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KAT100 LEDs Gone Wild

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Unifiedtx

KAT100 LEDs Gone Wild

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
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Don Wilhelm-3

Re: KAT100 LEDs Gone Wild

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: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
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> Elecraft web page: http://www.elecraft.com
>

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Jack Brindle

Re: KAT100 LEDs Gone Wild

In reply to this post by Unifiedtx

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, [hidden email] 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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MC Carpenter

Re: KAT100 LEDs Gone Wild

that did it, thanks
----- Original Message -----
From: "Jack Brindle" <[hidden email]>
To: <[hidden email]>
Cc: <[hidden email]>
Sent: Saturday, November 20, 2004 2:05 PM
Subject: Re: [Elecraft] KAT100 LEDs Gone Wild

> 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, [hidden email] 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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