Lynx Micro System User manual

INSTRUCTIONS
RADIORADIO
INTERFINTERFAACECE

Thank you for purchasing the Lynx Micro System.
IMPORTANT
Thefollowinginstructionshavebeenpreparedtoprovide
usersoftheLynxMicroCommunicationsSystemwiththe
necessary information to enable safe and correct use.
Please read this booklet carefully and take time to
familiariseyourselfwithyournewequipmentanditsmode
of operation before attempting to use it during flight.

CONTENTS
SECTION PAGE Nº
1 INTRODUCTION 1
2 SYSTEM CONFIGURATION 3
3 INSTALLATION 5
4 SPECIFICATION 7

1
INTRODUCTION
The Lynx Micro System has been specifically developed for use in
the high-noise environment of open-cockpit aviation where noise
attenuationandmicrophonenoisecancellationareprimaryconcerns.
The Lynx Micro System Radio Interface Unit is purposely designed
for use with Lynx Micro System Headsets and airband radio
transceivers, to provide pilots with all the facilities necessary for high
quality radio telephony.
The Interface Unit
The interface is manufactured utilising the latest techniques in
microcircuit design, and surface-mount component technology, to
produce an exceptionally compact unit (fig 1).
Developed specifically for use in close proximity to engine ignition
systems,theinterface electronics are designedtobevirtually immune
to electrical interference. All electronic component parts of the unit,
including the leads and connectors, are screened to prevent noise
from electromagnetic radiation.In addition to passive shielding, the
processorincludes dedicated electronics toactivelyfilter and remove
interference from the audio signals passing through the unit.
The unit uses very little electrical current, especially during stand-
by, and has no noticeable effect on headset battery life when used
with a Micro System Headset.
Radio Configuration
The Radio Interface is intended for direct connection to a hand-
portable radio and can be supplied to work with all common types of
radio transceiver.
FIG 1 RADIO INTERFACE UNIT
HEADSET SOCKET
P.T.T. SWITCH
P.T.T. INPUT HEADSET
SOCKET
RADIO
LEAD

1
2
Power Supply
One or two headsets can be connected to the interface using the
locking connector sockets built in to the unit (fig 1). To simplify
operation,theinterfacedrawsitspowerdirectlyfromtheselfcontained
Micro System Headset and does not require a separate battery.The
interface is switched on automatically, and is ready for use, once a
headset is connected.Some specialist Lynx headsets do not contain
an internal battery and can not be used with this interface unit.
Push-To-Transmit
In order to provide the greatest flexibility of operation the interface
unit is fitted with a built-in 'Push-To-Transmit' (P.T.T.) switch, and a
P.T.T.inputsocket to allow aseparateexternalswitchtobeconnected.
During the operation of a P.T.T. switch, one of the headset
microphones is opened, for radio transmission, and the microphone
of any additional headset is muted. In order to prevent unwanted
noise affecting the radio transmission only one headset is able to
transmit at a time.
The two headset connection sockets, on the interface unit, are
marked 'Pilot 1' and 'Pilot 2' in relation to the two P.T.T.switches.The
built-inswitchcontrols radiotransmissionsfroma headset connected
tothe 'Pilot 1'socket.Anexternalswitch controls radio transmissions
from a headset connected to the 'Pilot 2' socket.
A single headset can be used to transmit with either the built-in
switch or an external switch by selecting the appropriate headset
socket. Two headsets can be used with an external switch to allow
both headsets to transmit alternately.
FIG 2 OPTIONAL P.T.T. SWITCH

3
FIG 3 INTERFACE CONFIGURATION
RADIO
OPTIONAL
P.T.T. SWITCH
BUILT-IN
P.T.T.
SWITCH
INTERFACE UNIT

2
4
SYSTEM CONFIGURATION
The Lynx Micro System concept is intended to simplify considerably
the configuration and operation of radio interface equipment within
the open cockpit environment.
Solo Operation
For solo applications a single headset may be connected to either
headset socket on the unit depending on which P.T.T.switch is to be
used.Ifrequired the headset leadmay be extended,using anoptional
extension lead, to allow the unit to be conveniently located.
It is important to remember that the P.T.T. switch built into the unit
controls a headset connected to the 'Pilot 1' socket, and an external
P.T.T. switch controls a headset in the 'Pilot 2' socket. Always take
care when connecting a headset to ensure that the correct socket is
selected in relation to the required P.T.T. switch.
The headset connection to the unit should be bayonet locked, and
correct operation of the equipment should always be established, by
a radio check, before flight.
Dual Operation
For intercom and radio use, two headsets may be connected to the
unit with the option of an external P.T.T.switch.It is important to note
that the individual headsets must be correctly fitted to the unit in
relation to the relevant P.T.T. switch.
An external P.T.T.switch should be located in the aircraft in relation
to the relevant headset to avoid confusion during operation. If
necessarythe headset leadscan be extended byfitting anextension
lead to the unit.Depending on the application, it may be desirable to
fit either one or two headset extension leads to allow the unit to be
conveniently located.
Correctoperation ofthe equipment should beestablishedby aradio
check before flight, and again always make sure that the bayonet-
locks, on all of the connections to the unit, are properly engaged.
Radio Connection
The interface unit is normally fitted with a standard radio connector
whichwillconnectdirectlytomostavailabletransceivers.Theinterface
electronics,however, are alwaysconfigured to work with thespecific
make and model of radio specified when ordering the unit.
Beforeusinganinterface witharadio,itisimportant toestablishthat
the unit is correctly configured, as connecting and using an interface
which does not match the radio may damage the unit or the radio.
Hand-portable radios must bepoweredfromtheirown battery pack,
or an external power source, when used with the interface unit.
Antenna Connection
The antenna connected to a radio greatly affects the performance of
the radio, both during reception and transmission.
Whileitispossibletooperateahand-portableradio
in an aircraft using the short helical antenna, this
practice is not recommended.The fitting of a 1/4-
wave whip antenna to the aircraft effectively
increases the power of a radio, in comparison to
the helical antenna, and allows transmission and
reception over a much greater range.

5
INSTALLATION
The Radio Interface can be fitted permanently to an aircraft by screw
fixingorplastic ties.Alternatively,the unit can betemporarily mounted
during flight using tube clips or Velcro.
During installation it is important to ensure that the unit and leads
do not interfere in any way with the aircraft control systems. Fixing
holes to mount the unit, or holes for cable routing, must not be drilled
in any structural member of the airframe.
Depending on the type of aircraft a specialist or licensed engineer
maybe required bylawto fitthe equipment orinspectthe installation.
Screw Fitting
The interface has two threaded inserts built into the back of the unit
for mounting purposes.The threads accept M4 x 1.0 metric machine
screws and allow the body of the interface to be screwed directly to a
panel or bulkhead.
When mounting the unit using screw fasteners it is also important
to fit the locking washers:to prevent the screws working loose due to
vibration.
Velcro Attachment
As an alternative to screw fixing, the unit may be attached to a panel
or bulkhead using the Velcro pads supplied.
The two separate pads are adhesive-backed, and are easily fitted
to both the unit and a suitable flat surface. Before applying the pads
to the unit or aircraft, make sure that both the surfaces are clean and
dry and free from grease. Providing that good adhesive bonding is
achieved the Velcro pads offer a secure and flexible method of fixing.
FIG 4 TIE SADDLE FITTING
SCREW FASTENER
TIE SADDLE

3
6
PlasticTie Fitting
As an alternative to panel mounting it is also possible to fix the unit in
position using plastic ties and tie-saddles.This method of mounting
is useful to attach the unit to tubular structures and avoids the need
to drill fixing holes.
Suitable ties, tie-saddles and screw fasteners are supplied in the
fixing kit. In order to use the ties for mounting, the tie-saddles must
first be securely screwed in position on the back of the unit (fig 4).
Tube Clip Fitting
Theunit is also suppliedwith twotube clips,whichoffer an alternative
to the plastic tie method, for fixing to tubular structures.
The tube clips are only suitable for use with 25mm diameter tube
but do allow the unit to be easily fitted or removed.The clips should
be securely attached to the unit using the screws supplied (fig 5).
Cable Routing
Allcablesconnected to the interfaceshouldbecarefullyroutedaround
the airframe and attached in position using the cable ties supplied.
Avoid fitting the cables in close proximity to possible sources of
interference such as strobe lights or the aircraft antenna. Headset
extension leads should be fitted with the headset connecter in an
easily-accessiblelocation next totherelevant seat.TheexternalP.T.T.
switch and lead must be positioned in the aircraft, in relation to its
active headset, to avoid possible confusion during operation.
Always check after installation that the interface unit and leads do
not interfere in any way with the operation of the aircraft.
COUNTERSUNK
SCREW FASTENER
FIG 5 TUBE CLIP FITTING
TUBE CLIP

7
TECHNICAL INFORMATION
Unit size ................................ 40 x 35 x 95 millimetres
Fitting area required.......... 110 x 35 x 110 millimetres
Radio Lead length ......................................... 2 Metres
Stand-by power consumption.................. < 100 µ Amp
Transmit power consumption ................... < 30 mAmp
P.T.T. Input............................. Normally-Open Contact
SPECIFICATION
Technical information is provided in this section which may be useful
duringthe installationof the interfaceunit.Additional informationcan
be obtained directly from Lynx Avionics.
RadioType
Each interface is configured to work with a specific make and model
of radio transceiver;the individual radio type configuration is marked
on the back of each unit.
P.T.T. Input
Several types of 'Push-To-Transmit' switch are available from Lynx
for direct connection to the interface unit and for use in different
applications.Connectorsarealsoavailablewhichallow any 'Normally-
Open Contact' switch to be used to key a radio transmission.
Headset Extension Lead
Headset Extension Leads are available from Lynx for use with Micro
System Headsets.The leads are available in two-metre lengths, and
are fitted with one male connector and one female connector.
Radio Interference
The main cause of radio interference can usually be attributed to the
aircraft engine electrical system. High-tension ignition systems, and
strobelights,emit strong electromagneticsignals which arereceived
by the radio antenna and amplified along with the radio reception.
Micro System communication equipment is virtually immune to
interference from electromagnetic radiation, but can not prevent
interference being introduced into the system by the radio. When
using a radio in an aircraft there are several simple steps that can be
followed to minimise the problem of interference, and considerably
improve the quality of radio reception.
Mount the radio antenna as far away from the engine as possible
andavoid routingthe antenna leadclose to theengine.Fitthe engine
ignition leads with suppressors or suppressed plug caps as a matter
of course. If necessary screen the ignition leads using a braided
sleeve earthed to the airframe. Finally avoid fitting strobe lights and
their associated power leads near to the antenna and its lead.
©Copyright Lynx Avionics MCMXCVII All Rights Reserved

4
8
FIG 6 MOUNTING HOLE DIMENSIONS
17.5
17.5
18 18
55
M4 x 1.0
THREAD
ALL DIMENSIONS
IN MILLIMETRES