• Kessler Engineering image

Auto Tuner

The AT-AUTO satisfies the demands of the discerning ham for an automatically controlled antenna tuner. Unlike competing products with loud, clacking relays and burning relay contacts, the AT-AUTO uses stepper motors, under microprocessor control to precisely position a "real" roller inductor and a "real" air-dielectric variable capacitor. The AT-AUTO does not relay-switch discrete capacitors and inductors.

  • Stepper Motors
  • u-Processor Control
  • Unique Features
  • 1.5kW CW Operation
  • Auto Retunes
  • Periodic Firmware Updates
Learn More

Coaxial Switch

The CX-AUTO coaxial switch features an embedded microprocessor controller and is primarily intended as a companion product for the AT-AUTO. The CX-AUTO enables selection of any 1-of-8 coaxial outputs and receives selection commands via a serial data interface. When interfaced with an AT-AUTO, the tuner may be configured to associate any of the CX-AUTO's 8 coaxial outputs with an amateur radio band and to automatically command the CX-AUTO to select that particular coaxial output when QSYing to that band.

  • u-Processor Control
  • Serial Data Interface
  • Two RF Outputs
  • Balanced output
  • CI-V Interface
  • More Features
Learn More

A Little About Us

Kessler Engineering is a privately owned electrical engineering venture providing innovative solutions through design consultation, new product development, and electronics manufacturing.

Learn More

Update Your Tuners

Kessler Engineering will make the latest versions of the tuner's firmware available for download. Support for older firmware versions is available here, too.

AT-AUTO Tuner Page

Contact Us!

Use our contact form to request technical support, ask questions, etc.
Please check our FAQ Page to see if we have your question answered there.

Contact Us Page

Amateur Radio Products

Kessler Engineering, LLC's primary amateur radio products are automated antenna tuners, shack automation products, and associated accessories. The flagship of the Kessler Engineering LLC product line is the AT-AUTO, Automatic Antenna Tuner.

In 2005, Don Kessler began designing an automatically controlled impedance matching network (an antenna tuner). That design quickly evolved into the popular AT-AUTO antenna tuner. The AT-AUTO first went on sale at the 2006 Dayton Hamvention®.

Since then the AT-AUTO has matured and evolved in an attempt to satisfy the wishes of the growing customer base. During the past 5+ years, the AT-AUTO has become very highly sought after and has garnered a well-deserved reputation for its robustness, sophistication, and ease of use. Much of this is due to the fact that the AT-AUTO firmware is continually evolving, permitting addition of user-requested capabilities and new features.

While the AT-AUTO firmware has continued to evolve and mature, the AT-AUTO hardware had remained fundamentally unchanged from the first models that came off of the product line in early 2006. AT-AUTO product improvements have primarily been limited to updates and enhancements to the firmware, with only minor hardware changes. However, in order to keep the AT-AUTO relevant and competitive, we are now at the point where the hardware configuration may begin to hinder the ability to add several significant new (hardware) features. In short, it is time to dust off and update the AT-AUTO hardware design. For this reason, the AT-AUTO production is temporarily on-hold as we concentrate our efforts on the re-design of the AT-AUTO hardware.

A companion product to the AT-AUTO is the CX-AUTO. This was our solution to expanding the singular coaxial output available on the AT-AUTO. The CX-AUTO is an automatic coaxial antenna switch which is controlled by the AT-AUTO, giving the user the ability to use any one-of-eight coaxial-fed antennas with the AT-AUTO.

Custom RF Products

Kessler Engineering also provides electrical engineering consulting services, custom design of embedded control systems, unique RF product design, and electronic product fabrication. Dr. Kessler's expertise includes Power RF Electronics with an emphasis on Class-E RF amplifiers. Contact us directly for further details.

Order with confidence from Kessler Engineering!

Discover More

We Ship Via

Order Securely

Company Info

Kessler Engineering, LLC

Tel: 937.813.5667

Member Of

Kessler Engineering, LLC is a member of the Association of Old Crows
Kessler Engineering, LLC is a member of the Institute of Electrical and Electronics Engineers