While not really a premium shortwave receiver, my ICOM 756PROII table top was a great way to enter the 21st century of HF radio listening.
As the 1990’s drew to a close, ICOM came out with its 756 series of HF transceivers. A new generation arrived every two years from 1997-2004. I obtained my third generation in 2004. These were the first ICOM transceivers with a 100% DSP final IF stage.
My ICOM 756PROII was a marvel for ham radio and shortwave listening. You immediately fell in love with the colorful real-time band scope, shown above. Although I bought this radio mainly for ham use, I was startled by how well it performed as an SWL table top. The only drawback was fixed filter widths (3, 6, 9 kHz) for AM mode, which worked well. You could also apply IF Shift in AM mode.
This was an amazingly quiet and sensitive receiver in all modes, with smooth tuning and razor sharp filters.
But what hooked me forever was the big spectrum scope on the front panel, which displayed bandwidths up to ±100 kHz. I discovered the scope worked by picking off signals at the 60 MHz first IF and then sweeping these, just like a real oscilloscope. Direct frequency entry and persistent band-stacking were a nice touch, as well.
The ICOM 756PROII table top contained extensive front end filtering, 13 different filters in all, to prevent overload or IMD. Sensitivity was lower for AM BCB and long wave, but I did not find that to be a problem. All in all, a great receiver disguised as a ham transceiver. I wish mine was still working!
ICOM 756PROII Table Top – Under the Hood
So, how did ICOM introduce a complete DSP first IF? Turns out they used a high end 24 bit stereo Cirrus Logic ADC designed for use in audio studios. I am sure this cost a pretty penny when introduced in 1997. My guess is that ICOM probably got an ENOB (effective number of bits) of 16. Not bad for its day.
With 120 dB dynamic range, you could handle all sorts of signals. And sensitive. You could actually hear SSB signals that did not move the S-meter.