The below is a description cut/pasted from the Bennett Avionics site:
The Garmin GTX-320A is an updated version of the GTX-320. According to the factory, this change was made in the interest of manufacturing efficiency. The GTX-320A has more parts in common with the GTX-327, which reduced Garmin’s manufacturing costs. (We have not noticed any performance or reliability difference between the GTX-320 and GTX-320A.)
The GTX-320A produces 200 watts of transmission power, offering long range and operation up to 50,000 feet. Plus, the GTX-320A does this without a cavity. As a result, reliability is improved, and no warm-up time is needed before operation.
The GTX-320A features:
- 4096 discrete codes
- Mode C compatibility
- System test capability
There are a couple features that ease the installation of the GTX-320A, saving you time and money. This transponder will operate with either 14 or 28 volts, and it does not require a dropping resistor when used with 28 volts. Also, optional adapters are available to make this unit a slide-in replacement for the following transponders:
- King KT-78A
- King KT-76A
- Narco AT-50A
- Narco AT-150
If you are replacing one of these transponders, your unit has trade-in value. Please contact us for the latest core credit.
You may also be interested in an Encoder to use with this GTX-320A. When installed with an Encoder, the GTX-320A will report both your position and altitude to ATC (Mode C).
Installed new in 3/2005. Unit functions perfectly and never had any technical or mechanical problems. Removed and replaced unit with an ADS-B-out compliant Stratus ESG transponder.