Amazingly Good-Sounding SSB (ESSB)

by Kevin Strom, WB4AIO

TO PROVE THAT STANDARD AM (a mode that is very close to my heart) isn’t the only HF mode offering good fidelity these days, here’s a 10 MB mp3 audio file I recorded (with one of the Flex SDR-1000s  I’ve been experimenting with lately) Labor Day evening of some ESSB operators on 3630 kHz. The band hadn’t completely formed yet, as these Central Daylight Time fellows were propagating to the East Coast at about 7:30 pm their time — full daylight. And static from the remains of Hurricane Isaac was very much present. Yet these only moderate strength signals — some just equal with the static crashes — are still quite intelligible. I think the good intelligibility is because of the wide broadcast-style frequency response, not in spite of it.

It’s amazing what excellent sound some of these experimenters are getting out of single sideband. For years — decades really — only (highly modified to broadcast standards) AM gear was getting this kind of audio quality on amateur radio. But improved techniques have really made SSB sound better than ever!

For best results, listen on a high fidelity set of speakers or headphones:

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WA3VJB and W3GMS on 40 Meters

by Kevin Strom, WB4AIO

HERE’S an mp3 of Paul, WA3VJB the other day on 7290 kHz as heard on my Racal RA6790/GM in its widest — 20 kHz — bandwidth.

Although my urban Charlottesville location adds some noise and my receive-only antenna is far from optimal, Paul’s Collins 300G still impresses with its round, dense, satisfying sound. It’s not often I get to use the 20 kHz filter. And it is great to hear a transmitter that I worked on many years ago (when it emitted 1 MHz waves instead of 7 MHz ones) on the air again and sounding better than ever.

WA3VJB on 7290 – wide bandwidth on Racal RA6790/GM”]

And here’s another recent 7290 recording — this one of Joe, W3GMS.

Although a local plasma TV created some interference, the fantastic down-to-almost-DC frequency response of Joe’s rig (that makes any speaker sound better than an original Advent) comes through great in the Racal’s 20 kHz position.

[wpaudio url=”″ text=”W3GMS on 7290 – wide bandwidth on Racal RA6790/GM”]

The Racal’s synchrodyne AM detector is very interesting and reasonably high fidelity (as long as the AM station being received does not hit the 100% modulation baseline). I have modified the audio and AGC circuits in the Racal for better audio quality; they are a work in progress.

Out of the Past: WB4AIO on ‘AM-ology’

by Kevin Strom, WB4AIO

THANKS TO an anonymous listener and the Audio Vault at, we now have a audio clip of my AM station, recorded while I was living in Rochester, Minnesota in 1996.

At the time I was running my highly modified Kenwood TS-440s on 75 meters into an Alpha 77D at about 300 Watts into a 150′ inverted L antenna that just barely fit into my small city lot. (All that gear is now gone — stolen from me along with nearly everything else I owned.)

The signal isn’t bad considering that it was presumably heard a thousand miles away on the East Coast. You can hear the recordist adjusting the bandwidth (sounds much better in the wide mode) during the segment. I’m discoursing on ‘AM-ology,’ a field which certainly deserves further study!

Listen to WB4AIO on ‘AM-ology’ (1996 from Rochester MN)”]

Flex Radio Users Net

Power SDR screen shotsby Kevin Strom, WB4AIO

I’VE JUST DISCOVERED a new and worthwhile amateur radio net, meeting Saturday mornings on or around 3872 kHz in the AM mode. It’s the Flex Radio Users Net, devoted to discussions of the software-defined transceivers manufactured by Flex Radio Systems and related topics.

Flex Radio Users Net – 2 January 2010 – 3872 kHz”]

This week, the group was discussing both the theoretical and practical aspects of symmetrical versus asymmetrical modulation, modulation levels generally, and audio processing for HF amplitude  modulation transmission.

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Amateur Radio Audio Recordings

The TEAC-3340S, the model which was the main WB4AIO recording deck for many years, before it was stolen along with everything else I owned in 2006. Today I use Cool Edit Pro to make most of my recordings.

The TEAC A-3340S, the model which was the main WB4AIO recording deck for many years, before it was stolen (along with virtually everything else I owned) in 2006. Today I use Cool Edit Pro (a PC-based audio suite) to make most of my recordings.

by Kevin Strom, WB4AIO

I’VE JUST added two sections to, one appearing in each sidebar, showcasing some interesting amateur radio audio recordings. Make sure that javascript is enabled in your browser for this site, and you’ll see a list of recordings with a small arrow on the left of each listing. Click on the title or the arrow, and a small player will open up, allowing nearly instant playback of the file. Click anywhere on the progress bar to skip around, and right-click the ‘download’ link which appears during streaming if you want to save the file to your hard drive.

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