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

[Frank A. Ellis]

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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