[ICOM] IC -775DSP vs IC-756ProIII

Adam Farson farson at shaw.ca
Sun Jan 8 02:09:19 EST 2006


Hi Vladimir,

May I suggest that you try to get some "cockpit time" on an IC-756Pro3,
either at a dealer or at a friend's QTH. I also have a lot of information
about the 756Pro series on my website:

http://www.qsl.net/ab4oj/icom/icom.html

I have never had an IC-775DSP, but had an IC-781 in my station. That radio
got me hooked on the spectrum scope as well. In 1998, I replaced it with the
hybrid IC-756 (which had more or less the same DSP as the UI-100 board in
the IC-775DSP). Since then, I have had all 3 Pro models; I acquired a Pro3
last June, from a Vancouver dealer. I do not have the slightest regret at
letting the 781 go; the powerful signal-management tools which an IF-DSP
radio offers have so spoilt me that I shall never go back to an analogue
radio.

Virtually all reproduced sound is "digital" to some degree nowadays. PCM and
DSP are everywhere; one cannot escape them. Wireline and wireless phone
networks, the movies, radio and TV broadcasting, music recording and
reproduction - all now have embedded digital components. Practically the
only "analogue" sound left is live sound. But this does not worry me - as
long as I can understand what the distant operator is saying.

The SSB transmit monitor circuit in the IC-756Pro series taps off a sample
of the 36 kHz analogue transmit IF at the DAC output, feeds it into a mixer
which uses the 36 kHz ADC/DAC clock as an LO, and mixes the resulting
baseband into the main receiver audio chain. The operator thus hears a
precise replica of the transmitted signal as generated by the DSP.

I do not contest (except for Field Day, on other people's gear.) But I have
observed that the IC-756Pro3 handles itself very well in a strong-signal
environment.

Cheers for now, 73,
Adam VA7OJ/AB4OJ



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