[Icom] Extensive 756 Pro II Review

[George, W5YR]

Andy, I just finished the review and am, to put it mildly, astounded at the
guy's "findings" re the PRO II.

Now, I have used only the "old PRO" but I find none of the gripes he
mentions. The most glaring discrepancy that I find has to do with his
perception of audio receive distortion. I do not know what he listens with
or how or what condition his hearing is in, but I do not share his
conclusions at all. The PRO has probably the best SSB and AM receive audio
that I have heard in an amateur receiver since the post-WW2 days of the big
old Nationals with their built-in 10-watt p-p 6L6 audio amps!

I operate the PRO daily side by side with the IC-765 as my "other" radio,
and frankly the audio from the 765, played through exactly the same audio
system as with the PRO, sounds so bad on SSB that I rarely can stand to
listen to it. For CW it is superb. but not for SSB. I also use the Kachina,
architecturally very similar to the PRO, but its receive audio is far from
as clean and wide-range as the PRO. 

For those who are interested in such things, take a look at Adam's web site
on the Icom pages and look for Passband. There you will find spectra that I
made of the IF/audio response of the 765 and the PRO at all settings and
modes. The spectra clearly show why the 765 sounds so bad on SSB. The
Kachina is a slight improvement, but lacks the same low-frequency response
as the 765. 

I take PRO receive audio out at line level from the ACC1 connector and feed
it into a Behringer MX602A mixer/EQ for level setting and EQ if desired,
and then feed the signal into a 65 watt/channel stereo amp into a large
stereo cabinet with excellent speakers. 

With that setup I can hear 20 Hz audio in the shack from beatnotes in the
PRO and can shake the furniture at 30 and 40 Hz. By spectral estimates made
with SpectroGram and noise excitation, my PRO is *flat* from about 80 Hz to
3100 Hz and is down 6 db at 60 and 3600 Hz. Viewing the audio output on a
scope of the PRO tuned to an AM broadcast station in USB mode and then
detuned to get a beatnote, I can see what appears to be a perfect sine wave
output from about 20 Hz to as high as the filters will go - 3600 Hz. The
transmit audio bandwidth is from 30 Hz (55 watts) to about 2950 Hz (30
watts) again with a clean recovered sine wave.

So, I have to disagree in terms of my own experience with my PRO over the
past 1-1/2 years of daily operation with respect to audio quality,
transmitting or receiving. I have never gotten a report of transmit audio
quality less than excellent, and the gang on 14178 generally sound like
broadcast stations.

The other negative points in the review seemed to me of interest only to
the dedicated SWL enthusiast - I found nothing that I could identify with
my experience using the PRO for amateur radio and very rare occasions as an
SWL receiver. I routinely use Preamp 1 on all bands at all times. Only when
my contesting neighbor about a mile away fires up his "big rig" am I aware
of any overloading problems and that is with the S meter reading S9+60-70
db. Usually taking out the preamp and cranking in a little Attenuation
allows me to copy stations within a few KHz of his frequency. I
occasionally use Preamp 2 on 10 meters as well.

I do appreciate the time and effort the gentleman put into the report and I
suspect that he was sincere in calling the shots as he saw them. I was
gratified to see that he presented the links to Adam's website for perhaps
another viewpoint and certainly as a source of technical information.

Thanks, Andy, for asking my opinion. I wonder now how many people will
agree with my assessment both of the review and my own observations?

72/73/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771
Icom IC-756PRO #02121  Kachina #91900556  IC-765 #02437

All outgoing email virus-checked by Norton Anti-Virus 2002


awallacejr@charter.net wrote:
> 
> Very weird review and seems to contradict all other advice about minimal use
> of the PRO pre-amp to get maximum receive sensitivity. I don't think this
> guy likes Icoms, period. Recent articles in ham magazines regarding DSP
> radio tuning for maximum sensitivity contradict this guy's approach. Who is
> correct?? :-)  George?  Adam? thoughts? No preamp or "at least preamp 2"?
> With my Pro, I seem to be able to get clearly readable SSB audio when the S
> meter doesn't move at all and I'm not sure what signal report to give :-)
> 
> Andy  K5VM