[ICOM] Re:ICOM] TX audio on 775

[Bruce]

Igor,
Are you testing into a dummy load? If not I would suggest you try 
that and listen to a
monitor receiver in the shack.
Nothing else hooked up to the radio except mic and dummy load and AC 
power cord?
If you reduce power output does the distortion go away or is it reduced?
If you can look at the RF envelope via a oscilloscope does the wave 
form look clean or
like maybe a bias problem in the PA?
Try disconnecting the Rx jumper in the back of the radio and then re-test.
Bruce

At 12:16 PM 10/16/2006, Igor Sokolov wrote:
>The problem persists with DSP disabled. So it does with the compressor
>disabled.
>
>73, Igor UA9CDC
>
>
>
> > It is possible to disable the DSP in the 775 and have all SSB generation
> > done in analog rather than digital fashion.  Would be interesting to see
>if
> > the problem persists after the DSP is disabled for Tx.  (It can be
>disabled
> > from the front panel menu).
> >
> >
> > ----- Original Message -----
> > From: "Adam Farson" <farson at shaw.ca>
> > To: "'ICOM Reflector'" <icom at mailman.qth.net>
> > Sent: Sunday, October 15, 2006 1:25 PM
> > Subject: RE: [ICOM] Re:ICOM] TX audio on 775
> >
> >
> > > Hi Clete,
> > >
> > > Correction...it is not a compandor; it is a compressor. There is no
> > > complementary expansion function in the receiver.
> > >
> > > In the IC-775 series, the compressor is an analogue circuit in the 455
>kHz
> > > TX IF chain. In the newer IF-DSP-based Icom transceivers (IC-756Pro
> > > series,
> > > IC-7800, IC-746Pro, IC-7000) it is a process in the DSP algorithm.
> > >
> > > I remember the old echo suppressors from my years in the telecom
>industry.
> > > They were analogue, and DSP-based adaptive echo cancellers replaced
>them.
> > >
> > > There is a general article on compression on my website.
> > >
> > > http://www.ab4oj.com/icom/ssbcomp.html
> > >
> > > Cheers for now, 73,
> > > Adam VA7OJ/AB4OJ
> > >
> > >
> > >
> > > Scanned for viruses by Blue Coat
> > > http://www.WinProxy.com/
> > > ----
> > > 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/
>
>----
>Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
>Icom Users Net: Sundays, 1700Z, 14.316 MHz
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