[ICOM] 756 Tested

[Adam Farson]

Hi John,

Many thanks for the kind comment - I feel honoured. In general, I set much
more store by my own (and others') operational experience with a radio than
by "numbers' alone - particularly when the IF drives an ADC. 

I had an IC-756 original from 3/1998 until 7/2000. I purchased it because I
was very intrigued by its combination of the proven 781/775 Dual Watch RF
front end with a true, if limited IF-DSP back end. In fact, it replaced my
old 781 because it outran it on weak, noisy SSB signals! My only complaints
were the lack of an IF notch filter inside the AGC loop, and the vertical
sensitivity of the spectrum scope (it was 10 dB shy of where it needed to
be.) I installed the FL-222/223 narrow SSB filter pair in my 756. 

Setting up the IC-756 side-by-side with my old IC-781, and using the same
antenna, I found that by using the DSP-NR (and noise blanker if needed), I
was able to copy and understand weak and noisy SSB signals that eluded on
the 781, even with a JPS NIR-12 DSP unit in the 781' s audio output line.  I
also found that whilst running Icom Net sessions under frequently hostile
band conditions, the 756 seemed somewhat less susceptible to
adjacent-channel cross-mod than the 781. This was especially true with the
narrow filters selected.  I was also working the European 80m DX window at
the time, and found that the IC-756 behaved very well in that crowded
sub-band - especially with the RF preamp off and the narrow SSB filters
selected.

In mid-2000, I replaced the 756 with a 756Pro, which yielded to a Pro2 at
Dayton 2002. I recently acquired a Pro3, which replaced the Pro2. If you are
looking for an IC-756 original, a unit with S/N > 2000 is recommended.

My 756 display never developed any of those infamous blue lines at all. The
new owner, a fellow-member of our local club, has not had any complaints on
that score either.  I did notice that in comparison to that of another
buddy's S/N 1300 unit, my display refreshed very fast and hardly smeared at
all.

Here is a bit of historical speculation on the history of the 756-series
packaging concept:

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

Cheers for now, 73,
Adam VA7OJ/AB4OJ


-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
Behalf Of John Geiger
Sent: 20 August 2005 19:44
To: ICOM Reflector
Subject: Re: [ICOM] 756 Tested

Hi Adam,

You are the Icom Guru when it comes to rigs.  In your experience (on the air
and otherwise), is the Icom 756 original as bad as theW8JI website
indicates?

73s John NE0P

----- Original Message -----
From: "Adam Farson" <farson at shaw.ca>
To: "'ICOM Reflector'" <icom at mailman.qth.net>
Sent: Sunday, August 21, 2005 1:04 AM
Subject: RE: [ICOM] 756 Tested


> Hi Guillermo,
>
> My understanding is that "AIP" is another name for "Preamp In/Out". 
> Yaesu calls it "IPO" (Intercept Point Optimisation". Why they cannot 
> call it a preamp switch escapes me.
>
> The best design approach is a selectable attenuator and a preamp 
> in/out switch. Incidentally, many commercial and military HF receivers 
> do not
even
> have an RF amplifier (preamp).
>
> Cheers for now, 73,
> Adam VA7OJ/AB4OJ
>
>
> -----Original Message-----
> From: icom-bounces at mailman.qth.net 
> [mailto:icom-bounces at mailman.qth.net]
On
> Behalf Of GGLL
> Sent: 20 August 2005 15:18
> To: ICOM Reflector
> Subject: Re: [ICOM] 756 Tested
>
> From the several mails posted regarding the subject, I guess one would 
> expect better results having a preamplifier on-off switch facility, 
> than only have the attenuator (and/or Kenwood's "AIP" switch) with the 
> preamplifier always on, am I correct?.
>
> Best regards
> Guillermo - LU8EYW.
>
>
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> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net Icom 
> Users Net: Sundays, 1700Z, 14.316 MHz Icom FAQ: 
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----
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