mcmurdo S4 Rescue SART User manual

S4 RESCUE SART
Service
Service Service
Service Manual
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S4 RESCUE SART service manual Issue 2
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Contents
1. Introduction........................................................................................................................... 1
1.1. Scope ............................................................................................................................. 1
1.2. Applicability..................................................................................................................... 1
1.3. Revision history .............................................................................................................. 1
1.4. Servicing equipment ....................................................................................................... 2
1.5. Safety notices ................................................................................................................. 3
2. Assessment .......................................................................................................................... 5
2.1. Maintenance tas s.......................................................................................................... 5
2.2. Routine testing................................................................................................................ 5
2.3. Assessment .................................................................................................................... 5
3. Maintenance rocedures ..................................................................................................... 8
3.1. Mechanical inspection .................................................................................................... 8
3.2. Self test procedure ......................................................................................................... 8
3.3. Functional testing ........................................................................................................... 9
3.4. Frequency testing ........................................................................................................... 9
3.5. Lea testing .................................................................................................................. 12
3.6. Battery replacement ..................................................................................................... 13
4. Fault finding ........................................................................................................................ 17
5. Re air rocedures.............................................................................................................. 18
5.1. Replace O-ring ............................................................................................................. 18
5.2. Replace PCB ................................................................................................................ 18
5.3. Re-tune PCB ................................................................................................................ 19
5.4. Factory return procedure .............................................................................................. 19
6. S ares.................................................................................................................................. 20
A endix 1: S ecification ......................................................................................................... 21
7. Product Warranty ............................................................................................................... 22
8. End of Life Statement......................................................................................................... 23
8.1. Battery Removal ........................................................................................................... 23
8.2. Disposal........................................................................................................................ 23
This document is McMurdo copyright (©) and contains proprietary owned intellectual property rights and confidential data. All
rights are strictly reserved. The information must not be used except for the agreed purpose. Unauthorized use, reproduction
or issue to any third party is not permitted without the prior written authority of McMurdo. This document is to be returned to
McMurdo when the agreed purpose is fulfilled.

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1. INTRODUCTION
The Search and Rescue Radar Transponder (SART) is a rescue aid designed to detect an X-
band marine radar signal and produce a distinctive radar return pulse which causes a series of
radial dots to appear on the remote radar screen. These dots are recognised as a “distress”
pattern and assist in the location of the SART.
The SART wor s with any radar operating between 9.2 and 9.5GHz. It has a broadband receiver
that detects any incoming radar pulse and “triggers” the SART. Once triggered, the SART
switches to transmit mode and responds with 12 sweeps across the entire 9.2 to 9.5 GHz radar
band. At some point in each sweep the frequency will “hit” the radar’s receiver band and produce
a simulated 'echo'. A total of 12 'echoes' are produced as a radial line on the radar screen, the
innermost 'echo' being the approximate position of the SART.
The SART has four modes of operation:
Off – all functions are disabled. This is the storage condition.
Slee – the receiver is active and ready to respond to a detected signal.
Standby – the receiver and transmitter are active and ready to respond to a detected signal.
Transmit – a signal has been detected and the unit is responding.
Upon switch on, most units will immediately be in Standby mode; after approx 15 – 18 seconds of
seeing no incoming radar pulses the SART will revert to sleep mode to save power.
1.1. Sco e
This manual represents the original equipment manufacturer’s (OEM) documentation applicable
to the SART equipment listed below. The manual provides complete instructions for shore-based
maintenance (SBM) providers to enable routine servicing of these products.
1.2. A licability
This information applies to the following SART models. All of these are “badged” versions of the
basic S4 SART.
• McMurdo S4 RESCUE
• SAILOR SART II
• SKANTI SART II
• RFD S4 RESCUE
Each SART version may be supplied as one of three options:
SART with pole and bul head mount
SART with pole only
SART only
1.3. Revision history
The S4 was introduced in 2003.
There have been no product revisions up to December 2004.

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1.4. Servicing equi ment
Detailed SART servicing requires specialist equipment, including a microwave pulse generator
and a spectrum analyser. To reduce equipment costs a dedicated SART tester (ARG 5420) is
now available. Traditionally this equipment is beyond the reach of many service agents and a
lower level of routine SART servicing has become normal. This just requires access to a marine
X-band radar to trigger the SART and view its response on the radar screen. For many service
agents located near a harbour this facility can be arranged with local boat owners. The level of
equipment required can thus be bro en into two categories:
Equi ment for advanced servicing:
a) 9.4 GHz pulse generator with suitable horn antenna
10 GHz minimum spectrum analyser (accurate to 1 MHz) with Rx antenna
or
b) ARG 5420 dedicated SART tester
Equi ment for routine servicing:
Marine X-band Radar within 3 miles (or access to this)
Lea test facility (made on site as required)
Static safe wor area with operator wrist strap
Battery discharge circuit (made on site as required)
Tin can or metallic cover for screening SART radome
Multimeter
Handtools:
Small Pozidriv (PT0) screwdriver
Large Pozidriv (PT2) screwdriver
Torque driver with 2mm hex (allen) bit
Antistatic recautions
The electronics section of the SART is sensitive to electrostatic discharge (ESD). ESD can cause
immediate or hidden long term damage. It is important that the PCBs are only handled under
suitable antistatic conditions.
Ideally, a fully grounded wor station which has conductive surfaces to avoid the build up of static
charge should be used. As a minimum, the operator must be connected to a good earth point
through a resistance of 1Mohm. This is usually achieved by wearing a suitable wrist strap.

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1.5. Safety notices
Please read the following for your safety:
This product has been assessed as presenting negligible hazard in a sealed serviceable state.
Safety analysis
The following table summarises the nature of the hazard which may be present when the unit is
opened or serviced; each hazard is discussed at greater length in the detailed sections.
Hazard cause Hazard identification Precautions
Lithium battery Explosive ris , corrosive fumes,
fire, biological hazard
Handle appropriately, avoid
contact
Radio frequency
radiation
Physiological hazard Avoid close or prolonged
exposure
IPA Irritant, highly flammable Avoid contact, ventilate well
Lithium batteries
Hazardous chemicals Wear gloves
The batteries used in these products contain Lithium (Li). Lithium is inflammable, reacts violently
with water and constitutes a biological hazard. These batteries are HAZARDOUS if short-
circuited, punctured, incinerated or deformed.
Lithium batteries must not be short circuited.
Lithium batteries must be handled, transported and disposed of using appropriate safety
precautions. The use of rubber gloves as a routine precaution is recommended.
In the event of lea age of the battery electrolyte (which can be recognised by a pungent odour),
ta e care to avoid contact, particularly with open wounds; do not ingest the material. Do not
attempt to discharge a lea ing battery – remove it using appropriate handling materials and seal
in a plastic bag, then dispose of it through an approved environmental disposal agent, or in
accordance with local regulations.
Radio frequency radiation
Radio frequency radiation
A SART produces microwave radiation when it responds to a radar. The radiated level is below
2W with a duty cycle below 1%. The low duty cycle means this is not considered to be a hazard.
During SART testing, ensure compliance with Health & Safety instructions when wor ing in close
proximity to the ship’s radar.

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General recautions for chemical agents (adhesives, greases, IPA)
Observe all safety precautions relevant to the country of operation. As a general rule, protective
overalls, gloves and goggles should be worn when handling these chemical agents, but different
countries may have additional requirements which must be observed.
Ensure that all chemical agents are handled in accordance with the manufacturer's instructions,
and that suitable protective clothing is worn.
Ma e sure that the wor ing area is well ventilated, and that chemical substances are not left
exposed. Observe good hygiene practices; do not eat, drin or smo e when handling chemicals.
Cyanoacrylate adhesives bond instantly on contact. If s in is bonded, it can usually be released
by a gentle peeling action; above all, do not panic and avoid direct pulling on bonded s in.
Read the manufacturer's instructions before using any chemical agent.
Wear goggles Wear overalls Wash hands Wear gloves

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2. ASSESSMENT
2.1. Maintenance tasks
Service agents (Shore Based Maintenance (SBM) providers) are reminded that it is their
responsibility to ensure that good common practice and the procedures herein are followed and
that only McMurdo approved parts are fitted.
Routine service agents can provide:
• Assessment
• Functional test
• Lea test
• Battery replacement
Advanced service agents can also provide:
• Microwave testing
• Frequency adjustment
2.2. Routine testing
Every SART should be tested monthly by its owner to ensure its functionality.
Whenever possible the SART should be inspected for mechanical damage.
It is strongly recommended that the SART be functionally tested every year using a radar signal.
The SART should not be opened during this test. An approved service label showing the date of
test should be affixed to the outside of the SART.
Every time the batteries are replaced, the SART must receive a functional test and a lea test, as
shown in the table below.
Frequency of testing:
INTERVAL PERFORMED BY
Self test Function test Leak test
1 month  Customer
1 year   Customer or SBM provider
Battery change    SBM provider
2.3. Assessment
Every SART returned for servicing, of whatever nature, must be fully assessed to determine its
operational status. The diagram shows the tas s which must be carried out for each servicing
situation. This must include a functional test and a lea test.

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Assessment form
The assessment form overleaf serves as a prompt to ensure no assessment steps are left out. It
may be used to support customer billing, and must accompany any warranty return to the
manufacturer.
It is important that as much information as possible is recorded on the form. Procedures for the
assessment are detailed in section 3.
ASSESSMENT
Inspect
Self test
Receipt
Functional test
Return
No fault
Lea test
Disassemble
Change
battery
Reassemble
Disassemble
Repair
Reassemble
Battery change Fault found
Lea test

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S4 SART ASSESSMENT Ref No.
Serial No.
Customer/Comments Date.
Ins ection Remarks
Casing intact YES NO
Pole intact YES NO
Pole extends correctly YES NO
Lanyard OK YES NO
Frangible tab intact YES NO
Battery expiry date OK YES NO Date:
Self test
Un-triggered (sleep) state PASS FAIL
Triggered (active) state PASS FAIL
Functional test PASS FAIL
Frequency test results
Upper frequency
(9.53±0.03 MHz)
PASS FAIL Value: MHz
Lower frequency
(9.17±0.03 MHz)
PASS FAIL Value: MHz
Number of sweeps
(12±1)
PASS FAIL Value: sweeps
Pulse length
(95±13 us)
PASS FAIL Value: us
Battery voltage PASS FAIL Value: volts
Leak test (if opened) PASS FAIL
Date Name of tester Signature
Conclusions
Parts
required:
Brac et 
Pole 
Frangible tab 
Radome 
Battery it 
PCB module 
Spring 
Sealing it 
Other

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3. MAINTENANCE PROCEDURES
3.1. Mechanical ins ection
Casing Ensure there are no visible crac s or mechanical damage.
A crac ed casing will lead to water ingress and is a serious fault.
Pole Confirm the pole is intact and in good condition. The pole
should be chec ed by removing the cap from the bottom of the pole tube
and chec ing that the sections can be extended smoothly, and that they
loc into position. Ensure that the pole is fully stowed after inspection, and
that the end cap is secure.
Lanyard The lanyard must be fully wound on the spool, such that only the ball
at the end is outside the casing.
Frangible tab A bro en frangible tab means that the SART may have been activated.
If this is the case, fit a new battery.
Battery expiry Note the expiry date. If there is less than 6 months left contact
vessel and advise that they will need a new battery.
3.2. Self test rocedure
CAUTION: Only test for the minimum time possible.
A live distress call may be received by other vessels within range.
Equi ment
Testing requires a signal to trigger the SART out of sleep and into active/standby mode.
This can be supplied by :-
• An X-band marine radar operating nearby (within 3 miles)
• A dedicated SART tester (ARG 5420)
• A 9.35 GHz microwave pulse generator, set for 1 us pulse every 1 ms.
In addition, to prove that the SART returns to sleep mode, the signal must either be turned off
(SART tester or pulse generator) or the SART upper section (radome) can be covered with a
metal container – a can of suitable size wor s well.
Test rocedure
1. Turn trigger signal off or cover radome with can
2. Rotate the switch ring to TEST
Indicator
light
TEST

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3. Confirm SART indicates sleep mode as per table below
Slee Standby/Transmit
LED flashes every 2 seconds
Beeper off
LED is on continuously
Beeper sounds every 2 seconds
4. Turn trigger signal on, or uncover radome, chec transmit is indicated
(see above)
5. Turn trigger signal off or cover radome. Confirm that sleep indication returns.
Note: A delay of 20 seconds is normal after signal is removed
6. Release switch ring; chec it returns to ‘O’
NOTE: Without specialised equipment, it is not possible to differentiate between Standby and
Transmit modes.
3.3. Functional testing
CAUTION: Only test for the minimum time possible.
A live distress call may be received by other vessels within range.
This test involves observing SART transmissions and can be done two ways:
• Using a dedicated SART tester (ARG 5420). See section 3.4.
• Using a nearby radar and observing the radar screen (explained here).
Procedure
1. Locate SART as far from radar as is practical. A minimum of 20 m is advised.
2. Activate SART in self-test mode. See section 3.2 for details.
3. Hold SART upright so that it has line of sight to the radar antenna.
4. The SART should indicate “active” mode.
5. Confirm the radar screen shows typical SART echoes.
6. De-activate the SART as quic ly as possible.
Observations
The SART response is a series of 12 pulses, which is displayed on a radar as a number of
echoes spaced approximately 0.6 nautical miles apart. Ideally, these will be clear dots extending
radially outwards, However, close proximity to the radar may result in circular blurring of the
display – in extreme cases, a series of concentric circles may be produced. This is quite normal
at close proximity and still constitutes a PASS for the functional test.
3.4. Frequency testing
Frequency testing is included here as an o tional maintenance procedure. It is not required
during routine servicing. However, some countries do require testing of the SART frequency
sweep limits, in which case this section will be helpful.
To measure the frequency sweep, the SART must be continuously triggered with a suitable
microwave signal. The 12 response sweeps are then viewed using either:
a) 9.4 GHz pulse generator with suitable horn antenna
10 GHz spectrum analyser (accurate to 1 MHz) with Rx antenna
b) ARG 5420 dedicated SART tester
Method (a) requires complex configuration and is left to the specialist service agent.
Method (b) using the SART tester is simple and is described below.

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ARG 5420 SART tester
The Sartech/ARG 5420 portable SART tester is a hand-held instrument which triggers a SART
and measures the resulting response. The frequency spectrum, frequency limits, pulse length
and number of sweeps are measured and displayed. Test results may be stored for later recall or
they may be printed.
Procedure
Comprehensive instructions are given in the handboo provided with the equipment; this
summary only acts as a reminder to users who are familiar with the instrument.
1. Switch on 5420 and chec display.
2. Press F4, press F1 twice.
3. Activate SART in Self-test mode.
4. Hold 5420 horizontal, about 300 mm (12") from top of SART.
5. Press and hold F1 on 5420 until a consistent spectrum is displayed.
6. De-activate SART.
7. Press F3 twice on 5420 to display PASS/FAIL listing.
8. Press F3 again, then F2 to save the result.
9. Press F4, then enter the SART serial number.
10. Press F4 to store.
Alignment of ARG5420 with SART
At close range the signal from the SART is directional. Best results will be obtained when the
tester is positioned as shown. It may be necessary to rotate the SART to find the best signal
strength.
ARG5420
SART being
tested
300mm (12") approx

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SART tester features
The SART tester displays the results of the tests in three ways:
1. During and after the test, it displays the response as a graph of amplitude against frequency
– the ‘spectrum analyser’ display. The position of the tester should be adjusted to produce
the optimum response – it is desirable to receive the greatest possible strength of signal, but
not to saturate the 5420 receiver.
Spectrum analyser display
2. Once the test is complete, pressing F3 on the tester displays the frequency response of the
SART against time, and so shows a series of frequency sweeps. A magnified view (press F1)
is shown – note that the SART being displayed sweeps down from 9.5 GHz to 9.2 GHz. Note
the exact limits of the frequency sweep – 9.53 and 9.16 GHz – are displayed on this and the
next screen.
Sweep frequency display
3. Pressing F3 again displays the summary results with the PASS/WARN/FAIL classification.
Summary results

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3.5. Leak testing
Two alternative methods of lea testing are given. The gross lea test is preferred, as it causes a
greater pressure differential across the seals of the SART, and so is more li ely to detect a lea .
Also, as this is a “positive pressure” test, there is less ris of a lea ing SART filling with water.
If the immersion test is used, the accuracy and repeatability of the weighing scales is critical. A
SART weighs approximately 0.5 g and the pass criterion is a weight gain of less than 1 g, hence
a repeatability of better than 0.1% is essential.
The SART floats, so it must be constrained to ensure that it stays submerged.
Gross leak test
CAUTION: Hot water. Ta e appropriate protection measures.
1. Immerse the SART in hot water: the ideal temperature is
60º ±5 ºC; cooler water will not cause a sufficient rise in
temperature, hotter water may damage the SART.
2. Dislodge all trapped air from the sealing ring mouldings, the mast stowage fitting and
the actuation switch area.
3. For the next five minutes, while eeping the SART submerged chec for the escape
of bubbles, particularly from the sealing flanges and around the switch actuation
apertures.
4. Remove the SART from the water and dry it thoroughly before its temperature drops.
Provided that the water is clean and fresh, no damage should be sustained from a lea . Lea ing
SARTs may be disassembled and dried in an oven (maximum 55 ºC), then re-assembled and re-
tested.
Any escape of bubbles must be considered a failure. If the unit fails then disassemble the SART.
If there is any evidence that water has entered the battery pac then it must be replaced. To
rectify the lea , it may be necessary to replace the ‘O’-ring.
Immersion ressure test
This test chec s for a gain in weight caused by the ingress of water.
1. Weigh the SART on an accurate scale and record the value.
2. Immerse the SART in cold clean fresh water, as deep as possible.
3. Keep the SART submerged for at least 12 hours.
4. Remove the SART from the water and dry it out thoroughly (water trapped in the
lanyard will cause errors).
Re-weigh it on the same scale as used previously.
A gain in weight in excess of 1.0 g indicates a lea .
Provided that the water is clean and fresh, no damage should be sustained from a lea . Lea ing
SARTs may be disassembled and dried in an oven (maximum 55 ºC), then re-assembled and re-
tested.
Any escape of bubbles must be considered a failure. If the unit fails then disassemble the SART.
If there is any evidence that water has entered the battery pac then it must be replaced. To
rectify the lea , it may be necessary to replace the ‘O’-ring.
Hot

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3.6. Battery re lacement
It is essential for safety and the reliability of the equipment that only the correct type of battery is
fitted. Use only McMurdo approved parts.
All batteries carry a label showing the replacement battery part number.
Battery voltage test
Lithium batteries have a very constant discharge voltage over time, hence voltage is not any
indication of the capacity remaining in the battery. The only test which can be applied is to
measure if this plateau voltage has been reached (as it is slightly lower than the fresh battery
voltage) and to assume that the life of the battery has been compromised if this plateau voltage
has been reached.
There are two separate supplies from the battery, hence there are two voltages to measure. The
open-circuit voltages must be 10.8 V or greater and 5.4 V or greater, otherwise the battery must
be replaced. Voltages should not be measured within 5 minutes following activation or self-test.
The it contains the following parts :-
Battery pac assembly 86-430
O ring 86-425
Screw M4 x 30 SS PH Pozi x3 86-412
Screw M4 x 60 SS PH Pozi x1 86-413
Frangible tab 86-436
Batteries contain hazardous material and must be handled and disposed of
in accordance with local regulations.
Re lacement rocedure
CAUTION: Before underta ing any wor , Service Agents are advised to carry out an inspection
of the SART to ensure that it is in a suitable condition to be returned to service after the battery
change.
Remove the three screws visible when viewing the underside of the SART. When the pole
brac et is fitted, its retaining screw is longer than the other two screws; when no brac et is fitted,
all screws are the same length. Discard the removed screws. Remove the pole brac et if fitted.

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Remove the lower section of the SART by roc ing it gently from side to side until the three
battery connectors disengage.
Discard the complete battery section including the frangible tab. Ta e care to dispose of the
battery in accordance with applicable regulations.
Carefully pull off the switch actuation ring, ta ing care not to lose or damage the spring. Inspect
the ring to ensure that the magnet is in position.
Remove and discard the O-ring from the SART body. Do NOT use sharp tools; the
recommended method is to squeeze the O-ring between thumb and forefinger and push it until it
bulges clear of the groove (as shown above right), then to pull that part clear of the groove.
Fit the new O-ring to the SART body.

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Reassemble the switch ring and fit the spring according to the drawings below, ensuring that the
spring lies flat in the housing.
Fit the frangible tab as shown.
Fit the replacement battery section. Line up the switch ring groove with ‘O’, align the frangible tab
with this groove and ensure that the battery connectors are aligned. Push the two major parts
together.
Refit the pole brac et if applicable.
Fit the appropriate three screws and tighten to a torque of 1 Nm (100 cNm).
The SART is now fully assembled. Before it can be returned to service, it must be chec ed for
integrity and performance. Ensure that the SART is watertight by carrying out a lea test - refer to
Section 3.5. Perform a self-test.

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Dis osal of batteries
Hazardous chemicals Wear gloves
Lithium battery pac s should be discharged slowly, then disposed of through an approved
environmental disposal agent, or in accordance with local regulations.
The rate of discharge must not exceed 100 mA. Resistors of 68 ohms (for the 6 V nominal
output) and 150 ohms (2 W rating) are satisfactory for the SART battery. UNDER NO
CIRCUMSTANCE MAY THE BATTERY BE SHORT-CIRCUITED.
If the battery shows signs of electrolyte lea age, do not attempt to discharge. Refer to section 1.5
for advice on correct handling.

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4. FAULT FINDING
Due to the nature of the SART fault finding is limited. The steps shown below should be sufficient
to trace the fault to a major sub-assembly, which can then be replaced.
The sequence given below requires that each part is completed satisfactorily before proceeding
to the next part. It is, for example, assumed that any faults found at a particular stage are
remedied before continuing.
The following table is applicable to all versions of SART.
Fault Cause Action
Dead battery Chec battery volts
Displaced magnet Chec switch ring
Red LED never on
Faulty PCB Replace PCB
SART in active mode Remove input signal No standby mode indication
Stuc in active mode Replace PCB
No active mode indication
when SART triggered
Faulty PCB Replace PCB
LED indicates active mode
But beeper does not sound
Faulty PCB Replace PCB
Drift on PCB Retune PCB Frequency limits wrong
Faulty PCB Replace PCB