Enhanced Single Side Band is a way to make your TX-audio sound like professional AM-broadcasts. For ESSB a minimum bandwidth of 3k is needed, instead of the usual standard bandwidth of ~2.3k. I use a Kenwood TS-870S, still the best out-of-the-box tranceiver for ESSB due to it’s variable DSP IF-bandwidth filter on TX (max 3k) and RX (max 6k).

19ut003 ESSB | Zoom H2 + Kenwood TS-870SNot so long ago I experimented with a Zoom H2 recorder (first model) on my TS-870S. The H2 is a very interesting stereo/surround pocketsize audiorecorder with four built-in mikes of outstanding quality. I connected the line-out of the H2 with the mike-input of the 870 (not the acc), with only a non-axial high quality capacitor of 10 uF/63 V in series with the signal and the mike-in on the 870 is bridged to GND with a 1000 Ohms resistor.

The mike is powered by an ajustable regulated powersupply. When the H2 is left switched on you only have to power-up the supply for it to work. I tweaked the settings of the H2 (stereo to mono, speach = agc 2, no low-cut, volume 50, monitor on) and on the 870 (TX EQ HI, TX-bandwidth 0-3000 Hz, mike agc 1, mike vol. ~3.5).


What a surprise this little gem – the H2 – had in store for me. I used to work for an international shortwave radiostation, and a radiobuddy told me my TX-audio on the 870 sounds like when I was on air during professional AM broadcasts. I never thought 3k bandwidth could sound so good. The Zoom H2 also performs great on FM and even with full TX-power (~120 Watts on my indoors antennas) there are no problems with RFI. I only use ferrite at all in- and outputs to choke possible RF interference. Not even a galvanic separation for the input is needed, but a (double) windscreen is a must have to reduce wind overload on the Zoom H2.

After fooling around with all kinds of audio equipment, the Zoom H2 is my microphone. And very important: A very affordable option for wonderful rich-sounding ESSB transmissions!

– If you’re interested in ESSB, visit the X-TREME ESSB AUDIO FORUM for more info.



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