> Next, I raised the drive level to 80% of the ALC range
> (Drive control at
> about 1:00)
>
> Icom Setting Measured
>
> 2 ms 0.2 ms
> 4 ms 0.5 ms
> 6 ms 1.1 ms
> 8 ms 1.5 ms
>
> ALC has a profound effect on the IC-7800's CW rise/fall
> time and indeed, on
> most radios.
ALC is part of the power control loop, and is not adjustable
in rigs without a "drive" control.
In the FT1000MP series you can go into a menu and change the
drive setting. I have details on the MKV at
http://www.w8ji.com/ft1000mk_v.htm
I have a question Paul. What ALC level does ICOM say to run
on CW? Do they tell you to barely run the ALC up with the
drive control?
73 Tom
> About eight years ago, I ended up modifying a Ten Tec Omni
> Six after the
> factory "Plus" upgrade. Once distinct difference after
> the upgrade was that
> in an attempt to control a very slight amount of power
> overshoot in the
> original Omni Six, the Plus' ALC was redesigned by the
> factory to completely
> eliminate the power spike. In doing so, the leading-edge
> rise time was half
> of what it was on the original Omni Six. No amount of
> adjusting of the
> internal rise/fall control had much of an effect on the
> leading waveform
> edge. Later Omni Six Plus units eliminated the control
> altogether and fixed
> resistors were used. (i.e., why have a control if it no
> longer works as
> designed?) Take a look at the QST product reviews for a
> comparison between
> the keyed waveform of the Six and Six Plus models. I
> ended up re-designing
> my Plus with a 2-speed ALC circuit that held power spikes,
> yet left the
> ramped waveform intact.
>
> For the measurements above, I am using a microHam CW
> keyer modified with an
> isolated open-collector to +Vcc through a 1K limiting
> resistor for
> triggering an 80 MHz Tektronix SC 504 dual-trace scope.
> This allows me to
> take reasonably accurate measurements without having to
> chase the waveform
> on the screen by changing the time base. My measured
> points are taken at
> the point where the keyed waveform starts taking off and
> ending where full
> output is reached.
>
> Paul, W9AC
>
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