[Elecraft] K3 and KAT500 low power problems

[Eric Swartz - WA6HHQ, Elecraft]

Hi Emory,

The KAT500 design is optimized for 10W through 1000 W operation, with better 
tuning above 20W. It is not designed as a QRP tuner.  It can be used at 5W 
levels, thought we do not guarantee this, if it is pre-tuned first at higher 
power (20 W +) on each freq and then run in manual mode (which still auto-reads 
the frequency and selects the correct prior tune for that range).  That should 
prevent most false frequency counts at 5W.

Your WSJT power envelope will drop well below its 5W peak during transmission, 
causing the frequency counter to get multiple incorrect counts and generating a 
spurious re-tune when operating in auto-tune mode. The frequency counter in the 
KAT500 works best during regular TX for signals that are primarily peaking above 
the 20W range.

Also, make sure you have the latest KAT500 firmware loaded in your unit. We have 
made significant improvements to the frequency counting and tuning algorithms 
since our earliest shipped units.

Personally, even when running my KPA500 with the KAT500 at 500 W operating 
levels, I use auto-tune mode and 20-50 W to train the tuner to my antennas on 
each frequency with a CW carrier, and then run it in manual mode at 500+ W from 
that point for normal operating.

73,

Eric
elecraft.com

On 11/13/2014 2:30 PM, ejkkjh at gmail.com wrote:
> I have been doing some testing using WSJT-X, and other digital modes, with my K3 an my Signalink USB.
> Receive works pretty good with decodes on WSJT-X at –19 to an occasional decode at –24.
> On transmit using various digital software and modes, when I transmit at 5 watts the KAT500 has problems.
> I tune up with 20 watts, all is fine, 1.0 swr.  But then I transmit with power at around 5 watts, in a digital transmission, the KAT500 starts a tuning cycle, then ends in a fault condition.  If I transmit with the power above about 10 watts, clear up to 100, everything works perfect?
> I have tried this with various modes and digital programs, does it every time, on several different bands.
> I prefer to run at 5 watts but I guess the easy solution is to run at 15 or 20 watts.
> Any help or ideas would be appreciated.
> Thank you 73
> Emory  WM3M
> ______________________________________________________________
> Elecraft mailing list
>