Re: [Elecraft] KAT500 tuning behavior when the load is impossible to match ?

[Wes Stewart]

It's easier with a tuner that has lossy components. It's really easy with a tee 
tuner with three adjustable components.  There are many matching solutions, only 
one of them is the lowest loss.


On 4/2/2017 2:12 PM, Don Wilhelm wrote:

Phil,

It is indeed possible to match a very high SWR or even an open circuit or a 
short.

That will be more probable on the higher frequency bands than on the lower 
bands.

73,
Don W3FPR 


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Re: [Elecraft] KAT500 tuning behavior when the load is impossible to match ?

[Ron D'Eau Claire]

To answer your other question, if the KAT500 cannot find a match better than
1.5:1 the FAULT indicator on the front panel will light. You will also
trigger a fault if:

1) The RF power is above 110 watts while tuning to protect the relays from
arcing. 

2) The impedance can be matched but is outside of the KAT500's normal tuning
range with an impedance that may produce RF voltages that could damage the
components considering the RF power applied. In that case, the fault occurs
when you raise the RF power. However, it is safe to operate at any power
level below which the fault occurs.

73, Ron AC7AC 



-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Don
Wilhelm
Sent: Sunday, April 2, 2017 2:12 PM
To: Phil Hystad; Elecraft Reflector
Subject: Re: [Elecraft] KAT500 tuning behavior when the load is impossible
to match ?

Phil,

It is indeed possible to match a very high SWR or even an open circuit or a
short.
That will be more probable on the higher frequency bands than on the lower
bands.

73,
Don W3FPR
On 4/2/2017 12:42 PM, Phil Hystad wrote:
> I got my second KAT500 tuner to use with my new backup rig and while
setting up and testing and tuning with my two different antennas I made a
mistake.
>
> I first observed the results displayed on the utility program operate page
where the tuned SWR was 1:1 and the bypass SWR was something like 54:1.  I
immediately realized that something was not right and discovered that my
coax cable was not switched to the antenna but rather my dummy load but the
cable to the dummy load was disconnected (because I was moving things
around).
>
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Re: [Elecraft] KAT500 tuning behavior when the load is impossible to match ?

[Don Wilhelm]

Phil,

It is indeed possible to match a very high SWR or even an open circuit 
or a short.
That will be more probable on the higher frequency bands than on the 
lower bands.


73,
Don W3FPR
On 4/2/2017 12:42 PM, Phil Hystad wrote:

I got my second KAT500 tuner to use with my new backup rig and while setting up 
and testing and tuning with my two different antennas I made a mistake.

I first observed the results displayed on the utility program operate page 
where the tuned SWR was 1:1 and the bypass SWR was something like 54:1.  I 
immediately realized that something was not right and discovered that my coax 
cable was not switched to the antenna but rather my dummy load but the cable to 
the dummy load was disconnected (because I was moving things around).


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Re: [Elecraft] KAT500 tuning behavior when the load is impossible to match ?

[Phil Hystad]

Your story reminds me of a scene from that Godzilla movie with Matthew 
Broderick where he is “pumping” over sized worms from the ground using 
electricity.

73, phil, K7PEH


> On Apr 2, 2017, at 10:05 AM, Mike Rhodes  wrote:
> 
> No practical experience with the KAT500 but can tell you that, years ago, 
> while guest operation at a contest station, a 160 meter vertical was strung 
> up between a couple of the towers. The operator went in and successfully 
> tuned the antenna to a 1:1 match and then loaded the KW amp to full output. 
> He then went S to get warmed up but heard very little and could not work 
> any of the few stations he did hear. We went out and discovered that the 
> vertical wire had snagged on the ground rod! The tuner was manual but imagine 
> the same principal applies. Yes, you can often get a "perfect" match but that 
> may not count for much! Have often wondered if the earth worm population in 
> that area ever recovered.
> 
> Mike / W8DN
> 
> On 4/2/2017 12:42 PM, Phil Hystad wrote:
>> I got my second KAT500 tuner to use with my new backup rig and while setting 
>> up and testing and tuning with my two different antennas I made a mistake.
>> 
>> I first observed the results displayed on the utility program operate page 
>> where the tuned SWR was 1:1 and the bypass SWR was something like 54:1.  I 
>> immediately realized that something was not right and discovered that my 
>> coax cable was not switched to the antenna but rather my dummy load but the 
>> cable to the dummy load was disconnected (because I was moving things 
>> around).
>> 
>> OK, fixed that little problem but I was curious about the behavior when the 
>> KAT500 tuner is faced with an impossible match. Does it give up?  I assume 
>> it gives up but then I didn’t see anything to indicate that the tuning 
>> operation gave up.  In fact, it seemed like it found a tuned LC solution but 
>> one that was matched with a bypass of 54:1.
>> 
>> My first question:  If KAT500 fails to find a valid solution does it report 
>> an error.  I ask this because at times I have had red LED lights flashing on 
>> a failed tune but I did not have one this time.  I am wondering if I missed 
>> the error report on the utility program.
>> 
>> My second question:  Is it possible that the KAT500 did resolve a tuned LC 
>> solution with basically 6 feet of coaxial cable unconnected with anything?
>> 
>> Thanks,
>> 
>> 73, phil, K7PEH
>> 
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Re: [Elecraft] KAT500 tuning behavior when the load is impossible to match ?

[Mike Rhodes]

No practical experience with the KAT500 but can tell you that, years 
ago, while guest operation at a contest station, a 160 meter vertical 
was strung up between a couple of the towers. The operator went in and 
successfully tuned the antenna to a 1:1 match and then loaded the KW amp 
to full output. He then went S to get warmed up but heard very little 
and could not work any of the few stations he did hear. We went out and 
discovered that the vertical wire had snagged on the ground rod! The 
tuner was manual but imagine the same principal applies. Yes, you can 
often get a "perfect" match but that may not count for much! Have often 
wondered if the earth worm population in that area ever recovered.


Mike / W8DN

On 4/2/2017 12:42 PM, Phil Hystad wrote:

I got my second KAT500 tuner to use with my new backup rig and while setting up 
and testing and tuning with my two different antennas I made a mistake.

I first observed the results displayed on the utility program operate page 
where the tuned SWR was 1:1 and the bypass SWR was something like 54:1.  I 
immediately realized that something was not right and discovered that my coax 
cable was not switched to the antenna but rather my dummy load but the cable to 
the dummy load was disconnected (because I was moving things around).

OK, fixed that little problem but I was curious about the behavior when the 
KAT500 tuner is faced with an impossible match. Does it give up?  I assume it 
gives up but then I didn’t see anything to indicate that the tuning operation 
gave up.  In fact, it seemed like it found a tuned LC solution but one that was 
matched with a bypass of 54:1.

My first question:  If KAT500 fails to find a valid solution does it report an 
error.  I ask this because at times I have had red LED lights flashing on a 
failed tune but I did not have one this time.  I am wondering if I missed the 
error report on the utility program.

My second question:  Is it possible that the KAT500 did resolve a tuned LC 
solution with basically 6 feet of coaxial cable unconnected with anything?

Thanks,

73, phil, K7PEH

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