[ICOM] IC-751A Key Clicks (Again)

[Ed Swynar]

Hi Frank,

Many thanks for your note --- I shall look into that in my service manual...

~73!~ Eddy VE3CUI - VE3XZ





----- Original Message -----
From: "Frank A. Ellis" <w3uhf at yahoo.com>
To: "ICOM Reflector" <icom at mailman.qth.net>
Sent: Monday, December 19, 2005 6:24 PM
Subject: Re: [ICOM] IC-751A Key Clicks (Again)


> Eddy,
>
> If memory serves, there is a meter alignment step
> called "ALC METER" that correlates the meter to an
> actual ALC/power value. This may be out of adjustment,
> or there could be simply an error in the ALC
> operation.
>
> 73 Frank W3UHF
>
>
>
> --- Ed Swynar <gswynar at durham.net> wrote:
>
> > Good Evening All,
> >
> > I wonder if anyone reading this --- and who owns an
> > Icom 751A --- might indulge me, please, with a small
> > favour...?
> >
> > Specifically, with the rig set-up to transmit in
> > semi-break-in CW, turn the RF drive fully
> > counterclockwise...now, with the meter selected to
> > the ALC position,  hold the key down to send out a
> > carrier. What does your meter show for ALC
> > deflection at this point?
> >
> > Next, gradually turn the RF drive control to maximum
> > (clockwise adjustment) while holding the key down,
> > and observe the ALC deflection in the meter...
> >
> > If your rig is like mine, you will have seen a good
> > half-scale deflection, or more, in ALC with low
> > power output, & then even more ALC at maximum
> > output.
> >
> > This confuses me: I always believed that ALC was not
> > activated until such time as an overdrive condition
> > was approached...in the low power setting of the RF
> > drive control, why would there have even been an ALC
> > indication? On my Yaesu FT-980, there is NO ALC
> > meter movement whatsoever until the 100-watts of
> > specified output is approached, or exceeded --- the
> > 751A starts out high in ALC from the get-go!
> >
> > In fact, the Yaesu manual cautions the operator that
> > generation of key clicks may well result at the
> > point of ALC meter deflection...
> >
> > What got me thinking of this was reference in an
> > 80's issue of QST magazine --- a fellow therein
> > stated that improperly "...thresholded" ALC can, and
> > does, contribute to the generation of key clicks in
> > modern transceivers...
> >
> > Many thanks for any & all assistance & observations
> > in this regard with your own 751A...
> >
> > ~73~ Eddy VE3CUI - VE3XZ
> > ----
> > 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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