Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[Tom N4LSJ]

I had something similar happen, and it was the capacitor in the EFHW 
heating up on 12 and 10 meters.  It didn't  heat up on any other bands.



On 7/17/22 11:38, Andy Durbin wrote:

Don't need to have ferrite in the antenna system to see this sort of SWR 
"runaway".   I have the same problem with my home brew small transmitting loop 
if I run over 100 W.

Spent some time trying to figure out what was heating and causing the loop's 
resonant frequency to shift. My preliminary analysis showed expected 
temperature coefficient was opposite sign to that observed.   Decided the only 
way to really understand the problem was thermal imaging but have not got round 
to that yet.

Andy, k3wyc
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Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[CUTTER DAVID via Elecraft]

Hello Andy

The main reason I abandoned small transmitting loops was their susceptibility 
to temperature variation, one cause being power input, the other due to 
instantaneous change when the sun comes out.  

Apologies for sliding off topic. 

David G3UNA
  
> On 17/07/2022 16:38 Andy Durbin  wrote:
> 
>  
> Don't need to have ferrite in the antenna system to see this sort of SWR 
> "runaway".   I have the same problem with my home brew small transmitting 
> loop if I run over 100 W.
> Andy, k3wyc
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[Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[Andy Durbin]

Don't need to have ferrite in the antenna system to see this sort of SWR 
"runaway".   I have the same problem with my home brew small transmitting loop 
if I run over 100 W.

Spent some time trying to figure out what was heating and causing the loop's 
resonant frequency to shift. My preliminary analysis showed expected 
temperature coefficient was opposite sign to that observed.   Decided the only 
way to really understand the problem was thermal imaging but have not got round 
to that yet.

Andy, k3wyc
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Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[Bill Johnson]

From what has been stated, this not a true end fed Half wave using a 9-1 balun. 
 That is the issue.  The balun needs to be a 49-1 ratio to properly feed an 
EFHW antenna.  The method you are using requires a different counterpoise than 
an EFHW.  EFHW are efficient at one frequency and direct harmonics.  So, the 
balun is likely heating up.  The 53' antenna is a random wire and needs to have 
a proper counterpoise.  Random end feds are  different birds.

Bill
K9YEQ

-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of David Gilbert
Sent: Friday, July 15, 2022 10:42 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my 
KPA500


No.  Over time the current does not "back up".

Something in your system is heating up.  My bet would be that your toroids used 
as common mode chokes are heating up due to the very high voltages that exist 
at the end of an end fed half wave antenna.  It's not likely to be a current 
problem since there isn't much current at all at the end of a half wave antenna 
... unless yours isn't actually a half wave at whatever frequency your feeding 
it.

It is also possible that something in the Palstar tuner is heating up, but it 
uses decent looking inductors wound on ceramic forms so I really doubt it.

I'm guessing that you aren't using any sort of counterpoise with your EFHW.  If 
you did, it would have the effect of making your EFHW look a bit more like just 
a severely off-center fed dipole with the result that the voltage (and possibly 
the mismatch) would be less.

In any case, don't go key down any longer than you need to if you don't want to 
fry the toroids before you get a chance to fix the problem.

73,
Dave AB7E



On 7/15/2022 7:53 PM, Peder Kittelson wrote:
> When on 80 meters, the longer I hold the tune button down the higher 
> the SWR goes to the point the KPA500 folds back with warnings.  I 
> don't usually hold down the tune button longer than about 5-6 seconds.
>
> I use a Manual Palstar BT1500A tuner which does a good job of tuning 
> my EFHW wire antenna.  So the initial tune is very good. I sometimes 
> will hold down the Tune button on the K3s for maybe 5-6 seconds with 
> the initial tune at 1-1 SWR.
>
> The KP500 first shows a 1-1 SWR.  Then 1.2-1, 1.3-1 and so on.  I stop 
> when it reaches 1.5-1.
>
> I suppose that initially the transmitting wire sends out the signal 
> and over time the current backs up.  I have torroids in place to 
> prevent RFI coming back down the antenna transmission line.
>
> I only use the system for CW.  So when I send, the problem does not 
> escalate to the point of a dangerous SWR.
>
> I wonder if this is a normal problem when holding the tuning button 
> longer?  And since I do not hold down the key for a long period of 
> time it doesn't develop.
>
> Still, I am looking at solutions. And I am concerned.
>
> Your thoughts?
>

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Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[David Gilbert]

No.  Over time the current does not "back up".

Something in your system is heating up.  My bet would be that your 
toroids used as common mode chokes are heating up due to the very high 
voltages that exist at the end of an end fed half wave antenna.  It's 
not likely to be a current problem since there isn't much current at all 
at the end of a half wave antenna ... unless yours isn't actually a half 
wave at whatever frequency your feeding it.


It is also possible that something in the Palstar tuner is heating up, 
but it uses decent looking inductors wound on ceramic forms so I really 
doubt it.


I'm guessing that you aren't using any sort of counterpoise with your 
EFHW.  If you did, it would have the effect of making your EFHW look a 
bit more like just a severely off-center fed dipole with the result that 
the voltage (and possibly the mismatch) would be less.


In any case, don't go key down any longer than you need to if you don't 
want to fry the toroids before you get a chance to fix the problem.


73,
Dave AB7E



On 7/15/2022 7:53 PM, Peder Kittelson wrote:

When on 80 meters, the longer I hold the tune button down the higher the
SWR goes to the point the KPA500 folds back with warnings.  I don't usually
hold down the tune button longer than about 5-6 seconds.

I use a Manual Palstar BT1500A tuner which does a good job of tuning my
EFHW wire antenna.  So the initial tune is very good. I sometimes will hold
down the Tune button on the K3s for maybe 5-6 seconds with the initial tune
at 1-1 SWR.

The KP500 first shows a 1-1 SWR.  Then 1.2-1, 1.3-1 and so on.  I stop when
it reaches 1.5-1.

I suppose that initially the transmitting wire sends out the signal and
over time the current backs up.  I have torroids in place to prevent RFI
coming back down the antenna transmission line.

I only use the system for CW.  So when I send, the problem does not
escalate to the point of a dangerous SWR.

I wonder if this is a normal problem when holding the tuning button
longer?  And since I do not hold down the key for a long period of time it
doesn't develop.

Still, I am looking at solutions. And I am concerned.

Your thoughts?



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Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[Dave Erickson]

On 7/15/2022 10:35 PM, Peder Kittelson wrote:
That is a good question.  I was thinking of adding to the answer above.  
I called Palstar about a year ago and asked if there was any problem 
linking a coax cable through a short length of balanced line.  He said 
he did not see any problem with that.  So I have used the tuner that way 
and until now have not had any problem with it that I have noticed.  It 
is unusual to be sure.


Thanks again for your help,

Peder

On Fri, Jul 15, 2022 at 8:28 PM Dave Erickson > wrote:


On 7/15/2022 10:21 PM, Peder Kittelson wrote:
 > The antenna is homemade, in a sense.  I bought a 9-1 Balun from
Balun
 > Designs with the capacity for a tie into a counterpoise which I
use.  I
 > have a 30 DB inline RF attenuator attached to the Balun Designs
piece.
 > I have run RG213 to my radio room.  I have a separate Palomar 9-1
Un-Un
 > in the line near my equipment.  The EFHW transmission wire is 53
feet
 > long.  A length recommended for multiband EFHW wires.  That
length has
 > no natural resonance which would cause problems, according to the
charts
 > I have seen.
 >
 > Thank you for your thoughts
 >
 > Peder
 >
 > On Fri, Jul 15, 2022 at 8:07 PM Dave Erickson
mailto:ra...@disseminator.net>
 > >>
wrote:
 >
 >     On 7/15/2022 9:53 PM, Peder Kittelson wrote:
 >      > When on 80 meters, the longer I hold the tune button down the
 >     higher the
 >      > SWR goes to the point the KPA500 folds back with warnings.  I
 >     don't usually
 >      > hold down the tune button longer than about 5-6 seconds.
 >      >
 >      > I use a Manual Palstar BT1500A tuner which does a good job of
 >     tuning my
 >      > EFHW wire antenna.  So the initial tune is very good. I
sometimes
 >     will hold
 >      > down the Tune button on the K3s for maybe 5-6 seconds with the
 >     initial tune
 >      > at 1-1 SWR.
 >      >
 >      > The KP500 first shows a 1-1 SWR.  Then 1.2-1, 1.3-1 and so
on.  I
 >     stop when
 >      > it reaches 1.5-1.
 >      >
 >      > I suppose that initially the transmitting wire sends out the
 >     signal and
 >      > over time the current backs up.  I have torroids in place to
 >     prevent RFI
 >      > coming back down the antenna transmission line.
 >      >
 >      > I only use the system for CW.  So when I send, the problem
does not
 >      > escalate to the point of a dangerous SWR.
 >      >
 >      > I wonder if this is a normal problem when holding the
tuning button
 >      > longer?  And since I do not hold down the key for a long
period
 >     of time it
 >      > doesn't develop.
 >      >
 >      > Still, I am looking at solutions. And I am concerned.
 >      >
 >      > Your thoughts?
 >      >
 >
 >     Hi,
 >
 >     Are you feeding an EFHW antenna with balanced feed-line? I don't
 >     believe
 >     I have seen that done much.
 >
 >     Is your antenna commercial or home made? I'd like to see more
about
 >     that.

Peder,

I am a little confused I guess, but how does this antenna system work
with the Palstar BT1500A which only has connections for balanced
feed-line?

There is a lot going on there I think.


Peder,

That is a fairly unique arrangement to be sure.

Good Luck, I hope you find the answer.

--
Dave Erickson
AB0R
73

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Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[Dave Erickson]

On 7/15/2022 10:21 PM, Peder Kittelson wrote:
The antenna is homemade, in a sense.  I bought a 9-1 Balun from Balun 
Designs with the capacity for a tie into a counterpoise which I use.  I 
have a 30 DB inline RF attenuator attached to the Balun Designs piece.  
I have run RG213 to my radio room.  I have a separate Palomar 9-1 Un-Un 
in the line near my equipment.  The EFHW transmission wire is 53 feet 
long.  A length recommended for multiband EFHW wires.  That length has 
no natural resonance which would cause problems, according to the charts 
I have seen.


Thank you for your thoughts

Peder

On Fri, Jul 15, 2022 at 8:07 PM Dave Erickson > wrote:


On 7/15/2022 9:53 PM, Peder Kittelson wrote:
 > When on 80 meters, the longer I hold the tune button down the
higher the
 > SWR goes to the point the KPA500 folds back with warnings.  I
don't usually
 > hold down the tune button longer than about 5-6 seconds.
 >
 > I use a Manual Palstar BT1500A tuner which does a good job of
tuning my
 > EFHW wire antenna.  So the initial tune is very good. I sometimes
will hold
 > down the Tune button on the K3s for maybe 5-6 seconds with the
initial tune
 > at 1-1 SWR.
 >
 > The KP500 first shows a 1-1 SWR.  Then 1.2-1, 1.3-1 and so on.  I
stop when
 > it reaches 1.5-1.
 >
 > I suppose that initially the transmitting wire sends out the
signal and
 > over time the current backs up.  I have torroids in place to
prevent RFI
 > coming back down the antenna transmission line.
 >
 > I only use the system for CW.  So when I send, the problem does not
 > escalate to the point of a dangerous SWR.
 >
 > I wonder if this is a normal problem when holding the tuning button
 > longer?  And since I do not hold down the key for a long period
of time it
 > doesn't develop.
 >
 > Still, I am looking at solutions. And I am concerned.
 >
 > Your thoughts?
 >

Hi,

Are you feeding an EFHW antenna with balanced feed-line? I don't
believe
I have seen that done much.

Is your antenna commercial or home made? I'd like to see more about
that.


Peder,

I am a little confused I guess, but how does this antenna system work 
with the Palstar BT1500A which only has connections for balanced feed-line?


There is a lot going on there I think.

--
Dave Erickson
AB0R
73

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Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[Victor Rosenthal 4X6GP]

Something in the antenna system is heating up. Ferrite 
baluns/transformers are likely culprits.


73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
On 16-Jul-2022 05:53, Peder Kittelson wrote:

When on 80 meters, the longer I hold the tune button down the higher the
SWR goes to the point the KPA500 folds back with warnings.  I don't usually
hold down the tune button longer than about 5-6 seconds.

I use a Manual Palstar BT1500A tuner which does a good job of tuning my
EFHW wire antenna.  So the initial tune is very good. I sometimes will hold
down the Tune button on the K3s for maybe 5-6 seconds with the initial tune
at 1-1 SWR.

The KP500 first shows a 1-1 SWR.  Then 1.2-1, 1.3-1 and so on.  I stop when
it reaches 1.5-1.

I suppose that initially the transmitting wire sends out the signal and
over time the current backs up.  I have torroids in place to prevent RFI
coming back down the antenna transmission line.

I only use the system for CW.  So when I send, the problem does not
escalate to the point of a dangerous SWR.

I wonder if this is a normal problem when holding the tuning button
longer?  And since I do not hold down the key for a long period of time it
doesn't develop.

Still, I am looking at solutions. And I am concerned.

Your thoughts?


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Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[Dave Erickson]

On 7/15/2022 9:53 PM, Peder Kittelson wrote:

When on 80 meters, the longer I hold the tune button down the higher the
SWR goes to the point the KPA500 folds back with warnings.  I don't usually
hold down the tune button longer than about 5-6 seconds.

I use a Manual Palstar BT1500A tuner which does a good job of tuning my
EFHW wire antenna.  So the initial tune is very good. I sometimes will hold
down the Tune button on the K3s for maybe 5-6 seconds with the initial tune
at 1-1 SWR.

The KP500 first shows a 1-1 SWR.  Then 1.2-1, 1.3-1 and so on.  I stop when
it reaches 1.5-1.

I suppose that initially the transmitting wire sends out the signal and
over time the current backs up.  I have torroids in place to prevent RFI
coming back down the antenna transmission line.

I only use the system for CW.  So when I send, the problem does not
escalate to the point of a dangerous SWR.

I wonder if this is a normal problem when holding the tuning button
longer?  And since I do not hold down the key for a long period of time it
doesn't develop.

Still, I am looking at solutions. And I am concerned.

Your thoughts?




Hi,

Are you feeding an EFHW antenna with balanced feed-line? I don't believe 
I have seen that done much.


Is your antenna commercial or home made? I'd like to see more about that.


--
Dave Erickson
AB0R
73

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Re: [Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[Dave (NK7Z)]

Hi,
A bit more information please...

1.  How much power are you putting out?

2.  How long in seconds before the SWR starts to increase?

3.  What is the native antenna SWR, not what the tuner is showing, but 
the real SWR?


4.  Are you running with a balun of any kind?

5.  What type of antenna?

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 7/15/22 19:53, Peder Kittelson wrote:

When on 80 meters, the longer I hold the tune button down the higher the
SWR goes to the point the KPA500 folds back with warnings.  I don't usually
hold down the tune button longer than about 5-6 seconds.

I use a Manual Palstar BT1500A tuner which does a good job of tuning my
EFHW wire antenna.  So the initial tune is very good. I sometimes will hold
down the Tune button on the K3s for maybe 5-6 seconds with the initial tune
at 1-1 SWR.

The KP500 first shows a 1-1 SWR.  Then 1.2-1, 1.3-1 and so on.  I stop when
it reaches 1.5-1.

I suppose that initially the transmitting wire sends out the signal and
over time the current backs up.  I have torroids in place to prevent RFI
coming back down the antenna transmission line.

I only use the system for CW.  So when I send, the problem does not
escalate to the point of a dangerous SWR.

I wonder if this is a normal problem when holding the tuning button
longer?  And since I do not hold down the key for a long period of time it
doesn't develop.

Still, I am looking at solutions. And I am concerned.

Your thoughts?


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[Elecraft] Using the K3s Tune button causes a growing SWR on my KPA500

[Peder Kittelson]

When on 80 meters, the longer I hold the tune button down the higher the
SWR goes to the point the KPA500 folds back with warnings.  I don't usually
hold down the tune button longer than about 5-6 seconds.

I use a Manual Palstar BT1500A tuner which does a good job of tuning my
EFHW wire antenna.  So the initial tune is very good. I sometimes will hold
down the Tune button on the K3s for maybe 5-6 seconds with the initial tune
at 1-1 SWR.

The KP500 first shows a 1-1 SWR.  Then 1.2-1, 1.3-1 and so on.  I stop when
it reaches 1.5-1.

I suppose that initially the transmitting wire sends out the signal and
over time the current backs up.  I have torroids in place to prevent RFI
coming back down the antenna transmission line.

I only use the system for CW.  So when I send, the problem does not
escalate to the point of a dangerous SWR.

I wonder if this is a normal problem when holding the tuning button
longer?  And since I do not hold down the key for a long period of time it
doesn't develop.

Still, I am looking at solutions. And I am concerned.

Your thoughts?

-- 
Peder Kittelson, W7RPK
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