Odyssey of Argonauts

QRP Community: The Odyssey of the Argonauts

By Anthony A. Luscre, K8ZT

Contributing Editor

April 29, 2003

With the recent introduction of Ten-Tec's Argonaut V, let's explore the entire family of Ten Tec's premier low-power radio-- the Argonaut and its relatives.

According to Bulfinch's Mythology, in ancient Greece:

[I]t was suggested to Jason that he undertake the glorious adventure of going in quest of the Golden Fleece. Jason was pleased with the thought and forthwith made preparations for the expedition. At that time, the only species of navigation known to the Greeks consisted of small boats or canoes. When Jason employed Argus to build him a vessel capable of containing fifty men, it was considered a gigantic undertaking. It was accomplished, however, and the vessel was named Argo, from the name of the builder. Jason sent his invitation to all the adventurous young men of Greece and soon found himself at the head of a band of bold youths, many of whom afterward were renowned among the heroes and demigods of Greece. They were called the Argonauts, from the name of their vessel.

Similar to the Argo's simple predecessors, the Ten-Tec Argonaut radio series predecessors consisted of small homebrew and kit QRP radios (often single-band, separate transmitters and receivers and CW-only.) The first Ten-Tec Argonaut was a QRP milestone that combined receiver and transmitter into a solid state, CW and SSB, multiband transceiver package.

The travels of Jason's Argonauts' were an odyssey--a long wandering or voyage usually marked by many changes of fortune. The Ten-Tec Argonaut series has also been an odyssey, with five generations and a few tangential relatives. This month's column will explore the Argonaut line and its lineage.

In 1968, Al Kahn, K4FW, and Jack Burchfield, K4JU, founded Ten-Tec. In 1969 the company produced a series of modules that hams could use as building blocks in assembling a solid-state low-power (ie, QRP) CW radio. These modules also were used as the basis for Ten-Tec's "Power Mite" (PM) series of solid-state CW transceivers. The PM series was available in three main models (PM-1, PM-2 and PM-3). Variants included additional bands and features.

The Argonaut Models 505 and 509

Ten-Tec introduced the first Argonaut in 1971 (see "The Second Coming of the Argonaut" CQ, Nov 1971). The exterior featured an eggshell-white front panel, black lettering and wood-grain laminate top and side panels. Later described as the Argonaut Model 505, the rig was quite an accomplishment for its era. The Argonaut 505 offered all-solid-state design, CW and SSB, 80-10 meter coverage, full break-in keying (QSK), a compact package (HWD 4½x13x7 inches) and the ability to operate from a 12-V battery. Power output was 3 and the retail price $288. 

Construction featured plug-in modules for each section of the transceiver. The receiver was a single-conversion 9-MHz IF superhet design using dual-gate MOSFETs, a four-crystal cascade lattice filter.

The VFO was designed around a permeability-tuned coil oscillator (PTO). As the user changes frequency, a threaded shaft moves a powdered-iron core into or out of a coil. This changes the inductance of the coil and, thus, the frequency. 

The RF power amplifier was a broadband design that required no tuning as the user changed bands--a concept almost unheard of in radios of that age. Ten-Tec's advertising summarized it as "all the features you want in a 6-pound package of 1/5 cubic foot."

Its successor, the Argonaut Model 509, debuted in 1973, looked almost identical to the original Argonaut 505. Enhancements included a "hotter" receiver. The retail price was $329. The Argonaut 509 was manufactured in substantial quantities and can be a very good used choice for the beginning QRPer. Used prices typically range from $150 to $275, depending on condition.

The Argonaut Model 515

The third Argonaut, the Model 515, debuted 1978. Although essentially identical in size from its predecessors, there was a major departure in appearance. The Model 515 sports an all-black case and front panel. Ten-Tec touted new and improved front-end sensitivity, VFO/PTO and an indicator light for RIT (receiver incremental tuning) operation.

Ten-Tec divided the 10-meter band into four 500-kHz segments, in part for easier tuning of this wide band. Retail price was $429. The Argonauts 515 remains prized by QRP enthusiasts and Ten-Tec collectors alike. Because fewer than 800 of these units were made, however, the price of a Model 515 on the used market can approach or even exceeds the new purchase price.

The 515 was my first radio in 1981 when I got my ham ticket. Although I have owned many much more sophisticated and expensive rigs since and only use it occasionally these days, it's still a pleasure to operate.

For potential used-radio buyers, all three of the first-generation Argonauts can provide a reliable and inexpensive introduction to QRP on CW and SSB.

Two items may need maintenance on these rigs. The first is the main dial cord. The cord has an elastic portion that ages and stretches over time. Symptoms of this problem include a drooping dial pointer or uneven movement. Replacement dial cords remain available from Ten-Tec and are very inexpensive. The replacement job is not difficult, but it is time-consuming because you have to remove all the knobs and the entire front panel. The other problem is the "sticky PTO syndrome" as the lubricant used in the PTO mechanism hardens over time. A repair kit is available from Ten-Tec.