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Overview
The Cambridge 302 Direct Digital Variometer (DDV) has sensors for altitude, airspeed, acceleration, engine noise level, and temperature. It gives visual and audio climb and speed-to-fly information; and it displays climb rate, average climb rate, altitude and MacCready setting. The 302 includes an integral GPS receiver that generates IGCapproved Secure Flight Logs.

Calibration and performance adjustments are firmware based. The 302 is altitude and temperature compensated. Flash memory is used for firmware as well as flight logs. Firmware upgrades are distributed via the Cambridge web site on the Internet. There are 4 models of the 302 DDV:

Model	Dial Plate
302E	English dial plate (knots)
302M	Metric dial plate (m/s)
302E-MG	Motorglider (knots)
302M-MG	Motorglider (m/s)

The 302 supports an auxiliary NIMH battery pack (CA-117). During normal flight the instrument keeps the auxiliary battery charged. If the glider’s main battery fails, the auxiliary battery powers the complete Cambridge 300 system for more than two hours.

302 Display Screens
The 302 has a built-in, multi-page LCD display behind a stepper-motor driven vario needle. This display has 12 screens that are selected by successively tapping the control knob. These are:

Page	Display	Control Knob Controls
Home	altidude, averager, MacCready, speed director, climb/cruise mode, GPS signal	audio volume
1	MacCready setting	MacCready setting (kts or m/s)
2	altitude, altimeter setting	altimeter setting (mBar or ”Hg)
3	battery voltage	supply battery: 1 = glider, 2 = auxilliary (CAA 117)
4	audio response time	audio response time
5	vario pointer response time	vario pointer response time
6	home screen with alternative altimeter	altimeter (ft, flight level, GPS alt, pressure alt)
7	ballast %	ballast %
8	slow-alarm threshold	slow-alarm threshold (kts or km/hr))
9	TE compensation %	TE compensation %
10	sensor readings
11	diagnostics	pointer position

Optional Display Devices
In addition to the built-in display, two optional display devices may be connected to the 302. The Model 303 LCD Navigation Display is an economical basic navigation display that was used with the GPS-NAV.

You may also connect a PDA device, like the one pictured here, for moving map navigation as well as other critical soaring flight information, depending on the PDA software you choose. Cambridge does not sell the PDA or software. You will need to gather these items from various sources. Following are high quality software programs that run on PDAs and work with the 302:

Glide Navigator II

Pocket StrePla

WinPilot

Features
Since the 302 knows the glider's airspeed, it can calculate total energy digitally, without a total-energy probe. It can also operate with a total-energy probe. CAI recommends using the total-energy probe configuration for best performance.

Installation
The 302 fits a standard 57 mm (2.25”) instrument hole. The knob shaft at the lower left of the instrument face fits through the standard instrument mounting screw hole. You will need either a PDA or a lap-top computer at the glider to download logs. An adapter kit is available for mounting in an 80 mm hole.

The Cambridge DDV is supplied with ALL parts necessary for installation as follows:

• 302 Standard Power Cable (CAA-114)
• white-tipped Outside Air Temperature (OAT) probe (CAA-115)
• 6 foot (2 meter) beige serial data cable (HA-349)
• plastic laminated Operator’s Card (MA-012)
• hard copy User’s Guide (MA-013)
• CD-ROM with all programs and documents
• spare power cable (CAA-116)
• small screwdriver for the plug and connector strip (TL-001)
• 1 meter of soft silicone rubber instrument tubing (WA-044)
• 3 Tee (HA-100) and 3 Straight (HA-101) tubing connectors
• 15 small tie wraps
• GPS antenna with SMC connector (HA-435)
• remote speaker (CAF-031) (Motorglider model only)

Power and logic connections are on a screw type, 10-position connector on the back of the instrument. The pin assignments are as follows:

1. +12 volts unswitched power (bottom of connector)
2. +12 volts switched primary power
3. *Cambridge auxiliary battery (option CAA-117)
4. *external speaker (8 ohm, optional)
5. *external speaker return
6. *On-Off(if pin 2 used)/PEV switch (momentary to pin 10)
7. *Airbrake switch (connects to pin 10 when airbrakes not locked)
8. *Landing gear switch (connects to pin 10 when gear not extended and locked)
9. *Cruise/climb switch (toggle to pin 10 for climb mode)
10. Power ground (top of connector)
    * optional connections

If the positive side of the glider battery is connected to pin 1, the 302A will be ON. This pin allows for external switching of 302A power. When the positive side of the battery is connected to pin 2, pressing the Pilot Event (PEV) button on the front of the instrument, or pressing the ON button of the 303 display (if used), turns on the instrument. In this case, no external power switch is needed. Pin 3 is for the optional Cambridge auxiliary battery (CAA-117) only. This back up battery supplies power to the 302A in the event the glider's power fails. It is charged from the glider's power system during normal operation. If an in-flight power failure occurs, the auxiliary battery will supply power for at least two hours if fully charged. If the glider is not flying and the glider's battery fails or is switched off, the 302A will recognize the situation and turn itself off after about two minutes.

The CAA114 Power Cable (for use in the aircraft) has a pre-wired six position ground terminal strip in addition to the ground pin on the main ten position connector.

Unlocking the airbrakes connects pin 7 to ground. When airspeed rises above 25 knots, the alarm sounds. The alarm is cancelled when the airbrakes are locked. During flight with the landing gear retracted, unlocking the airbrakes connects pin 7 to ground and sounds the alarm. Lowering the landing gear opens the connection between pin 8 and ground and cancels the alarm.

The 302 switches automatically from cruise mode (with speed-to-fly arrows and tones) to climb mode. If no cruise/climb switch is installed, mode switching is based on changes in GPS track.

The GPS antenna supplied with the 302A should have a good view of the sky. It will not interfere with the glider’s compass. It

Pneumatic connections are required for the Pitot probe, static ports and total enerty probe. No flask is required.

The temperature probe should be placed in a ventilation duct to sense moving outside air.

Warranty
All Cambridge Aero Instruments Products are guaranteed against defects for two years from date of original purchase, when used in gliders.

Documentation
302 Manual
302 Dataport User's Guide - Version 2.0
(These documents require Adobe Reader.)

CAI Model 303 LCD Navigation Display

$395.00

CAI Model 306E Vario Repeater (Knots) $525.00 CAI Model 306M Vario Repeater (Metric) $525.00

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