SSB!

I’ve owned a radio with SSB and CW reception at least since I was 17 years old back in 1967, starting with the Lafayette Radio Electronics KT-340 I built from a kit.

I got into collecting shortwave radios a decade or so ago, and some of them had SSB that I don’t remember much about, including the Grundig G4000A, Grundig G5, Sangean ATS-505, and Grundig G3. They’re all sold now. Today I have several different SSB options, and that is the topic of this article.

Acronyms:

• BFO – Beat Frequency Oscillator
• CW – Carrier Wave
• SSB – Single Sideband
• LSB – Lower Sideband
• USB – Upper Sideband
• OSB – Oriented Strand Board

Single Sideband

SSB transmissions are used by amateur radio operators, marine communications, weather broadcasts and commercial radio operations. I’m primarily an international shortwave broadcast listener, but I occasionally listen to SSB, and at least some international broadcasting is on SSB.

A typical AM radio signal consists of a carrier wave that is in the center of the channel, and two sidebands carrying the audio content, one on a lower frequency (LSB) and one with higher (USB). The carrier in the middle carries no information, and the upper and lower sidebands each carry the same information. SSB saves energy by omitting the carrier and one sideband, and saves bandwidth with a channel only half as wide. It’s an elegant scheme, but it takes special equipment to decode it. SSB capability adds to the cost of radio equipment and it adds to the complexity of operation. CW has only the center carrier frequency with no sidebands and the same technology that allows reconstituting an SSB transmission also can generate a tone when detecting CW.

I’ll go over the operational characteristics of each of my SSB-enabled radios, and provide samples of SSB reception on that radio.

Tecsun PL-660

The PL-660 is currently my oldest SSB-capable radio and arguably the best. It’s an analog-tuned and decoded radio with digital frequency display. It uses a BFO to generate the carrier and it’s mixed in to generate the missing sideband. The BFO knob is the center knob on the right side of the radio, with a detent to indicate its middle position. A button selects upper or lower sideband.

Tune the radio in the conventional way for the strongest signal, then turn on SSB, pick the sideband and use the BFO knob to get the generated internal signal at exactly the right frequency. When all is right the garbled SSB sound becomes crystal clear.

My PL-660 is nicely calibrated so that the center BFO setting is usually the best, or very close to it.

If stations are on frequency, tuning is easy and one can just turn on the SSB mode and tune across the band pretty much the same as AM broadcasts. Sometimes getting the BFO setting correct can be frustrating. Usually on my PL-660 the center position of the BFO is the correct one, but sometimes it takes a tiny adjustment; the knob is sensitive and I find it easy to overshoot. It takes practice, but I’m getting better.

This radio and the two other Tecsun models below (the PL-330 and PL-880) allocate separate ATS memory space for SSB stations.

The YouTube videos below are unlisted, meaning you won’t see them in the Blog or Die channel videos list. You’re free to share the links if you want, but they could change.

Tecsun PL-880

The PL-880 came out sometime around 2013. It incorporates analog tuning, but a digital signal processing (DSP) chip decodes the signals. Signal clarity is attained through a fine tuning control rather than a BFO.

In practice, using a BFO and a Fine Tuning control is similar. The advantage to fine tuning on these radios is that the user can read the frequency offset and use it later for other stations. If you know your radio is +180 Hz off, then you may be able to use that same value on every station (perhaps two values, one for LSB and one for USB). The resolution of the fine tuning control in the PL-880’s SSB mode is 10 Hz and that will be the case for the other DSP-based radio discussed later on. The tuning display shows the frequency tuned down to 10 Hz with extra digits on the right of the usual frequency display with the rightmost digit representing 10 Hz.

The PL-880 has one outstanding feature, and that is the ability to calibrate SSB tuning on the radio. Basically the radio can be set so that the “00” fine tuning offset is the one that is on target for SSB. The process is fairly simple: perfectly tune a station and then long-press the SNOOZE button on the top of the radio; the radio saves the value as its new “00” reference. Each sideband, upper and lower, has to be calibrated individually (I think).

Tecsun PL-330

The PL-330 is much newer than the PL-880, but it works in much the same way. It is an all-digital radio with a DSP chip for both tuning and decoding SSB. The main departure from the PL-880 is that a single tuning knob does double duty for both coarse and fine tuning. Having separate dedicated controls like the PL-880 is far more convenient (both for SSB and AM tuning). The PL-330 has a calibration feature too; in this case long-press the LSB button to zero and save the offset.

Eton Elite Executive

The Elite Executive (formerly known as the Elite Satellit) is the successor to a line of Eton/Grundig SSB radios.

The Elite Executive operates very similarly to the Tecsun PL-330, with its main tuning knob doing triple duty as a coarse, fine, and super fine tuning knob. While the PL-330 has a STEP button to select the knob function, the Eton built the switch into the tuning knob itself.

The fine tuning value, also down to 10 Hz, is shown separately on the display, rather than as additional digits on the frequency readout, as a positive or negative value. That’s OK, but the two Tecsuns are easier to read.

The process is the same: find the station, select LSB or USB and then clarify with fine tuning.

XHDATA D-808

The D-808 is rather similar in operation to the Elite Executive in that it shows the fine tuning offset value in a separate area on the display screen. Here, however, there is a dedicated fine tuning wheel on the right side of the radio just below the main tuning knob. Switching between USB and LSB is a done by pressing the Info button.

RTL-SDR Blog SDR with SDRSharp Software

Software-defined radios (SDRs) are a wholly different animal. The “radio” itself is little more than an analog to digital converter with some amplification. The real work is done on a computer.

RTL-SDR Blog makes an entry-level device at a cost less than half that of any of the other radios shown above. The computer software is free. (Computer not included.)

Reception of SSB is more automatic with an SDR. The operator just selects the frequency and the software figures out whether the signal is AM, USB or LSB. But it is still necessary to get the frequency right. SDRSharp can tune to a precision of 1 Hz. In practice, tinkering with fine tuning is still required for the best signal.

Of all the radios in this article, the RTL-SDR Blog did the poorest. There was quite a bit of noise that reducing the bandwidth didn’t solve. We might chalk up this poor performance to my lack of experience with the software.

Synchronous detection

I refer the reader to my earlier article comparing the PL-660 and the PL-880 for information on synchronous detection. Synchronous detection is similar to SSB in that it adds a sideband and carrier to a signal, only in this case the original transmission is AM. Three of the radios here offer a synchronous detection feature: The PL-330, the PL-660 and the Eton Elite Executive. The sync option on the PL-880 is undocumented and works poorly.

Conclusion?

With the exception of the SDR, all the radios sampled did a credible job. With a little tinkering, they all provided very listenable signals. I didn’t attempt receiving very weak signals, and that might have separated the men from the boys. My impression is that the PL-660 did the best job on SSB. Of the remaining examples, the PL-880 was far and away the easiest to use with its conveniently placed fine tuning control (ergonomics matter) and the ability to calibrate the SSB frequency. I know ham radio operators are really picky about how their signals sound, and they might be more critical of my samples than I am, and they would probably have operated the radios better.