[Elecraft] KAT100 LEDs Gone Wild

[Jack Brindle]

Roy;

Try adding several feet of coax between the tuner and the antenna and  
try again. It appears you may have a voltage maximum occurring at the  
tuner - adding the coax will move it out a ways. There are just some  
impedances and feedline lengths that tuners have a difficult time  
handling. If, by chance the antenna is open-wire fed, then add coax  
between the KAT100 and the balun...

Note that the Bird will see different line characteristics than the KAT  
because it has a different placement in the line, and thus different  
voltage/current values at that point. It is the values at the tuner  
that are critical, because they are what the tuner's LC circuits have  
to match.

One other thing - the K2 gets the SWR from the KAT, so if the KAT's SWR  
display is changing, the K2's SWR display should also be changing.

If all else fails, make a video of the display and advertise it on  
late-night TV. Late-night viewers will buy anything these days, and you  
just might get rich doing it!

On Nov 20, 2004, at 8:22 AM, Unifiedtx at aol.com wrote:

> I thought that installing MCU1.05 there would be ample RF sampling  
> rates
> taken to avoid erratic LED displays.  The updated firmware seems not  
> to be  the
> solution.
> With a 50 ohm dummy load on the KAT100 output only the leftmost LED  
> lights
> up and K2 SWR is 1:1 regardless of power or band in use.  With the  
> Carolina
> Windom 80 attached to the KAT100 output and a Bird 43 wattmeter  
> between the K2
> output and KAT100 input, I found the reflected power stayed at zero  
> and the
> forward power stayed at max (regardless of band or power setting)  
> while the
> KAT100 LEDs and K2 SWR reading were going wild.  The wildest LED and  
> SWR
> activity occurs on 30 meters but does not occur on all bands.
> I have already removed the white wire from pin 7 of the K2 end of the  
> IO
> port and put a .01 pF cap from the white wire to the bare wire on pin  
> 1.
> My shack is on the second floor (over my garage) and I have tried to  
> be as
> attentive to grounding as possible.  I use a common grounding point  
> that
> attaches to a 1/2 " copper pipe (used only for grounding) that goes  
> down approx  10
> feet to an eight foot buried grounding rod.  I believe the K2 erratic   
> SWR
> activity will stop when the KAT100 LED stray RF problem has been   
> eliminated.
> Has anyone made any changes or done any bypassing inside the  KAT100 to
> eliminate stray RF and tame the LED display?  Roy Morris   W4WFB

- Jack Brindle, W6FB, ex-WA4FIB
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