I recently got rid of an Icom 756 in favor of the Omni VI Opt.3.
Side-by-side comparison showed that the Omni VI has a definite edge in
weak-signal reception. The difference may be attributable to lower phase
noise in the Omni VI. The 756 DSP wasn't up to snuff clarifying mushy, noisy
signals. The Omni VI DSP seems to work better. The IC-756 could never hear
weak signals in the "holes" in between strong stations, where the Omni VI
picks up some nice activity.
The PBT is different - in the Omni VI you can lose the station if you don't
retune the frequency when the station gets out of the passband. In the Icom
radios (I also had an Icom 740) passband tuning doesn't shift the center
frequency.
In fact, my Omni-C beats the IC-756 in weak-signal work, except the lack of
PBT makes it harder to dig out weak signals in between strong stations.
73, Meir WF2U
Landrum, SC
> -----Original Message-----
> From: tentec-bounces@contesting.com
> [mailto:tentec-bounces@contesting.com]On Behalf Of DennisKT5D@aol.com
> Sent: Sunday, December 19, 2004 5:19 AM
> To: tentec@contesting.com
> Subject: Re: [TenTec] Omni 6 sensitivity
>
>
> I had an Icom-765 for awhile which sported a very good
> receiver comlete
> with all the filters for cw work. It had the PBT and IF shift
> mods done as well.
> I sat it down beside the Omni 6+ and did some testing. Ambient
> noise level on
> both was almost identical with perhaps the edge to the 765. At
> the time the
> 765 was matching up with some plans I had for reconfiguring the
> shack so I was
> about to decide to sell the Omni 6+. Then the CQ WW CW DX contest
> came along.
> After A/B comparison during the contest, I abruptly changed my mind about
> reconfiguring the shack and selling the Omni.
> What I discovered was this. I could tune between two strong US
> stations a
> couple of kHz's apart with the Omni and copy a weak DX station, 3 to 4
> s-units, easily. Switching to the 765, I absolutely could not
> hear the weak DX
> station. All I heard was an elevated noise floor due to the close
> in strong US
> stations. Clearly, to my ears the Omni is the superior contest
> rig of the two. The
> 765 could hear as well as the Omni in non-contest conditions so
> sensitivity
> was not an issue. Both radios exhibited the high pitched hiss on
> white noise
> but again, the 765 wasn't quite as bad as the Omni. The
> selectivity was what
> really separated the two radios in contest performance.
> If your radio doesn't seem to be as sensitivity as it should
> be perhaps
> there is a problem with it. The Omni's reputation is well earned
> here and the
> 765 is gone.
>
>
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