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

[Ed Swynar]

Hi Don,

That's interesting --- just the opposite of what happens here with mine as
power increases...vexxing indeed!

Thanks so much for your input --- appreciated!

~73~ Eddy VE3CUI - VE3XZ





----- Original Message -----
From: "Don" <don1794 at verizon.net>
To: "'ICOM Reflector'" <icom at mailman.qth.net>
Sent: Monday, December 19, 2005 8:10 PM
Subject: RE: [ICOM] IC-751A Key Clicks (Again)


>
> Regarding ICOM-751A keyclicks,
> I set-up my 751A as you asked and with RF drive at minimum the
> ALC reads just above mid scale and slowly decreases to just
> below mid scale at RF maximum.  I don't have key clicks.
> 73
> Don
> KA1A
>
> -----Original Message-----
> From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
On
> Behalf Of Ed Swynar
> Sent: Monday, December 19, 2005 5:10 PM
> To: ICOM Reflector
> Subject: [ICOM] IC-751A Key Clicks (Again)
>
> 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
> ----
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> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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