[Elecraft] KAT100 LEDs Gone Wild

[W3FPR - Don Wilhelm]

Roy,

Getting a really good RF ground for a 2nd story shack may require more than 
a 1/2 inch copper pipe, it may be a good ground at DC, but actually may have 
a high impedance at RF (depends on the frequency).

The easiest thing to try is a quarter wave counterpoise wire (open at the 
far end and out of the way - that end WILL have high voltage RF on it).  Cut 
one for each band (fan out the ends).  The wire can be stretched out on the 
floor is necessary, but neater and safer if it is run outside.  If you can 
get it in a straight line, so much the better, but not a requirement - but 
do make gentle bends (radius of a large coffee can) if you cannot run it 
straight.

The characteristics of a quarter wave wire apply - high voltage RF on one 
end and zero volts on the other.  The zero volts end is a good RF ground 
point - connect it directly to your KAT100.

73,
Don W3FPR

----- Original Message ----- 

>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
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.): 
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>