Safe Power for the Ten Tec Triton and Omni Radios

Ten Tec Triton and Omni Power Switches

Can they safely switch 12-volt power?

I was recently asked about the power switch on the Ten Tec Triton IV transceiver. Was it capable of switching the 12-volt line used to power the radio? The short answer is no. Co-located on the volume control, it was intended to switch an external power supply like the Model 252 or 262. Switching the 15 or so amps of 12-volt power needed for the 100 watt transmitter will damage the switch. I’ve seen examples and it’s not pretty. On top of that, replacement volume control/power switch parts are hard to find. 

Switching 12-volts for mobile and emergency power

There is a way to safely switch 12-volt power into the radio for a mobile or emergency power installation however. It’s described in the transceiver’s manual. The secret is to switch an external relay that in turn powers the radio. A “horn relay” or so-called “Bosch” relay is all that is needed.

The technique works on all Triton models, and Omni models A, D and C. I recently added  an Omni C to the shack. But since it is entirely solar powered, I needed a way to switch the radio on and off. There are no other 120-volt power supplies in the shack.

Adding overcurrent protection

Also, the external power supplies for the Triton models provided current limiting to protect the transmitter output transistors. Too much collector current from a mis-matched antenna and the power supply cuts off. I use a fused Anderson Powerpole distribution center (shown above) to provide overcurrent protection.

Simple installation

The circuit is pretty simple, and I’ve provided a version that works in the diagram below. 12-volt power to the radio is interrupted by the contacts of a normally-open relay. One side of the relay coil is connected to 12-volt power, while the other side is connected to ground through the transceiver’s power switch. Voila! Safe switched power.

In the diagram below, 12-volt power is provided to the connections on the left. The four connections on the right side of the diagram match the 4-pin connector on the back of the transceiver. The two outside pins (top and bottom) supply the 12-volt power to the radio. The two inner pins connect to the switch mounted on the volume control. You can see this connector on the back of the radio with a color-coded cable connected in the photo at the top of this post.

I used a “Bosch” relay, commonly used for switching powered accessories in automobiles like headlights, but any 12-volt relay capable of passing at least 20 amps of current will do. Bosch relays are available inexpensively and even have a convenient mounting tab. I used one that is rated for 30/40 amps. Pins 85 and 86 are the relay coil. Pin 30 is contact common, while 87 is normally open contact and 87a is normally closed contact.

The Omni C installation here at WBØMMC

Neat, sweet, hard to beat. With this arrangement, I can safely switch 12-volt power into either a Triton or Omni series transceiver while providing overcurrent protection in the event of an antenna fault. Besides wire and connectors, the only part needed is a relay. Since restoring the Omni C and adding an external digital VFO, I’ve really enjoyed the capabilities of this radio. It hears well. With the optional crystal filters installed,  the receive audio is especially good for CW. It has “presence”  — a quality others have mentioned with respect to Ten Tec radios of this era. Be sure to check out the posts on restoring and adding a digital VFO to an Omni C!