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[K3] KAT3 and 160 with 40m long doublet

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Don Wilhelm-4

Re: [K3] KAT3 and 160 with 40m long doublet

Wes,

I don't know about the -j501, but Kirchoff tells me that a series Xl =
j1000 alone will cancel the +j1000 in the shack feedpoint (your example)
leaving a 50 ohms pure resistive load, no need for the shunt element.

Since the absolute value of the Low Pass L-net impedance requires that
Rl be less than Rs, I do not know how a Low Pass section would provide a
match. The matching section must be a High Pass with your values.

73,
Don W3FPR

On 1/2/2011 10:22 PM, Wes Stewart wrote:

> Sort of sounds logical.... but it's wrong.
>
> Let the load in the shack be 50 +j1000.
>
> A low-pass L-net with a shunt Xc = -j501 and series Xl = j1000 will do it.
>
> Wes N7WS
>
> --- On Sun, 1/2/11, Don Wilhelm<[hidden email]> wrote:
>
>> As you mentioned, the matching range of the KAT3 becomes
>> greater as the
>> frequency is increased.
>> That fact is often overlooked by many hams. It is all
>> about the amount
>> of L and C available in the tuner, but the inductive or
>> capacitive
>> reactance is really what counts in producing the
>> match. If the
>> feedpoint in the shack has 1000 ohms of inductive
>> reactance, and the
>> tuner has only 600 ohms capacitive reactance to attempt to
>> cancel that
>> inductance, then a match will never happen.
>
>
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Stephen Prior

Re: [K3] KAT3 and 160 with 40m long doublet

Many thanks, gentlemen, for the many words of wisdom.

The topic, so far as I am concerned at least, is now closed!

73 Stephen G4SJP

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n7ws

Re: [K3] KAT3 and 160 with 40m long doublet

In reply to this post by Stephen Prior

Don,

So you want to add +j1000 to +j1000 to get zero?

Wes

--- On Sun, 1/2/11, Don Wilhelm <[hidden email]> wrote:

> Wes,
>
> I don't know about the -j501, but Kirchoff tells me that a
> series Xl =
> j1000 alone will cancel the +j1000 in the shack feedpoint
> (your example)
> leaving a 50 ohms pure resistive load, no need for the
> shunt element.
>
> Since the absolute value of the Low Pass L-net impedance
> requires that
> Rl be less than Rs, I do not know how a Low Pass section
> would provide a
> match. The matching section must be a High Pass with
> your values.
>
> 73,
> Don W3FPR
>
>
>
> On 1/2/2011 10:22 PM, Wes Stewart wrote:
> > Sort of sounds logical.... but it's wrong.
> >
> > Let the load in the shack be 50 +j1000.
> >
> > A low-pass L-net with a shunt Xc = -j501 and series Xl
> = j1000 will do it.
> >
> > Wes N7WS
> >
> > --- On Sun, 1/2/11, Don Wilhelm<[hidden email]>
> wrote:
> >
> >> As you mentioned, the matching range of the KAT3
> becomes
> >> greater as the
> >> frequency is increased.
> >> That fact is often overlooked by many hams.
> It is all
> >> about the amount
> >> of L and C available in the tuner, but the
> inductive or
> >> capacitive
> >> reactance is really what counts in producing the
> >> match. If the
> >> feedpoint in the shack has 1000 ohms of inductive
> >> reactance, and the
> >> tuner has only 600 ohms capacitive reactance to
> attempt to
> >> cancel that
> >> inductance, then a match will never happen.
>

Don Wilhelm-4

Re: [K3] KAT3 and 160 with 40m long doublet

Wes,

It was late last night and I misinterpreted the sign - so yes, that was
what my eyes at that time did to me.
Your solution is more correct in the light of day.

73,
Don W3FPR

On 1/3/2011 9:06 PM, Wes Stewart wrote:

> Don,
>
> So you want to add +j1000 to +j1000 to get zero?
>
> Wes
>
> --- On Sun, 1/2/11, Don Wilhelm<[hidden email]> wrote:
>
>
>> Wes,
>>
>> I don't know about the -j501, but Kirchoff tells me that a
>> series Xl =
>> j1000 alone will cancel the +j1000 in the shack feedpoint
>> (your example)
>> leaving a 50 ohms pure resistive load, no need for the
>> shunt element.
>>
>> Since the absolute value of the Low Pass L-net impedance
>> requires that
>> Rl be less than Rs, I do not know how a Low Pass section
>> would provide a
>> match. The matching section must be a High Pass with
>> your values.
>>
>> 73,
>> Don W3FPR
>>
>>
>>
>> On 1/2/2011 10:22 PM, Wes Stewart wrote:
>>> Sort of sounds logical.... but it's wrong.
>>>
>>> Let the load in the shack be 50 +j1000.
>>>
>>> A low-pass L-net with a shunt Xc = -j501 and series Xl
>> = j1000 will do it.
>>> Wes N7WS
>>>
>>> --- On Sun, 1/2/11, Don Wilhelm<[hidden email]>
>> wrote:
>>>> As you mentioned, the matching range of the KAT3
>> becomes
>>>> greater as the
>>>> frequency is increased.
>>>> That fact is often overlooked by many hams.
>> It is all
>>>> about the amount
>>>> of L and C available in the tuner, but the
>> inductive or
>>>> capacitive
>>>> reactance is really what counts in producing the
>>>> match. If the
>>>> feedpoint in the shack has 1000 ohms of inductive
>>>> reactance, and the
>>>> tuner has only 600 ohms capacitive reactance to
>> attempt to
>>>> cancel that
>>>> inductance, then a match will never happen.
>
>
>
> ______________________________________________________________
> 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
>