The Ten Tec RX-320 was an unusual but pretty sweet radio. While at the other end of the spectrum from the HF-1000, it shared a similar architecture. Namely, an analog receiving chain followed by DSP. However, it had a radically different price point – about 92% lower!

Personally, I think the folks at Ten Tec just wanted to have some fun. They leveraged their growing capabilities in ham and commercial radio design and, in 1998, released this little gem. I suspect many purists did not take it seriously. I did. And, I was surprised by how well it performed, given its rather sparse interior. This radio had a long run, most recently as a “D” model which made its 12 kHz final IF available for external decoders.

The Ten Tec RX-320 was tailor made for ERGO. Mostly because it had no external controls. Just an RS232 jack to hook up to your computer. Since its OEM software was not that great, many folks wrote control software. For many ERGO 4 users, the RX-320 made for a great, cheap second receiver.

Ten Tec RX-320 Receiver Control

The command protocols for this receiver were mostly ASCII, with a bit of hexadecimal thrown in. The biggest challenge was tuning the frequency. To tune this receiver, the control software had to deal with some complex “tuning factors”. Three oscillators had to be controlled for each frequency and mode:

• First, the front end up-conversion oscillator to get to the 45 MHz IF filter.
• Second, the DSP fourth local oscillator  which moved the signal path from the 455 kHz second IF down to the 12 kHz final IF.
• Third, for some modes, the BFO.

Because of this arrangement and the distribution of filters, I discovered something neat. With a bit of ingenuity, I could use the ERGO software to create functional pass band tuning. I did this by playing around with the “tuning factors”. It worked. ERGO adds PBT, something not included in the original receiver.

Not sure how many people still use this radio, given the wide availability of low cost SDR gear. But for its time, it was ahead of its time, and fun to use.