[ICOM] 751A

[Steven Moore]

Hi Jim,

The original outfit selling them went out of business. Heil was selling them but I can't find it on his site 
any longer. I heard he discontinued it ? The Heil has some bells and whistles added but I believe it has the 
same board in it.

The clearspeech has such a slight digital sound that you will only notice it for 2-3 days. After that it is 
totally transparent and not watery or hollow. My ears do not detect any loss of frequency response either. It 
will be the last thing to leave my shack.

73
Steve  wd0ct

----- Original Message ----- 
From: "Jim Miller" <JimMiller at STL-OnLine.Net>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Tuesday, September 20, 2005 10:45 PM
Subject: Re: [ICOM] 751A


> 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
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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: http://www.qsl.net/icom/
>