[ICOM] 756PRO3 - popping sound?

[Adam Farson]

Hi Gunnar,

Absolutely. I am sure that even an R&S XK2100L or a Telefunken E1800 has its
idiosyncrasies.

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 Gunnar SM3DVN
Sent: 27-Feb-08 10:36
To: ICOM Reflector
Subject: Re: [ICOM] 756PRO3 - popping sound?

Adam,

The "perfect radio has still to be developed"...

73, Gunnar SM3DVN


----- Original Message -----
From: "Adam Farson" <farson at shaw.ca>
To: "'ICOM Reflector'" <icom at mailman.qth.net>
Sent: Wednesday, February 27, 2008 7:20 PM
Subject: RE: [ICOM] 756PRO3 - popping sound?


> Hi Bert,
> 
> There was a specific problem in the 756Pro which was caused by ripple from
> the noise blanker getting onto the supply rail feeding the audio output
> stages. There was a fix for it.
> 
> http://www.ab4oj.com/icom/756pro_nb/main.html
> 
> This issue was corrected in the 756Pro2.
> 
> I have never heard these popping sounds on my Pro3. The sounds described
may
> also be partially due to artefacts generated by the distant transmitter.
> 
> The choice of AGC attack time in a DSP-based radio is very tricky. In the
> presence of a very strong signal, where the AGC has to slew very fast over
> an extremely large range, some overshoot can occur under certain
conditions.
> This can be minimised by reducing front-end gain (preamp off, attenuation,
> RF gain etc.) and by careful adjustment of the AGC menu. I would certainly
> not regard this as a reason not to purchase the Pro3.
> 
> See also http://www.ab4oj.com/icom/ic7700/agc.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 Bert Almemo
> Sent: 27-Feb-08 05:46
> To: 'ICOM Reflector'
> Subject: [ICOM] 756PRO3 - popping sound?
> 
> Hi guys,
> 
> The following message came in on another reflector. Anyone heard of this
> problem on the PRO3?
> 
> 73 Bert, VE3OBU
> 
> =
> 
> The original Icom 756 Pro receiver had an anoying popping sound that would
> show up at the start of each morse element when listening to strong CW
> signals.
> 
> The 'pop' was mentioned in the QST product review in 2000 as as
> "characteristic of direct conversion receviers employing audio-based AGC
> systesms" and "the pro has a habit of introducing pops on the make of each
> CW element".
> 
> Before purchasing an Icom 756 Pro III, I was told (by Icom) that the
> 'popping' issue was addressed, but that's not the case. The problem still
> exists and is especially obvious with fast AGC settings. It's not too bad
> with the internal speaker, but it certainly shows up with headphones and
> some external speakers.
> 
> Suggestions appreciated...
> 
> No virus found in this outgoing message.
> Checked by AVG Free Edition. 
> Version: 7.5.516 / Virus Database: 269.21.1/1297 - Release Date:
25/02/2008
> 09:22
> 
> 
> ----
> 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/
----
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/


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No virus found in this incoming message.
Checked by AVG Free Edition. 
Version: 7.5.516 / Virus Database: 269.21.1/1297 - Release Date: 25/02/2008
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No virus found in this outgoing message.
Checked by AVG Free Edition. 
Version: 7.5.516 / Virus Database: 269.21.1/1297 - Release Date: 25/02/2008
09:22