Epic Restoration of a Ten Tec Triton IV – part 1

Getting a Ten Tec Triton IV

eBay has provided a lot of entertainment (and used equipment!) over the last few months, and after the purchase and restoration of a Ten Tec Century 21, I started looking for a Triton IV. As I mentioned in an earlier post, this was the first radio I purchased new in 1978. I really enjoyed that radio and wanted to own one again. It didn’t take long. I ended up having two in the shop at almost the same time — one for my shack, and one for a fellow ham. He wanted me to check it out before he even saw it. As you’ll see, I ended up doing a pretty complete restoration.

It arrived packed in a single layer of thin bubble wrap surrounded by a few styrofoam peanuts. It was shipped in a box that was barely bigger than the radio. I breathed a sigh of relief when I got a look inside and saw that the radio had made it undamaged. There were no crushed corners, and it was fine. Double boxing would have been much better.

First Evaluation

The radio itself was a little rough. It had obviously been used mobile, and the former owner had a power switch mounted in a plastic box and screwed to the side of the radio. Functional, but not pretty.

Ten Tec’s Weird Power Switch

Why an outboard power switch? Early Ten Tec radios didn’t really have a way to switch 12-volt power. Instead, they provided a power switch on the volume control that was intended to control a 120-volt accessory power supply through a 4-wire power cable. Because the radio can draw as much as 20 amps at 12-volts, and the internal power switch was rated at much less than that, Ten Tec recommended an outboard power switch or external 12-volt relay that could be controlled by the internal switch.

Besides the holes in the plastic sides from the switch box, markings had been added in Sharpie to the front panel and some kind of label or name plate had been glued to the top cover. The heat sink had lost much of its black paint, and there was a sheen of nicotine visible on the front panel. I’ll discuss the cosmetic restoration in a later blog post.

A Diamond in the Rough

The good news was that the radio seemed to receive and transmit just fine. Even better, it had the optional CW filter installed. Surprisingly, it did  not have the noise blanker option — that would have been helpful with ignition noise and in the mobile. The receiver seemed sensitive, and the transmitter made 100 watts of power on all bands. Not a bad start.

It did exhibit the sluggish and nearly frozen Permeability Tuned Oscillator (PTO) problem though. The main tuning knob would turn, but with difficulty. I didn’t want to try tuning the radio until this was fixed.

The ever-popular frozen PTO

These early Ten Tec radios are well known for the sluggish or frozen main tuning knob. The recommended fix is to disassemble the PTO, clean out the gummy grease, install a “PTO rebuild kit” and lubricate it with new grease. It’s a challenging process that I described in an earlier post, but the rebuild kits are no longer available from Ten Tec. Hoping to avoid a PTO rebuild, I decided to try a fix recommended on one of the Ten Tec user sites. One comment in the thread suggested dissolving the congealed grease with denatured alcohol applied to the inner and outer shafts. it then recommends turning them until they free up and applying a drop or two of Tri-Flow lubricant to the same parts. I decided to try it,  but with the PTO outside of the radio to gain access to all the greased surfaces. After a couple of applications of the Trl-Flow to several points within the PTO, it did indeed move freely. Not bad.

Testing the Triton IV in the Shack

With the PTO problem resolved, I decided to reassemble the radio and use it for a while. I like to spend time with a radio before making further repairs or alignments because there are often problems that one only discovers with use. So for now, I was done. In the next installment, we’ll tackle the cosmetic improvements to the Triton IV.