Re: [Elecraft] KAT500 and KAT500 Utility Question

[Wes (N7WS)]

I don't believe that it has anything to do with whether or not a match can be 
reached.  Some SWRs are simply too difficult to measure accurately, even with an 
error-corrected network analyzer.  For near ideal reactances or very high or 
very low SWR, reflection measurements are inappropriate.  In other words, if the 
impedance is on or near the periphery of a Smith Chart (rho ~ 1) find another 
method.


On 11/4/2015 1:59 PM, Phil Hystad wrote:

[snip]

So, I am assuming that unless the KAT500 reaches a tuned SWR value under 1.5:1 
(or, whatever threshold I set), the BYPASS SWR is totally meaningless.

73, phil, K7PEH




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Re: [Elecraft] KAT500 and KAT500 Utility Question

[Wes (N7WS)]

Some of what you say is true, but has nothing to do with the problem.

Soapbox comment: Personally, I would (and do) rather use Heliax before I would 
ever use ladder line.



On 11/4/2015 2:21 PM, Ken wrote:
The results almost totally depend on the length of the ladder line. At certain 
lengths, it will act as an impedance transformer and could load your 80m 
dipole quite well.  An 80m dipole on 160 will have a low impedance at the feed 
point.   A quarter wave of ladder line will transform that impedance to a 
higher impedance. A half wave of ladder line will give the same impedance (no 
transformer effect.)


If you have something near a half wave of ladder line, the 4:1 balun is 
totally wrong since it will transform a low impedance to one 4x lower!


Try it with a 1: balun and see if the SWR improves or not.

As for actual, honest SWR readings, I assume that most meters are unreliable 
in the actual readings when the SWR gets high, especially 10:1 and above.   
They are really built to operate in the 50 ohm range, not 500 or 1000.


BTW, IMO the KAT500 is one of the best tuners I've used and I've been building 
or using them for over 50 years.


Ken WA8JXM



On 11/4/15 3:59 PM, Phil Hystad wrote:
First, this is a curiosity question about KAT500 utility only.  I don’t 
intend to use my antenna on 160 meters.


I use the KAT500 with my 80-meter dipole fed by ladder line and a 4:1 Balun 
to Coax for last 20 feet.  This antenna works excellently in concert with the 
KAT500 for 80, 40, and 30 meter bands.  I don’t use it with other bands.


This weekend, I was curious as to how close (or far) the KAT500 could bring 
the antenna in for the 160 meter band.  I knew that it would not work though 
I was wondering how bad it would be.


So, as I expected, the tuning never closed in on a descent SWR, the best I 
saw on one test only was SWR about 49:1 as reported by the KAT500 utility.  
But, the BYPASS SWR reported was about 11:1.


Further tests showed varying bad reports of incomplete tuned SWR while also 
showing a much lower BYPASS SWR (under 13:1). According to my own tests of 
the impedance for the antenna on 160 meters, the BYPASS SWR is bogus.


So, I am assuming that unless the KAT500 reaches a tuned SWR value under 
1.5:1 (or, whatever threshold I set), the BYPASS SWR is totally meaningless.


73, phil, K7PEH




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Re: [Elecraft] KAT500 and KAT500 Utility Question

[Ken]

The results almost totally depend on the length of the ladder line.   At 
certain lengths, it will act as an impedance transformer and could load 
your 80m dipole quite well.  An 80m dipole on 160 will have a low 
impedance at the feed point.   A quarter wave of ladder line will 
transform that impedance to a higher impedance. A half wave of ladder 
line will give the same impedance (no transformer effect.)


If you have something near a half wave of ladder line, the 4:1 balun is 
totally wrong since it will transform a low impedance to one 4x lower!


Try it with a 1: balun and see if the SWR improves or not.

As for actual, honest SWR readings, I assume that most meters are 
unreliable in the actual readings when the SWR gets high, especially 
10:1 and above.   They are really built to operate in the 50 ohm range, 
not 500 or 1000.


BTW, IMO the KAT500 is one of the best tuners I've used and I've been 
building or using them for over 50 years.


Ken WA8JXM



On 11/4/15 3:59 PM, Phil Hystad wrote:

First, this is a curiosity question about KAT500 utility only.  I don’t intend 
to use my antenna on 160 meters.

I use the KAT500 with my 80-meter dipole fed by ladder line and a 4:1 Balun to 
Coax for last 20 feet.  This antenna works excellently in concert with the 
KAT500 for 80, 40, and 30 meter bands.  I don’t use it with other bands.

This weekend, I was curious as to how close (or far) the KAT500 could bring the 
antenna in for the 160 meter band.  I knew that it would not work though I was 
wondering how bad it would be.

So, as I expected, the tuning never closed in on a descent SWR, the best I saw 
on one test only was SWR about 49:1 as reported by the KAT500 utility.  But, 
the BYPASS SWR reported was about 11:1.

Further tests showed varying bad reports of incomplete tuned SWR while also 
showing a much lower BYPASS SWR (under 13:1).  According to my own tests of the 
impedance for the antenna on 160 meters, the BYPASS SWR is bogus.

So, I am assuming that unless the KAT500 reaches a tuned SWR value under 1.5:1 
(or, whatever threshold I set), the BYPASS SWR is totally meaningless.

73, phil, K7PEH




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[Elecraft] KAT500 and KAT500 Utility Question

[Phil Hystad]

First, this is a curiosity question about KAT500 utility only.  I don’t intend 
to use my antenna on 160 meters.

I use the KAT500 with my 80-meter dipole fed by ladder line and a 4:1 Balun to 
Coax for last 20 feet.  This antenna works excellently in concert with the 
KAT500 for 80, 40, and 30 meter bands.  I don’t use it with other bands.

This weekend, I was curious as to how close (or far) the KAT500 could bring the 
antenna in for the 160 meter band.  I knew that it would not work though I was 
wondering how bad it would be.

So, as I expected, the tuning never closed in on a descent SWR, the best I saw 
on one test only was SWR about 49:1 as reported by the KAT500 utility.  But, 
the BYPASS SWR reported was about 11:1.

Further tests showed varying bad reports of incomplete tuned SWR while also 
showing a much lower BYPASS SWR (under 13:1).  According to my own tests of the 
impedance for the antenna on 160 meters, the BYPASS SWR is bogus.

So, I am assuming that unless the KAT500 reaches a tuned SWR value under 1.5:1 
(or, whatever threshold I set), the BYPASS SWR is totally meaningless.

73, phil, K7PEH


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Re: [Elecraft] KAT500 and KAT500 Utility Question

[Fred Jensen]

On 11/4/2015 12:59 PM, Phil Hystad wrote:


I use the KAT500 with my 80-meter dipole fed by ladder line and a 4:1
Balun to Coax for last 20 feet.  This antenna works excellently in
concert with the KAT500 for 80, 40, and 30 meter bands.  I don’t use
it with other bands.


Feed point Z's:
1.9: 5.6-j1149
3.9: 78+j2
7.2: 2703+j2201

Your ladder line will transform these impedances to something else ... 
unless it happens to be a multiple of a half-wave at one of those 
frequencies.  Tell me how long it is and we can calculate what it looks 
like on the high side of your 4:1 transformer.  I don't recommend 
holding your breath that it will be good on all three bands though.


This weekend, I was curious as to how close (or far) the KAT500 could
bring the antenna in for the 160 meter band.  I knew that it would
not work though I was wondering how bad it would be.


The radiation resistance on 160 will be very low and the 4:1 transformer 
will divide it by 4, meaning just a tad above 1 ohm.  It is also very 
reactive.


If you really want to use it on 160, try shorting the ladder line at the 
feed end, remove the transformer, and connect the shorted end to the 
coax through a variable cap.  Run 1 or 2 wires on the ground from the 
coax shield and see if you can feed it as a Marconi-T.


If your ladder line is 60 ft long, feed Z at the shorted end of the 
ladder line will be about 110+j1400 and an Xc of 1400 ohms will probably 
work fine for the KAT500.


So, as I expected, the tuning never closed in on a descent SWR, the
best I saw on one test only was SWR about 49:1 as reported by the
KAT500 utility.  But, the BYPASS SWR reported was about 11:1.


SWR meters, which usually measure VSWR are fairly unreliable at high 
values of mismatch.


73,

Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org

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Re: [Elecraft] KAT500 and KAT500 Utility Question

[Wes (N7WS)]

Guys, read what he wrote, not what you think he wrote.

He had a question about the operation of the metering in the KAT500, he wasn't 
looking for advice on antenna design or on the use of ladder line.


If he wants that he can read my paper here: 
http://k6mhe.com/n7ws/Ladder_Line.pdf


11/4/2015 3:37 PM, Fred Jensen wrote:

On 11/4/2015 12:59 PM, Phil Hystad wrote:


I use the KAT500 with my 80-meter dipole fed by ladder line and a 4:1
Balun to Coax for last 20 feet.  This antenna works excellently in
concert with the KAT500 for 80, 40, and 30 meter bands.  I don’t use
it with other bands.


Feed point Z's:
1.9: 5.6-j1149
3.9: 78+j2
7.2: 2703+j2201

Your ladder line will transform these impedances to something else ... unless 
it happens to be a multiple of a half-wave at one of those frequencies.  Tell 
me how long it is and we can calculate what it looks like on the high side of 
your 4:1 transformer.  I don't recommend holding your breath that it will be 
good on all three bands though.


This weekend, I was curious as to how close (or far) the KAT500 could
bring the antenna in for the 160 meter band.  I knew that it would
not work though I was wondering how bad it would be.


The radiation resistance on 160 will be very low and the 4:1 transformer will 
divide it by 4, meaning just a tad above 1 ohm. It is also very reactive.


If you really want to use it on 160, try shorting the ladder line at the feed 
end, remove the transformer, and connect the shorted end to the coax through a 
variable cap.  Run 1 or 2 wires on the ground from the coax shield and see if 
you can feed it as a Marconi-T.


If your ladder line is 60 ft long, feed Z at the shorted end of the ladder 
line will be about 110+j1400 and an Xc of 1400 ohms will probably work fine 
for the KAT500.


So, as I expected, the tuning never closed in on a descent SWR, the
best I saw on one test only was SWR about 49:1 as reported by the
KAT500 utility.  But, the BYPASS SWR reported was about 11:1.


SWR meters, which usually measure VSWR are fairly unreliable at high values of 
mismatch.


73,

Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org

Message delivered to w...@triconet.org


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Re: [Elecraft] KAT500 and KAT500 Utility Question

[Jim Brown]

On Wed,11/4/2015 3:04 PM, Wes (N7WS) wrote:
If he wants that he can read my paper here: 
http://k6mhe.com/n7ws/Ladder_Line.pdf


By all means DO read and STUDY it -- it's a GREAT piece of work.

73, Jim K9YC
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Re: [Elecraft] KAT500 and KAT500 Utility Question

[Phil Hystad]

Wes…

Thanks, you are exactly right.  My curiosity is about what the KAT500 was doing 
and the value of the BYPASS SWR versus the values I saw of the Tuned (or, not 
tuned) SWR.  

Dick’s answer was right on and satisfied all my curiosity needs.

Though thanks to all that took the time to write something down and Wes, I will 
read your paper at your link.  In fact, just downloaded it.

73, phil, K7PEH



> On Nov 4, 2015, at 3:04 PM, Wes (N7WS)  wrote:
> 
> Guys, read what he wrote, not what you think he wrote.
> 
> He had a question about the operation of the metering in the KAT500, he 
> wasn't looking for advice on antenna design or on the use of ladder line.
> 
> If he wants that he can read my paper here: 
> http://k6mhe.com/n7ws/Ladder_Line.pdf
> 
> 
> 11/4/2015 3:37 PM, Fred Jensen wrote:
>> On 11/4/2015 12:59 PM, Phil Hystad wrote:
>> 
>>> I use the KAT500 with my 80-meter dipole fed by ladder line and a 4:1
>>> Balun to Coax for last 20 feet.  This antenna works excellently in
>>> concert with the KAT500 for 80, 40, and 30 meter bands.  I don’t use
>>> it with other bands.
>> 
>> Feed point Z's:
>>1.9: 5.6-j1149
>>3.9: 78+j2
>>7.2: 2703+j2201
>> 
>> Your ladder line will transform these impedances to something else ... 
>> unless it happens to be a multiple of a half-wave at one of those 
>> frequencies.  Tell me how long it is and we can calculate what it looks like 
>> on the high side of your 4:1 transformer.  I don't recommend holding your 
>> breath that it will be good on all three bands though.
>>> 
>>> This weekend, I was curious as to how close (or far) the KAT500 could
>>> bring the antenna in for the 160 meter band.  I knew that it would
>>> not work though I was wondering how bad it would be.
>> 
>> The radiation resistance on 160 will be very low and the 4:1 transformer 
>> will divide it by 4, meaning just a tad above 1 ohm. It is also very 
>> reactive.
>> 
>> If you really want to use it on 160, try shorting the ladder line at the 
>> feed end, remove the transformer, and connect the shorted end to the coax 
>> through a variable cap.  Run 1 or 2 wires on the ground from the coax shield 
>> and see if you can feed it as a Marconi-T.
>> 
>> If your ladder line is 60 ft long, feed Z at the shorted end of the ladder 
>> line will be about 110+j1400 and an Xc of 1400 ohms will probably work fine 
>> for the KAT500.
>>> 
>>> So, as I expected, the tuning never closed in on a descent SWR, the
>>> best I saw on one test only was SWR about 49:1 as reported by the
>>> KAT500 utility.  But, the BYPASS SWR reported was about 11:1.
>> 
>> SWR meters, which usually measure VSWR are fairly unreliable at high values 
>> of mismatch.
>> 
>> 73,
>> 
>> Fred K6DGW
>> - Northern California Contest Club
>> - CU in the Cal QSO Party 1-2 Oct 2016
>> - www.cqp.org
>> 
>> Message delivered to w...@triconet.org
> 
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