K3 SSB +CW Power Overshoot

Posted by Elecraft mailing list on May 28, 2018; 4:44pm
URL: http://elecraft.85.s1.nabble.com/K3-SSB-CW-Power-Overshoot-tp7641319.html


I have just attempted the K3 SSB +CW configuration for the first time. 
 Unfortunately, behavior is not quite as expected; I experience a
 substantial CW carrier overshoot on first key press and after a subsequent
 mode change. (Mode change can be a band change or an Operate/Standby
 change when running with the KPA500). 

 The overshoot is on the order of 10 to 40% depending on the power level
 setting. 

 When running the K3 barefoot at 100 watts the overshoot is on the order of
 110 watts measured with a W2 in peak reading mode.

 When running the KPA500 set for 500 watts (approx 27 watts drive), the KPA
 output overshoot has been observed to exceed 700 watts triggering a high
 power fault. The only recourse is to reduce drive setting to the KPA500 to
 an output level of 400 watts or so where the output power overshoots to on
 the order of 550 watts.

 Holding down the key after the overshoot, the power settles to the selected
 value in a second or so (assuming KPA power is set such that no fault
 occurs). 

 Subsequent CW key presses produce power output at the selected value without
 overshoot, regardless of momentary or continuous key press. 

 Also observed is difficulty setting power on key down, particularly with the
 KPA500. Power setting is "jumpy" when changing power, after the overshoot
 has stabilized. It seems as if when increasing power, it overshoots the set
 value, then drops to the set value.

 The issue is observed on all bands and on upper or lower sideband.

 I've performed TX Power Calibrate several times with reported success, but
 no change in overshoot behavior.

 When in normal CW mode, there is no overshoot and the power adjustment is
 smooth and stable.

 The SSB +CW mode would be quite useful if it was stable, but I am uneasy
 using it as currently implemented. Any comments or ideas are welcome.

 K3 is S/N 4457
 Firmware version is 5.62
 FPF 1.26
 DSP 2.88

 73,
 Dan AC6DM

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]