[ICOM] IC-7000 AM Modulation Problem

[Larry Harrison]

Hi David.

The modulation takes place in DSP. It could be the way the 7000's DSP 
algorithm generates AM.
It does not matter how hard you hit the audio, you only get 30% modulation 
on voice.

Many others have reported the same problem.

I also emailed Rob Sherwood of Sherwood Engineering, Inc. to find out if he 
by any chance had tested the IC-7000 AM modulation.  Rob said he had tested 
the IC-7000 and also found only 30% on voice and 100% on tone.

Seems we all are up against a stone wall. ICOM alleges that the 7000 meet 
their specifications and refuses to even acknowledge the problem.

In an email back to me ICOM stated :

on 03/30/2006
"The attached picture is from the testing that we did. You can see with the 
HM-103 held of to the speaker of the monitor the radio is almost modulating 
at 100%. If the meter in the upper left was at the 12 o'clock position that 
would be 100% modulation." (WITH A TONE NOT VOICE)

on 04/01/2006
"We did try testing the modulation of the radio with voice. According to our 
technicians when they modulate with voice they see what they would expect to 
see. They said that the radio is functioning fine and performing to the Icom 
specifications."

"they see what they would expect to see" (This can mean anything from 0% to 
100%.  This is a vague and non answer.)

Go Figure!

73,
Larry K3JRR



----- Original Message ----- 
From: "David J. Ring, Jr." <n1ea at arrl.net>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Friday, April 07, 2006 05:53
Subject: Re: [ICOM] IC-7000 AM Modulation Problem


> Hi Larry,
>
> I was reading your posts - and I have a couple of questions.  Forgive me 
> if
> you've already answered them.
>
> You mention that you modulated your AM signal with a tone, and it 
> modulated
> 100%.
>
> But with voice only 30%.
>
> That is really puzzling!
>
> Have you tried feeding an audio amplifier (at microphone level plus 15 dB)
> into the microphone connection?  Or perhaps going into the rear AUX "din"
> connector (I don't have that model, but other recent ICOM's have this.).
>
> I'd make a tape recording with my voice hitting 0 VU and then with a tone
> hitting 0 VU and feed it into the microphone connector - then the AUX
> connector.  Of course the modulation "should" peak the same - unless the
> TONE control is set differently to favor one or the other.
>
> This is too strange!
>
> 73
>
> David N1EA
>
>
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