Technisonic Industries Limited TFM-556 User manual

VHF High/VHF Low/UHF
MULTI-BAND FM
AIRBORNE TRANSCEIVER
MODEL TFM-556
Installation and
Operating Instructions
Til Document No.
03RE328
Rev. n/c
September 2003
Technisonic Industries Limited
240 Traders Boulevard, Mississauga, Ontario L4Z 1W7
Tel:[phone] Fax:[phone]
www.til.ca

CAUTION
This unit contains static sensitive devices. Wear a grounded wrist strap and/or conductive gloves when
handling printed circuit boards.
NOTE:
This equipment has been tested and found to comply with the limits for
a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are
designed to provide reasonable protection against harmful interference when
the equipment is operated in a commercial environment. This equipment
generates, uses, and can radiate radio frequency energy and, if not installed
and used in accordance with the instruction manual, may cause harmful
interference to radio communications. Operation of this equipment in a
residential area is likely to cause harmful interference in which case the user
will be required to correct the interference at his own expense.
Warning:
Changes or modifications not expressly approved by Technisonic Industries could void
the user’s authority to operate the equipment.
Important:
The TFM-556 transceiver is designed for airborne use. It is certified by Industry Canada under
aeronautical standard RSS 141 as amended. The equipment is not permitted to be installed in a fixed
or mobile, land based station in Canada.
WARRANTY INFORMATION
The Model TFM-556, Transceiver is under warranty for one year from date of purchase. Failed units
caused by defective parts, or workmanship should be returned to:
Technisonic Industries Limited
240 Traders Boulevard
Mississauga,
Ontario L4Z 1W7
Tel: [phone] Fax: [phone]
A Page

Summary of DO-160C Environmental Testing for Technisonic Model TFM-556, Low-band VHF, High-
band VHF and UHF Transceiver:
Conditions Section Description of Conducted Tests
Temperature and Altitude 4.0 Equipment tested to categories B2 and
D1.
Vibration 8.0 Equipment is tested without shock
mounts to categories B, M and N.
Magnetic Effect 15.0 Equipment is class A.
Power Input 16.0 Equipment tested to category B.
Voltage Spike 17.0 Equipment tested to category B.
RF Emission 21.0 Equipment tested to category Z.
Installation Approval Note
Presently no TSO standard exists for airborne FM transceivers. To make it easier for installation
agencies to provide their customers with an approved installation supported by an effective
Airworthiness Approval, Technisonic has secured Supplemental Type Certificate (STC) Approvals (both
US and Canadian) on its Airborne FM products for many helicopters currently being delivered in the
US and Canada as well as a number of single engine fixed wing aircraft. The above referenced DO-
160C test data is also on file and available from Technisonic to support approval requirements in
airframes for which Technisonic does not possess an STC.
Approved aircraft types are listed in the attachments to the formal STC documents. These STC's are
the exclusive property of Technisonic and require the written authority of Technisonic for their use. To
assist Factory Authorized Technisonic Dealers in the certification process, we have placed copies of
our Canadian and US STC's on our web site along with a letter of authorization for their use. These
documents may be downloaded and used as support for the technical submission to FAA or Transport
Canada. Only factory authorized dealers/installers are permitted to download and make use of these
documents on behalf of their customers (end users) in support of regulatory agency approval. Please
refer to the Technisonic web site www.til.ca for the latest issue of available STC’s and letter of
authorization for use.
B page

TABLE OF CONTENTS
Paragraph Title Page
SECTION 1 GENERAL DESCRIPTION
1.1 Introduction ............................................... 1-1
1.2 Description................................................ 1-1
1.3 Purpose of Equipment ........................................ 1-1
1.4 ModelVariation ............................................ 1-2
1.5 TechnicalSummary .......................................... 1-2
SECTION 2 OPERATING INSTRUCTIONS
2.1 Features ................................................. 2-1
2.2 OperatingInstructions ........................................ 2-3
2.3 ProgrammingInstructions...................................... 2-3
2.4 PriorityandSelectiveMemoryChannelScanning ..................... 2-4
2.5 ScanningFunction .......................................... 2-5
2.6 DirectFrequencyEntryMode ................................... 2-5
2.7 Receive Frequency Simplex Function .............................. 2-5
2.8 KeyboardLockoutFunction .................................... 2-5
2.9 VariableFrequencyModeFunction ............................... 2-6
2.10 LEDDisplayVariableDimmingMode .............................. 2-6
2.11 90 Second Transmitter Time Out Feature ........................... 2-6
2.13 ProgrammingCTCSSTones .................................... 2-6
2.14 CrossBandRepeat .......................................... 2-7
2.15 PC Memory/Programming Download Capability ....................... 2-7
SECTION 3 INSTALLATION INSTRUCTIONS
3.1 General .................................................. 3-1
3.2 Equipment Packing Log ....................................... 3-1
3.3 TransceiverInstallation ....................................... 3-1
3.4 InstallationKit-Contents...................................... 3-1
3.5 AntennaInstallation ......................................... 3-1
3.6 Installation-PinLocationsandConnections ......................... 3-3
3.7 WiringInstructions .......................................... 3-5
3.7.1 MainPower+28VDC ........................................ 3-5
3.7.2 Main Ground .............................................. 3-5
3.7.3 PTT (Ground Keying) ......................................... 3-5
3.7.4 Front Panel Back Lighting ...................................... 3-5
3.7.5 Audio Outputs (600 and 4 Ohms) ................................ 3-5
3.7.6 Audio Output Ground ........................................ 3-5
3.7.7 Mic Signal Input ............................................ 3-5
3.7.8 MemoryUp/MemoryDown..................................... 3-5
3.7.9 Data Input ................................................ 3-5
3.8 InternalProgrammingEnable/DisableJumper ........................ 3-6
3.9 TransmitterPowerAdjustments ................................. 3-7
3.10 Transmitter Microphone Level Adjustment .......................... 3-7
3.11 SquelchAdjustment ......................................... 3-9
3.12 TransmitterDeviationAdjustment ................................ 3-9
SECTION 3 INSTALLATION INSTRUCTIONS - APPENDIX
PostInstallationEMITest......................................A-1
i

LIST OF TABLES
Table No. Title Page
3-1 9-pinDand15-PinDConnections................................ 3-3
LIST OF ILLUSTRATIONS
Figure No. Title Page
2-1 Operator'sSwitchesandControls ................................ 2-2
2-2 PCUp/DownloadCable-WiringDiagram .......................... 2-10
3-1 OutlineDrawing ............................................ 3-2
3-2 WiringConnections .......................................... 3-4
3-3 InternalEnable/DisableJumperLocations ........................... 3-6
3-4 ExternalAdjustmentAccessHoles ............................... 3-8
3-5 VHFDeviationAdjustmentPotentiometerLocation ................... 3-10
3-6 UHFDeviationAdjustmentPotentiometerLocation ................... 3-11
3-7 VHFLOWDeviationAdjustmentPotentiometerLocation ............... 3-12
ii

1-1
SECTION 1
GENERAL DESCRIPTION
1.1 INTRODUCTION
This publication provides operating and installation information on the TFM-556 Transceiver.
manufactured by Technisonic Industries Limited. The unit offers an extended frequency range
with selectable channel spacing and is intended for use (in the U.S.) only by government
agencies or contractors thereto, who have obtained licensing for operation in the 138-150 MHz
portion of the VHF band. If the TFM-556 transceiver is used in CANADA, VHF operation is
restricted to the following sub bands: 138-144, 148-148.99, 149.005-150.005 and 150.05-
174 MHz. Furthermore the TFM-556 is a frequency agile transceiver which is restricted to
airborne use and must not be operated as a base station in Canada.
1.2 DESCRIPTION
The TFM-556, Transceiver is a frequency agile, fully synthesized airborne FM transceiver
capable of operating in the 66 to 88 MHz, 138 to 174 MHz and 403 to 512 MHz frequency
range in 2.5 kHz increments with either 25 kHz or 12.5 kHz channel spacing. The Transceiver
can operate without restriction on any split frequency pair in either band.
The TFM-556 Transceiver provides 200 operator accessible memory positions per band, each
of which is capable of storing a transmit frequency, receive frequency, transmit frequency
CTCSS tone or DPL code, receive frequency CTCSS tone or DPL code, an alphanumeric
identifier for each channel and wideband (25 kHz) or narrowband (12.5 kHz) channel spacing
assignment. Operating frequency and other related data are presented on a 96 character, four
line LED matrix display. Data entry and function control are performed via a 12 button keypad.
Preset channels may also be scrolled and scanned (scanning only possible in VHF high and UHF
bands) through keypad function activation. Data may also be entered via computer with the
provided software and optional PC Up/download cable, P/N 993390-1.
1.3 PURPOSE OF EQUIPMENT
The TFM-556, VHF High/VHF Low/UHF Band FM Transceiver is designed to provide secondary
airborne communications to facilitate operations which are typically performed in a low altitude
environment. The transmitter sections of this unit have a minimum of 8 watts and do not
exceed 10 watts output power, which may be reduced by a front panel switch to 1 watt, in
order to reduce interference to land based systems.
1.4 MODEL VARIATION
There are four variations of the Model TFM-556 Transceiver. All units offer identical features
and performance except for the following differences:
TFM-556, P/N 031219-1 GREEN display and 28 Volt back lighting.
TFM-556, P/N 031219-1 (5V) GREEN display and 5 Volt back lighting.
TFM-556, P/N 031219-2 RED display and 28 Volt back lighting.
TFM-556, P/N 031219-2 (5V) RED display and 5 Volt back lighting.
Both P/N's 031219-1 and 031219-2 are always provided with 28 Volt back lighting unless a
specific request is made for 5 Volt AC operation.

1-2
1.5 TECHNICAL CHARACTERISTICS
Specification Characteristic
GENERAL
Model Designation: TFM-556
Frequency Range: 66 to 88, 138 to 174
and 403 to 512 MHz
Tuning Increments: 2.5 kHz
Operating Mode: F3E simplex or semi-duplex
Channel Spacing: 25 or 12.5 kHz
Physical Dimensions (including heatsink): Approx. 8.0" X 3.75" X 5.75"
Weight: Approx. 5.1 Lbs (2.3 Kg)
Mounting: Panel Mount via Dzus fasteners
Operating Temperature Range: -45EC to +70EC
Power Requirement:
Voltage: 28.0 Vdc, ± 15%
Current: Receive - 1.2 A Max.
1 Watt Transmit - 2.2 A Max.
8-10 Watt Transmit - 3.4 A Max.
8-10 Watt Dual Transmit
- 5 A Max.
Frequency Selection: 200 memories per band
programmed with:
a) Tx Frequency/Rx Frequency
b) Tx/Rx CTCSS tone or DPL code
c) 9 character alpha numeric title
CTCSS squelch/encoder: All CTCSS tones available
DPL digital squelch/encoder: All standard DPL codes
DTMF encoder: All standard DTMF tones
Audio Outputs: 0.5 Watts into 600 ohms
Speaker Output: 2.5 Watts min. into 4 ohms
Back Lighting: 28 Volts (standard) or
5 Volts (specify)
Display Colour: Green (standard) or
Red (specify)
DPL is a trademark of Motorola Corporation

1-3
1.5 TECHNICAL CHARACTERISTICS (continued)
VHF RECEIVER
Sensitivity at 12 dB SINAD Better than 0.35 µV
Adjacent Channel Selectivity -75 dB (25 kHz)
-70 dB (12.5 kHz)
Spurious Attenuation -90 dB
Third Order Intermodulation -70 dB
Image Attenuation -80 dB
FM Acceptance ± 6 kHz
Hum and Noise Better than 45 dB
Audio Distortion less than 5%
Antenna Conducted Emission less than -70 dBm
UHF RECEIVER
Sensitivity at 12 dB SINAD Better than 0.35 µV
Adjacent Channel Selectivity -70 dB (25 kHz)
-60 dB (12.5 kHz)
Spurious Attenuation -80 dB
Third Order Intermodulation -70 dB
Image Attenuation -60 dB
FM Acceptance ± 6 kHz
Hum and Noise Better than 40 dB
Audio Distortion less than 5%
Antenna Conducted Emission less than -70 dBm
VHF LOW RECEIVER
All specifications identical to VHF receiver.

1-4
VHF, VHF LOW and UHF TRANSMITTER
RF Power Output 1 watt or 10 watts
Output Impedance 50 ohms
Maximum Deviation ±5 kHz (25 kHz mode)
(In narrowband mode) ±2.5 kHz(12.5kHz mode)
Spurious Attenuation -90 dB below carrier level
Frequency Stability ± 2.5 ppm
Microphone Circuit Carbon or equivalent
Sidetone Output 0.5W (max) into 600S
Harmonic Attenuation -60 dB below carrier level
FM Hum And Noise -40 dB
Audio Input 50 mV at 2.5 kHz into
200 Sinput circuit for
±3.5kHz deviation, adjst.
Audio Distortion Less than 5%

2-1
SECTION 2
OPERATING INSTRUCTIONS
2.1 FEATURES
The equipment has several important operating features which provide maximum flexibility,
performance and versatility. These features include:
1. The UHF band can be configured to be operated independently of the VHF High and
VHF Low bands or all three bands can operate as a single unit.
2. The unit can be set up as a cross band repeater, linking a VHF High and UHF frequency
in both directions. The VHF Low band will not cross band repeat.
3. 200 memory positions per band which can each be programmed with a transmit and
receive frequency with 25 or 12.5 kHz channel spacing, Tx/Rx CTCSS tones or DPL
codes and a 9-character alphanumeric title.
4. Scanning of preprogrammed memories with selective memory scanning, in up to 5 scan
lists, for the VHF High or UHF band. The VHF Low band does not scan.
5. Priority scan of memory channel 1 in VHF high or UHF band. The Scan function can
only be used for one of these bands at a time. Simultaneous scanning on both bands
is not possible.
6. Direct frequency entry mode.
7. Receive frequency simplex function. (Repeater talk around)
8. Switchable RF output power between 1 watt and 8-10 watts.
9. Lockout of keyboard to prevent inadvertent entries.
10. Variable frequency mode to manually scan up and down in 1MHz, 100kHz or 2.5 kHz
steps.
11. LED display variable dimming mode.
12. Selectable 90 second Tx time out feature.
13. PC Memory Upload or Download capability.
14. Configuration Menu - Pressing ENTER, RCL and FUNC together while turning the radio
on will put it into configuration mode. The programming features
affected are:
a) DPL - Can be turned on or off with the MUP and MDN
(4 and 7) keys. This only removes the DPL entry
step from the programming sequence and does not
stop memories that already have DPL codes from
working. This also applies to the rest of the on/off
configurable items.
b) Scan - Can be disabled. Selecting FUNC and SCAN will
do nothing if Scan is off. The scan list indicator (+)
will still display if was previously programmed.
c) Rx CTCSS - Can be turned on or off from the
programming sequence. This affects only the
CTCSS tones for receive.
d) LAST MEM - If set to on, the last memory channel on
the display will be what comes up when the
radio is turned on. If set to off, the last memory that
changes were made to will be what comes up when
the unit is switched on.
e) DUALMODE - If set to ON, the UHF band is operated independently
from the 2 VHF bands. (ie./ UHF audio separately available on 9-
pin connector). The radio is shipped with this feature OFF.

2-2
f) REMOTE BS - Only used when an RC-550 slave control head is
attached. Setting this feature on will give the transmit selection to
the Band Select switch on the RC-550 rather than on the radio.
This is useful when the operator at the RC-550 is using the VHF
high and low bands. Regardless of whether this feature is set to on
or off, the fourth squelch light will light on both units when both BS
switches are set to the same position.
g) SIDETONE - The TX audio circuit becomes active allowing you to adjust
the sidetone level with the VHF volume knob. When the desired
level is reached, press ENTER and this level will be set for both
VHF and UHF bands. The factory setting is 23.
Note: The sidetone level must be set every time you go through the
configuration menu since it takes the setting of the volume knob
regardless of whether you set it or not.
FIGURE 2-1 Operator's Switches and Controls

2-3
2.2 OPERATING INSTRUCTIONS (See Figure 2-1)
1. Switch power on by turning the VHF volume clockwise. Depending how the radio is
configured, either the last programmed or last displayed frequencies will appear on the
screen. The transceiver is now in normal operating mode. NOTE: VHF high band will be
referred to as “VHF” and VHF low band as “VLO” in these instructions.
2. Adjust the audio level by adjusting the VHF, UHF and VLO volume knobs.
3. Pressing the squelch defeat button will open all receivers to confirm they work.
4. Read the display. The top line will indicate which VHF memory is selected followed by a "+"
if the memory position is included in a scan list, an alphanumeric message, and the
frequency of the VHF receiver. A small "n" before the frequency indicates 12.5 kHz
narrowband channel spacing is in effect on this memory position. In the receive mode, the
frequency is followed by an "RT" if an RX CTCSS tone or RX DPL code is programmed, or
an "RX" if no receive tone/code is programmed. Similarity, in the transmit mode either a "TT"
or "TX" is shown after the frequency. The second line shows the same information for the
UHF band. The third line indicates the same information about the VHF LOW band.
5. Set the VHF/UHF/VLO (BS) switch to the desired band.
6. The VHF/PRI switch is spring loaded and is normally in the VHF position. Pressing this
switch down will result in channel 001 being loaded on the VHF band.
7. Set the HI/LO switch to the desired RF output power.
8. Select the desired memory by using the M.UP and M.DN buttons, or the RCL button
and a three digit number followed by ENTER.
9. To transmit DTMF tones, use the keyboard keys while holding the PTT button on the
microphone. There is a 5 second PTT delay after pressing a key so that you may press
several DTMF keys in sequence without having to hold the PTT. The keyboard returns to its
normal function when the PTT is released.
The display always shows the status of both receivers and the transmitter. The light at the left of each
line indicates which receiver is receiving. The display also indicates the memory channel is in use.
A "TX" (no TX tone/codes programmed) or "TT"(either TX tone or code programmed) on the right
side of the display indicates which band is active when transmitting. The transmit frequency is also
shown. In the receive mode the display shows “RX” beside the receive frequency if no RX tone or
DPL code is programmed and “RT” if a CTCSS tone or DPL code is programmed.
While in any programming mode, all receivers continue to function. When the transceiver is in either
of the operating frequency or CTCSS tone/DPL code programming modes and you must respond
to a call, click the microphone PTT once (the radio will not transmit during this click). This will cause
the transceiver to revert back to the normal operating mode and communications with the caller can
proceed in the usual fashion. Pressing the FUNC key has the same effect.
2.3 PROGRAMMING INSTRUCTIONS
To program one of the 200 memory channels in one of the bands:
1. Select the desired band on the band select (VHF/UHF/VLO) switch. This is required before
any of the programming modes or functions.
2. Press the FUNC key. The display will show the function prompt.

2-4
3. Press the PROG key. The display will show the current receive frequency with a flashing
curser on the first or second digit (The first digit is always a one <1> on the VHF band and
there is no hundreds digit on the VHF LOW band).
4. Type in the desired receive frequency. If you type in a frequency which is not a 2.5 kHz step,
the nearest valid frequency will be automatically selected.
5. The curser will return to the second digit. You can retype the frequency if you have made an
error or press ENTER to continue.
6. The transmit frequency will be displayed with the curser on the second
digit. Follow the same method as in step 4 and 5.
7. The channel spacing increment of either 25.0 or 12.5 kHz is now displayed. Use the
M.UP and M.DN keys to select the desired channel spacing for the memory position,
then press ENTER.
8. The alpha-numeric title is now displayed. Use the M.UP and M.DN keys to scroll through
the alphabet, numbers and symbols. When the desired character is displayed, press
ENTER to advance to the next character. Press “1" to backspace.
9. Keep repeating step six until the last space is set (there are 9 characters). The display will
show SCAN or LOCKOUT to enable this memory position as part of a scan list or lock it out
of the scan lists. Use the 1,2,3,4,5 and M.DN keys to toggle between these functions (for
details see paragraph 2.5). Once the desired condition has been selected, press ENTER.
The TFM-556’s display will show a "+" beside the memory channel number if scan is
enabled. Note: Scan function and Scan list feature not provided for VHF Low Band.
10. The display will now show the current memory number. Type in the 3-digit number of
the memory you want to save to (if different from displayed one) and press ENTER.
2.4 PRIORITY SCANNING, SELECTIVE MEMORY CHANNEL SCANNING AND SCAN LISTS
Instead of breaking up the 200 channels into blocks for scanning, the TFM-556 has 5 scan lists per
band (VHF high and UHF only). Any of the 200 channels can be assigned to any one or more of
these 5 scan lists. This means the channels do not have to be repeated for them to be in more than
one block and that you are not limited to the number of channels that can be scanned at once, since
all 200 channels can be put into any scan list. Scanning is not available on the VHF Low band.
The priority memory channel is always memory position number 1. The priority memory channel
is scanned every other step (ie. 121314151...) to ensure that no incoming messages are missed.
The priority channel can be locked out, which will result in the normal scanning of the other memory
positions.
Selective memory scanning allows the user to select which of the 200 memory channels are
to be scanned or locked out when the scan function is invoked. To use this feature, follow
PROGRAMMING INSTRUCTIONS found in paragraph 2.3. Once the screen displays SCAN or
LOCKOUT, use the 1,2,3,4,5 or M.DN keys to toggle to the desired condition and press ENTER.
Entering the any or all of the numbers 1,2,3,4 or 5 will include that memory channel in any of the five
scan lists. In normal operating mode the display will later show a "+" beside the memory channel
number if it has been included in any of the 5 scan lists.

2-5
2.5 SCANNING FUNCTION (5 second talkback delay)
Select the band you wish to scan with the band switch. (You can not scan VHF Low band).
To start scanning of the memory channels, press FUNC then SCAN and then the number (1,2,3,4,5)
of the desired scan list.
The radio will scan through all the preset memory positions in the selected scan list (see above
paragraph for priority and selective scan features) and will lock on to the first active channel in the
scan sequence. It will remain on the channel until it becomes inactive. Scanning will resume again
after five seconds of inactivity. To exit the scan mode, press the SCAN key. This will cause the radio
to revert back to the normal operating mode.
If while scanning, you hear a call for you:
1. Respond to the call within 5 seconds. When scanning is interrupted by an
incoming signal, the channel will remain open for five seconds before resuming
scanning.
2. During communications the five second timer is reset from the last Rx or Tx
signal encountered.
The radio resumes scanning once the Rx or Tx activity has ceased for more than five seconds.
The SCAN key must be pressed to exit the scan mode.
2.6 DIRECT FREQUENCY ENTRY MODE
This mode is designed to facilitate quick frequency selection during emergency and other operational
conditions requiring direct operating frequency selection. This operating mode is disabled along with
the programming mode when the internal disable jumper is set.
1. When the transceiver is in the normal operating mode, press FUNC and the desired
operating frequency ie/ 153.2750.
2. On the UHF band press FUNC and then 1and the desired frequency ie/ 443.5500.
3. You will then be asked for 12.5 or 25.0 kHz channel spacing. Select with MUP or MDN and
press ENTER.
Please note in the above operation, after FUNC and "1" are entered, the LED display will show
memory channel "000" and then the remaining digits in the desired frequency are shown as they are
entered. No alphanumeric message can be entered in this mode. Operation on the new frequency
occurs in both transmit and receive (simplex only) modes. If RX or TX CTCSS tones/DPL codes are
required they must be programmed in afterwards.
2.7 RECEIVE FREQUENCY SIMPLEX FUNCTION (Repeater Talkaround)
The receive frequency simplex function allows you to quickly change the transmit frequency, when
operating on a split pair (repeater/semi-duplex mode), to the receive frequency to allow direct
communications. ie/ If you are transmitting on 152.000 MHz and receiving 152.555 MHz, select VHF
on the band select switch and press FUNC then UP to transmit on 152.555 MHz. To return to the
split pair condition, you must recall the memory channel again. This is quickly done by pressing M.UP
for one step up, then back down one step with the M.DN key.
2.8 KEYBOARD LOCKOUT FUNCTION
The keyboard can be locked out so that accidental pressing of keys does not change
frequency, etc., unknowingly to the operator. To lock the keyboard, press FUNC then LOCK. This
will disable all keyboard functions (except keyboard unlock) in the receive mode. The DTMF function
during transmit will not be affected. To unlock the keyboard, press and hold the LOCK key for two
seconds until the display indicates "UNLOCK".

2-6
2.9 VARIABLE FREQUENCY MODE FUNCTION
To enter variable frequency mode, press RCL, 0,0,0, then ENTER or enter a frequency in the direct
entry mode described above. The memory channel that you were just in will still be valid but now you
can manually adjust the frequency with the M.UP, M.DN, UP and DN keys. The UP and DN keys will
make the frequency count up or down in steps of 2.5 kHz. The M.UP and M.DN keys will make the
frequency count up or down in steps of 1 MHz. You can not change the label. The frequency in this
mode can not be stored in memory. To exit this mode, recall one of the 200 memory channels (ie.
RCL, 0,0,1). Variable frequency mode is disabled when the internal entry disable jumper is removed.
2.10 LED DISPLAY VARIABLE DIMMING MODE
1. With the transceiver in normal operating mode press the UP or DN keys to increase or
decrease the intensity of the LED display.
2. Once maximum intensity of the display is achieved, the UP key no longer functions.
Conversely once minimum intensity is reached, the DN key ceases to function.
2.11 90 SECOND TRANSMITTER TIME OUT FEATURE
A selectable 90 second transmitter time out feature is provided to prevent accidental continuous
transmission in the event of a faulty PTT switch. With this feature enabled the transceiver will stop
transmitting after the PTT is engaged continuously for 90 seconds. The timer is reset by releasing
then re-engaging the PTT switch.
Press the FUNC then the M.UP key. Use the M.UP and M.DN keys to select 90 SEC, which
enables the feature, or NONE which disables it.
2.13 PROGRAMMING CTCSS TONES/DPL CODES
CTCSS tones (PL tones) or Digital DPL codes can be assigned to each memory channel on any
of the three operating bands. To program a tone/code to a memory channel:
1. Select the desired band on the band select switch.
2. Use the M.UP and M.DN keys to select the memory channel that you want to assign
a CTCSS tone or DPL code.
3. Press the FUNC key then the TONE key. The display will show "RX TONE:" and the
current tone number, as well as the tone frequency in Hz.
4. Use the M.UP and M.DN keys to select the tone number you require. The following
is a list of the available CTCSS tones:

2-7
Number Tone Number Tone Number Tone
01 67.0 26 162.2 51 177.3*
02 71.9 27 167.9 52 183.5*
03 74.4 28 173.8 53 189.9*
04 77.0 29 179.9 54 196.6*
05 79.7 30 186.2 55 199.5*
06 82.5 31 192.8 56 206.5*
07 85.4 32 203.5 57 210.7*
08 88.5 33 33.0* 58 218.1*
09 91.5 34 35.4* 59 225.7*
10 94.8 35 36.6* 60 229.1*
11 97.4 36 37.9* 61 233.6*
12 100.0 37 39.6* 62 241.8*
13 103.5 38 44.4* 63 250.3*
14 107.2 39 47.5* 64 No Tone
15 110.9 40 49.2* (carrier squelch only)
16 114.8 41 51.2* (The tones marked with * are
17 118.8 42 53.0* nonstandard tones).
18 123.0 43 54.9*
19 127.3 44 56.8*
20 131.8 45 58.8*
21 136.5 46 63.0*
22 141.3 47 69.4*
23 146.2 48 159.8*
24 151.4 49 165.5*
25 156.7 50 171.3*
4. Press ENTER. "TX TONE" appears on the display. Repeat step 3.
5. The display will now show "RX DPL:" and the current 3-digit DPL code. If no DPL
code is required "000" should be entered. Please note that if a DPL code is to be
programmed a CTCSS tone should not be enabled.
6. Use the keypad to enter the required octal 3-digit DPL (Digital Coded Squelch or DCS)
code. A list of all usable and unique octal 3-digit DPL/DCS codes follows:
017* 051 116 156 243 266* 346 431 466 612 721
023 053* 122* 162 244 271 351 432 503 624 731
025 054 125 165 245 274* 356* 445 506 627 732
026 065 131 172 246* 306 364 446* 516 631 734
031 071 132 174 251 311 365 452* 523* 632 743
032 072 134 205 252* 315 371 454* 526* 654 754
036* 073 143 212* 255* 325* 411 455* 532 662
043 074 145* 223 261 331 412 462* 546 664
047 114 152 225* 263 332* 413 464 565 703
050* 115 155 226 265 343 423 465 606 712
* indicates GE Digital Coded Squelch (DCS) Code
7. Press ENTER. "TX DPL" appears on the display. Repeat step 6.

2-8
2.14 CROSS BAND REPEAT
The TFM-556 can act as a cross band repeater between VHF (high band only) and UHF. To enter
repeat mode, press FUNC and then 9. The status line will show REPEAT instead of the band switch
selection. When a signal is received on one of the bands, the audio is routed to the transmitter of the
other band. This process can only go in one direction at a time. While transmitting, short bursts of
noise due to intermittent signal strength or interference will be muted while the transmitter continues
to transmit. There is also a short delay of silence (tail) after the received signal ends. The operator
at the TFM-556 can monitor communications in both directions but can only talk to one band at a
time via the band select switch. If the radio is set up in dual mode, the band selection is made at the
audio panel. To cancel cross band repeat mode, press ENTER.
2.15 PC MEMORY PROGRAMMING UP/DOWNLOAD CAPABILITY
The TFM-500 transceiver can be programmed by a Windows based personal computer using
Technisonic software supplied on CD with each TFM-556.
Requirements:
1. PC compatible computer with a CD ROM drive, running Windows 95/98/NT/2000/ME.
2. Bench power supply of 28 volts DC.
3. PC download cable, P/N 993390-1 which can be supplied or made from the wiring
diagram at the back of this section.
Connections:
1. With the PC turned off, plug the 25 pin male 'D' connector into a serial port.
2. Plug the 9 pin 'D' connector into the back of the TFM-556 transceiver.
3. Connect the power supply to the TFM-500.
Installing the MultiTDP Program:
The CD supplied with each radio contains software for all of Technisonic’s downloadable
transceivers. Place the CD into your drive and use Windows Explorer to open the MultiTDP
directory on the CD. Double click the MultiTDP_Install.exe file. Follow the onscreen instructions
to install the program onto your hard drive. When the program is installed, it can be run by
selecting Programs from your Start menu, then select Technisonic from the submenu and finally
MultiTDP.
Using the MultiTDP Program:
With the program running on your computer, a full MultiTDP instruction manual can be loaded
by selecting Documentation in PDF format under the Help menu. Otherwise, to get started, pull
down the File menu and select TFM-500. The program defaults to serial port com1 but can be
set to com2, 3 or 4 under the Com Port menu. The program is now ready to use. You may
want to upload data from the radio and edit channels or start a new data file. The VHF and
UHF bands are treated as separate radios and must be up or downloaded and edited separately.
Editing is done on a channel by channel basis. Set the channel number you would like to edit
and then modify the frequencies, labels, CTCSS tones, DPL codes, wide / narrow band setting
and scan lists as desired. Press the Save Record button to store the changes youv’e made to
the data base below. After you have edited the channel list your can save your changes to disk
and/or download to the radio. Only channels selected with a check mark will download. It is

2-9
recommended to use the Select All command in the Data Transfer menu to ensure the data
base in the radio matches the one in the PC. When download is selected, a message box will
appear on your screen asking you to press FUNC and DN on the radio. Press these buttons on
the radio
before you click OK in the message box, otherwise the download will fail.
TFM-556 Upload/Download Programming Cable
P/N 993390-1 Wiring Diagram
Note: If your serial port is a 9 pin connector, instead of the 25 pin use a female
9 pin D connector, connecting:
Yellow - pin 3
Blue - pin 2
Black - pin 5
FIGURE 2-2 TFM-556 Transceiver PC Up/Download Cable - wiring diagram

2-10
SECTION 3
INSTALLATION INSTRUCTIONS
3.1 GENERAL
This section contains information and instructions for the correct installation of the TFM-556,
VHF/FM Transceiver. Make certain that the correct frequencies are preprogrammed in accordance
with the equipment user's valid FCC operator's license, prior to installation.
3.2 EQUIPMENT PACKING LOG
Unpack the equipment and check for any damage that may have occurred during transit. Save
the original shipping container for returns due to damage or warranty claims. Check that each
item on the packing slip has been shipped in the container. Verify that the equipment display
and backlighting configuration are the same as those ordered.
3.3 TRANSCEIVER INSTALLATION
The TFM-556 transceiver is designed to be Dzus mounted and should be installed in conjunction with
an IN-550 installation kit. See Figure 3-1 for an outline drawing of the unit with dimensions to
facilitate the installation.
3.4 INSTALLATION KIT - CONTENTS
The IN-550 installation kit consists of:
1. One 15 pin Cannon D mating connector (female) complete with crimp pins and hood.
2. One 9 pin Cannon D mating connector (male) complete with crimp pins and hood.
3. Three BNC antenna mating RF connectors (male).
3.5 ANTENNA INSTALLATION
Antenna, P/N’s ATM-150, ATM-403 and ATM-30 may be obtained from Technisonic Industries
Limited or suitable equivalent 0dB gain antenna may be utilized with the TFM-556 transceiver.
The antennae should be mounted on the bottom of the aircraft whenever possible and must
be located at least 20 cm (8inches) from any occupant in the airframe. Consult with
instructions provided with the antennas. Connect RF cables from antennas to the back of the
TFM-556 unit by utilizing the BNC mating connector provided in the installation kit. The VHF
Low band (top) and UHF (middle) BNC connectors are located on the rear, above the 15-pin
D connector and the VHF high band BNC connector is below the 9-pin D. If an external antenna
tuner (ATU) is to be used, the ATC-550 (p/n 991102-1) will have to be utilized to control it.
The ATC-550 is an external box to the TFM-556.
3.6 INSTALLATION - PIN LOCATIONS AND CONNECTIONS
The pin numbers and locations for the 15 pin and 9 pin Cannon D located on the rear of the
TFM-556 transceiver are shown below. Pin connections are in provided in TABLE 3-1.
Transceiver mounted view of 15 pin female and 9 pin male connector

3-1
FIGURE 3-1 Outline Drawing for Model TFM-556 Transceiver