The II Morrow / Garmin AT Apollo SL-70 Transponder offers comparable performance to Garmin's GTX-327. Garmin purchased II Morrow / UPS AT and ultimately discontinued the SL-70, but at one time these radios were direct competitors.

There are not many new SL-70 installations being performed.  This listing is best for an owner/pilot with a malfunctioning SL-70.  If the SL-70 was meeting your needs, and you do not want to perform a new Transponder installation, a replacement SL-70 may be the right choice.  We have working SL-70 Transponders, but the faceplates are not in good condition. If you send us your core, we will swap faceplates, and send you the working SL-70.

The SL-70 is a very powerful transponder. It produces a minimum of 250 watts of transmission power, and the manual states that 325 watts is the typical output. This ensures your position and altitude are noted at very long range.

In the interest of reliability, the SL-70 automatically begins its self-test function if it has not been interrogated in the last 30 seconds.

Additionally, the SL-70 offers an innovative Altitude Hold feature. When you reach your assigned altitude, press the "Hold" button. You may set an altitude buffer between 200 feet and 2500 feet, in 100 foot increments. (The default is 300 feet.) The SL-70 will alert you if your altitude drifts more than the allowed buffer.

The SL-30 is only 1.3 inches high, offering placement flexibility.

The SL-70 features:

• Easy-to-read digital LED display
• Dedicated VFR button to squawk 1200
• Displays pressure altitude from your encoder
• Accepts either gray code or RS-232 serial encoder input
• 4096 discrete codes
• Mode C compatibility
• System test capability
• TSO'd

You may also be interested in an Encoder to use with this SL-70. When installed with an Encoder, the SL-70 will report both your position and altitude to ATC (Mode C).

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