Garmin SL 70 User Guide

Apollo

Mode C Transponder

Model SL70

Operation Manual

August 2003 560-0401-00a

Using Altitude Hold

Altitude Hold helps you maintain a constant altitude. The current pressure

altitude is stored as a reference and is the displayed value unless Altitude Hold is

activated. The hold altitude is displayed in 100-foot increments. The displayed

altitude is the same as is sent for Mode C interrogation replies. When the HLD

button is pressed, the altitude display will be set to “+000.” The altitude display

values will increase/decrease as the aircraft changes altitude. The altitude display

will flash when the aircraft change in altitude exceeds the selected threshold.

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MALL knob to change the buffer value, such as ±02. Press HLD

LED above the HLD button will light to indicate Altitude Hold is active.

100-foot increments. A displayed value of +001 means you are 100 ft above

the hold altitude.

Setting the Hold Altitude

1. Press the HLD button to set the current altitude as the hold altitude. The

2. The Altitude display now shows a value that is relative to the hold altitude in

seconds, or longer. Select a value between 200 and 2500 feet. The factory

Setting the Altitude Hold Buffer

1. Set the Altitude Hold Buffer value by pressing the HLD button for two

again to save the value.

default value is 300 feet. The value is retained when the SL70 is turned off.

Displays

2. Turn the S

Squawk Codes

The four-digit squawk code is shown on the left side of the display.

Altitude

The Altitude display is used to show the pressure altitude, Hold Altitude, and

Hold Altitude buffer with 100 ft resolution.

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LARGE knob clockwise one more

7500 - Hijacking

Special Squawk Codes

1200 – Default VFR code in the USA.

7700 – Emergency

7600 – Loss of communications

Press for Mode A operation. The SL70 is “on” and will transmit its squawk code

when interrogated.

LARGE knob clockwise one position. The first character of the

squawk code will flash.

ALT

Press for Mode C operation. The SL70 is “on” and will transmit its squawk code

VFR

and altitude when interrogated.

Press VFR once to set the VFR squawk code. Press VFR a second time to toggle

HLD

between the VFR squawk code and the previously entered code.

Press to enable/disable altitude hold. The LED above the HLD button is lighted

when altitude hold is enabled.

Selecting a Squawk Code

The selected squawk code will always be in use. As you change a squawk code,

the original code will be sent until you are finished selecting the new code. When

changing a code, the display will stop flashing and selection is stopped if the

controls are not used for three seconds or more. Pressing any pushbutton will also

end code selection. The squawk code is automatically reset to the VFR code when

the SL70 is turned back on.

1. Rotate the

LARGE knob to move the cursor to the next desired digit. Turn the

SMALL knob to the desired number for the first digit.

SMALL knob to select the desired number.

3. Rotate the

2. Rotate the

position. The display will stop flashing and the new code will be sent.

4. Repeat step 3 for each of the desired digits.

5. After the last digit is selected, rotate the

See the Airman’s Information Manual for more information about squawk codes.

Apollo SL70

The Apollo SL70 Mode C Transponder complements the Apollo SL series of

slimline avionics. The SL70 provides Mode A/C functionality certified to TSO-

C74c Class 2A meeting VFR and IFR requirements, operates on 10-35 VDC,

includes squawk code display and selection, standby, altitude, and ident

operation. All of these features are contained in the space-saving 1.3”H x 6.25”W

form factor, with bright easy-to-read LED characters, and user-friendly operation.

A photocell on the front of the SL70 adjusts the LED intensity for ambient light

conditions. The SL70 will automatically test its receive function if no

interrogations have been received in the last 30 seconds.

Knobs

A single knob on the left side controls power on/off. Rotate the knob clockwise to

turn transponder power on. Rotate the knob counterclockwise to turn power off.

Dual concentric knobs on the right side are used to select squawk codes and

change altitude values. Turning the large, outer knob moves the cursor to allow

editing of the selected character. Turning the small, inner knob changes values.

Pushbuttons

Press the pushbutton once to activate the selected operation. An LED above each

IDENT

pushbutton will light when that button is pressed.

Press the IDENT button once to reply with an identifying squawk code, Ident

mode. In Ident mode, the Reply LED will be lighted for 20 seconds. The Reply

SBY

(Ident) LED will also flash when the SL70 generates transponder replies.

Press SBY to place the transponder in “Standby” mode. The SL70 is “on,” but no

information will be transmitted.