUT dip switches turn output voltage on/off

UP to enable

MHA ALARM dip switches turn current monitoring on/off

DOWN to enable

TMA current out of window for duration > ~2 s activates alarm

Turns green LED off and red LED on

Relay output indicates alarm

Excessive current (> ~800 mA, short circuit) triggers PTC resistor

Relay output indicates alarm

Alarm, once activated, must be reset manually

Turn PDU off and back on

Or use MHA ALARM switch UP to reset DOWN to re-enable


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OEM integrated TMA support

PDU function is built into BTS orNode-B

Bias tees are often detachable

but available from OEM

Ericsson RBS-2206 shown here

TMA support is activated throughthe O&M interface

Procedure varies by BTS type

Compatible with Andrew TMAsbut some exceptions exist


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OEM integrated TMA support

Bias tees connect to a DC outlet panel using a short coax cable

Andrew bias tees can be used in place of OEM in most cases

Andrew offers cables to fit Ericsson and Nokia outlet panels

Ericsson RBS-2206 Nokia UltraSite


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Troubleshooting


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Troubleshooting - Basics

DC problems involve the supply voltage and current to the TMA

PDU alarm is an indication of a DC problem

Alarm from OEM TMA support may not be separable from RF alarms

An RF problem may not exist or may be undetected

Cause of problem can be in DC supply, PDU, bias tee, TMA, or in cablesand connections anywhere in the DC path

RF problems involve the uplink and downlink RF signals

Alarms, if any, are reported from the base station, not the PDU

VSWR alarms are detected at the TX frequencies

Issues with noise levels pertain to the RX frequencies

Cause of problem can be in the BTS, bias tee, TMA, or other RF path


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Troubleshooting DC Problems

Is there a PDU alarm indication?

MHA ALARM must be enabled to obtain alarm indication.

If the DC path was broken, alarms must be reset from latched state.

Green lights nearly always mean there is no DC problem.

Is the PDU the correct model for the TMA?

Are the MHA ALARM switches firmly enabled?

Disconnect the Bias Tee Harness and confirm red lights come on. If they dont,the PDU is defective.

Red lights can indicate a TMA failure or (more often) an open circuit.

Disconnect DC at the bias tee and verify 12 VDC at the cable end. Reconnect.

Disconnect the bias tee ANT port and verify 12 VDC at the port.

Check for any DC blocks in RF path, diplexer, RET devices, etc.

Measure the current in line with the disconnected RF path. TMA in alarm?

Is there a TMA on this feeder? Sweep and look for filter response.

Poorly attached RF connectors? Sweep may look ok even if no DC contact.


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Troubleshooting DC Problems (contd)

Are there fewer than six outputs in use?

Make sure DC OUTPUT and MHA ALARM switches are set as appropriate.

Check Bias Tee Harness color coding to verify used/unused as intended.

No lights indicate a short circuit.

Make sure the DC OUTPUT switches are enabled.

Disconnect DC at the bias tee and measure resistance from bias tee center pinto case. Should be very high or open circuit. Short circuit looks like 1-15 ohms.

High resistance through the bias tee suggests the short is in harness or PDU.

Disconnect the bias tee ANT port and measure resistance of the feeder. Short? Check for any DC shorts in RF path. wave stub (may be part of connector)?

Is there a TMA on this feeder? Sweep and look for filter response.

Is the TMA installed backwards? Will sweep ok but measure DC short.

Remove TMA and measure at BTS port. Short indicates defective TMA.

Remove the bias tee and measure resistance between DC and BTS ports.

Continuity indicates defective bias tee. (DC path was grounded by the BTS.)


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Troubleshooting RF Problems

Does the BTS indicate high VSWR?

Is the alarm threshold set too low?

15.5 dB return loss is a reasonable expectation with multiple elements in path.

Disconnect the bias tee BTS port and sweep through the bias tee with DC to TMA.

If all good, the problem is with the BTS or cabling. Crossed jumpers?

If RX return loss is much better than TX band, problem is on antenna side.Turning off PDU should result in poor RX band return loss.

Disconnect the bias tee ANT port and sweep the feeder. Examine the TX band.

If all good, the problem is with the bias tee.

Is the reflection high and flat with no visible filter response?

Poorly attached RF connectors?

Diplexer misconnected to opposite band port?

Feeder not connected or connected to wrong frequency antenna?

Do a DTF (Distance To Fault) sweep. Any problem with the feeder?

Remove TMA, terminate ANT port and sweep at BTS port. Replace if < 18 dB RL.


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Troubleshooting RF Problems (contd)

Does the BTS indicate a high noise floor?

Have necessary configuration changes, if any, been made?

BTS may need to be programmed with the higher RX path net gain.

Procedure varies with BTS type.

Should an attenuator be installed at the RX port of the BTS duplexer?

This is another way to adjust the net RX path gain which is sometimes used.

Is the attenuator the specified value?

Is the perceived problem an observation of unfamiliar performance statistics?

The data may be as expected.

The performance improvement of the TMA should be possible to validate bylooking at the appropriate parameters.


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Andrew Corporation is the foremost global supplier of one-stop,end-to-end radio frequency (RF) subsystem solutions.

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