Topband: Key Clicks

[Paul Christensen]

> The clicky rig was an Icom IC-7800.  The factory default menu setting is
> clicky.  You IC-7800 owners should set the menu item for CW rise time to
> max to get rid of your clicks. 73, de Earl, K6SE

Key clicks coming from the 7800 are almost surely the result of ALC 
overdrive -- which can produce a hard leading-edge   The 7800 incorporates a 
front panel "Drive" control.  Proper setting in CW is to ensure that drive 
occurs at the ALC threshold and no more.  If the drive is adjusted into the 
ALC limiting range, the 7800 is certainly capable of producing objectionable 
key clicks.  But if drive is properly adjusted, keying is exceptionally 
clean.

It's the classic case of trying to design a radio with a fast enough ALC to 
prevent leading-edge power spikes when power is adjusted for less than 
maximum, but not so fast as to desecrate the leading edge of the transmitted 
waveform.  At least Icom provides this control on the 7800.  Most other 
radios are designed with "compromise" ALC circuits.

Paul, W9AC