[ICOM] 751A

[Jim Miller]

Interesting.  I have often wondered about the claims of the Clearspeach
speaker.  I would like one but just can't seem to let go of that much money
to "try" it.

73, de Jim KG0KP

----- Original Message ----- 
From: "Steven Moore" <scm at copper.net>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Tuesday, September 20, 2005 10:21 PM
Subject: Re: [ICOM] 751A


> This discussion reminded me of the listening noise of a bunch of older
rigs. I going to forget about buying
> the 751a.
>
> I like my 756pro quite well although the nr sounds hollow and the close in
dynamic range seems no better than
> the 950sdx I sold.
>
> I use a clearspeech nr and have for 8 years or so. It is superior to
listen to than any of 8 or 9 hf rigs I've
> owned with nr. I use it 100 percent of my operating time.
>
> 73
> Steve  wd0ct
>
>
> > Hi Blair,
> >
> > Yes indeed - reciprocal-mixing noise manifests itself as out-of-band
noise
> > mixing with the noise pedestal of the 1st LO (synthesiser) to raise the
> > idle-channel noise level in the IF passband.
> >
> > The IC-756Pro series use a very up-to-date DDS scheme which yields
excellent
> > reciprocal-mixing noise numbers. The Pro2 is a little better than the
756Pro
> > in this area, and the Pro3 a little quieter than the Pro2. Even the
> > "original" IC-756 DDS is quieter than any of its PLL-only predecessors.
> >
> > The DSP NR in the 756Pro series improves the S/N at the receiver's audio
> > output even further.
> >
> > Cheers for now, 73,
> > Adam VA7OJ/AB4OJ
> >
> > << The SSB filtering and PBT operation on the 751A was far superior to
that
> > of  its predecessor in my shack . . . . However, I did find that the
751A's
> > PLL  synthesizer was somewhat noisy as compared to newer radios using a
DDS
> > design (-104 dBc/Hz at 2 kHz offset, as compared to -111 for the IC-765
and
> > -125 for the IC-756Pro2). This led to relatively poor close-in
reciprocal
> > noise mixing performance. >>
> >
> > Hi Adam,
> >    Regarding the '751A, you mentioned a noisy synthesizer.  Perhaps that
is
> > what I noticed--something I had had always attributed to a noisy audio
> > chain.
> > A good friend had one which I frequently used.  When he upgraded he
offered
> > the '751A to me at an attractive price.  I thought about it for an hour
and
> > decided against it because of its omnipresent "white noise".  It could
have
> > been unique to that particular radio, but I found that listening to the
> > '751A became very tiring after just a few hours.
> >    FWIW, the '756PRO series [all flavors] seems to lack that
> > (annoying-to-me) "white noise" component.
> >
> > 73,  Blair k3yd
>
>
> ----
> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/