KPA500 Faulting on high SWR on power rise

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KPA500 Faulting on high SWR on power rise

Chris Hallinan
Greetings from southwest Florida.

My KPA500 is kicking out with REFL HI warning (high SWR).  But here is the
strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner -> 4:1
balun -> open wire feedline to 80-meter doublet.  In words, I have a remote
autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
Balun Designs 4:1 balun provides the interface from the open wire line to
the tuner.

With the autotuner tuned at low power, the SWR shows 1.5:1 on my KPA500 and
external SWR meter.  As I run the power up to 300, 400, 500 watts,
somewhere in there all of a sudden the SWR instantly jumps off the scale,
into the red LEDs on KPA500, and it faults.  It's as if the SWR were
dependent on power.

Even stranger, when I back the power off to say 250 Watts, holding key down
the SWR is stable in the green (<1.5:1), but when I key it at CW rates, the
SWR bounces into the red on every dit and eventually faults, when at steady
state key down it never leaves the green zone!

I fear it is the tuner falling over, but it should be able to handle the
power.  I see this on all bands from 80-20.

Operating into my 20-meter resonant vertical, with no tuner, everything
works fine.

Any ideas or hints on how to correct this?

Thanks,

Chris
73 de K1AY


--
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Re: KPA500 Faulting on high SWR on power rise

Gary K9GS
Hi Chris,
Unless there is something arcing, I would guess RF getting into something.  Maybe the control cable to the auto tuner?  


73,
Gary K9GS
-------- Original message --------From: Chris Hallinan <[hidden email]> Date: 2/23/18  11:42 PM  (GMT-06:00) To: "<[hidden email]>" <[hidden email]> Subject: [Elecraft] KPA500 Faulting on high SWR on power rise
Greetings from southwest Florida.

My KPA500 is kicking out with REFL HI warning (high SWR).  But here is the
strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner -> 4:1
balun -> open wire feedline to 80-meter doublet.  In words, I have a remote
autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
Balun Designs 4:1 balun provides the interface from the open wire line to
the tuner.

With the autotuner tuned at low power, the SWR shows 1.5:1 on my KPA500 and
external SWR meter.  As I run the power up to 300, 400, 500 watts,
somewhere in there all of a sudden the SWR instantly jumps off the scale,
into the red LEDs on KPA500, and it faults.  It's as if the SWR were
dependent on power.

Even stranger, when I back the power off to say 250 Watts, holding key down
the SWR is stable in the green (<1.5:1), but when I key it at CW rates, the
SWR bounces into the red on every dit and eventually faults, when at steady
state key down it never leaves the green zone!

I fear it is the tuner falling over, but it should be able to handle the
power.  I see this on all bands from 80-20.

Operating into my 20-meter resonant vertical, with no tuner, everything
works fine.

Any ideas or hints on how to correct this?

Thanks,

Chris
73 de K1AY


--
Life is like Linux - it never stands still.
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Re: KPA500 Faulting on high SWR on power rise

Rick WA6NHC-2
In reply to this post by Chris Hallinan
It appears that the higher voltages at QRO are enough on return to fault the amp.  That could be an arc or the match isn’t really 1:1.   Using an antenna analyzer at the balun would be useful.

If you’re on 80M, without the tuner, you’re likely to see ~3:1 untuned at the balun, within the range that should almost work, BUT it also depends on the length of the open wire feed.  (Using a 75 ohm feed would be wiser if used for only 80M).

Try modeling it on EZ-NEC, then adjust the feed (in the model) by some feet to see what that does.  If you’re using it for multiband, you’ll have to run it for each band.  Getting it to work well on all bands is a serious challenge, near impossible; something has to give.

It’s likely too that the model won’t show coupling or losses exactly to the real world (metal, trees, walls), so if it suggests you make changes, you’ll still have to adjust to your real antenna.  In short, go play.

My 340’ 80M EDZ was textbook perfect (2 opposing 5/8 wave, center fed, NOT resonant) but didn’t load that way, until I added almost 30’ more antenna AND shortened the feed by 50’ in the real world.  After more than 200 countries later (on all bands 160-10), I’d say it worked pretty well.   Not easy, but I was patient.  Having a K3 made the difference, often the DX did too.

Good luck, it’s one of the fun things to do in ham radio.

73,
Rick WA6NHC

Smell Czech correction happen

> On Feb 23, 2018, at 9:42 PM, Chris Hallinan <[hidden email]> wrote:
>
> Greetings from southwest Florida.
>
> My KPA500 is kicking out with REFL HI warning (high SWR).  But here is the
> strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner -> 4:1
> balun -> open wire feedline to 80-meter doublet.  In words, I have a remote
> autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
> Balun Designs 4:1 balun provides the interface from the open wire line to
> the tuner.
>
> With the autotuner tuned at low power, the SWR shows 1.5:1 on my KPA500 and
> external SWR meter.  As I run the power up to 300, 400, 500 watts,
> somewhere in there all of a sudden the SWR instantly jumps off the scale,
> into the red LEDs on KPA500, and it faults.  It's as if the SWR were
> dependent on power.
>
> Even stranger, when I back the power off to say 250 Watts, holding key down
> the SWR is stable in the green (<1.5:1), but when I key it at CW rates, the
> SWR bounces into the red on every dit and eventually faults, when at steady
> state key down it never leaves the green zone!
>
> I fear it is the tuner falling over, but it should be able to handle the
> power.  I see this on all bands from 80-20.
>
> Operating into my 20-meter resonant vertical, with no tuner, everything
> works fine.
>
> Any ideas or hints on how to correct this?
>
> Thanks,
>
> Chris
> 73 de K1AY
>
>
> --
> Life is like Linux - it never stands still.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
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Re: KPA500 Faulting on high SWR on power rise

Logan Zintsmaster
In reply to this post by Chris Hallinan

I’d guess that something is going on in the tuner. Maybe a leaky gasket and some corrosion.

Logan
Sent from my iPhone

> On Feb 23, 2018, at 10:00 PM, GaryK9GS <[hidden email]> wrote:
>
> Hi Chris,
> Unless there is something arcing, I would guess RF getting into something.  Maybe the control cable to the auto tuner?  
>
>
> 73,
> Gary K9GS
> -------- Original message --------From: Chris Hallinan <[hidden email]> Date: 2/23/18  11:42 PM  (GMT-06:00) To: "<[hidden email]>" <[hidden email]> Subject: [Elecraft] KPA500 Faulting on high SWR on power rise
> Greetings from southwest Florida.
>
> My KPA500 is kicking out with REFL HI warning (high SWR).  But here is the
> strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner -> 4:1
> balun -> open wire feedline to 80-meter doublet.  In words, I have a remote
> autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
> Balun Designs 4:1 balun provides the interface from the open wire line to
> the tuner.
>
> With the autotuner tuned at low power, the SWR shows 1.5:1 on my KPA500 and
> external SWR meter.  As I run the power up to 300, 400, 500 watts,
> somewhere in there all of a sudden the SWR instantly jumps off the scale,
> into the red LEDs on KPA500, and it faults.  It's as if the SWR were
> dependent on power.
>
> Even stranger, when I back the power off to say 250 Watts, holding key down
> the SWR is stable in the green (<1.5:1), but when I key it at CW rates, the
> SWR bounces into the red on every dit and eventually faults, when at steady
> state key down it never leaves the green zone!
>
> I fear it is the tuner falling over, but it should be able to handle the
> power.  I see this on all bands from 80-20.
>
> Operating into my 20-meter resonant vertical, with no tuner, everything
> works fine.
>
> Any ideas or hints on how to correct this?
>
> Thanks,
>
> Chris
> 73 de K1AY
>
>
> --
> Life is like Linux - it never stands still.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
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Re: KPA500 Faulting on high SWR on power rise

Jack Brindle-2
In reply to this post by Chris Hallinan
Others have mentioned arcing as a possibility. We see more of than than we would like. There are many poor UHF connectors and (especially) adapters around. This is especially true with right angle connectors.

There is another possibility that could be happening. RF loves any wire it can find for return currents. The outer braid of the 40 feet of coax could be doing a great job of picking up RF and conducting it back to the KPA500. We usually see this with vertical antennas which are very happy to use the feedline for return current, but this also could be happening with your setup. The idea is that at HF, current flows on the edge of the braid. In this case there are two edges, one inside the cable (closest to the center conductor, with the second on the other (outer) side. The current you expect is flowing on the inside, and the outer can pick up anything stray, including the signal you are trying to radiate. This is conducted back to the amplifier where it really messes up the sample signal. I would also expect you to see RFI with this setup.

A third possibility comes from where you now live. As I learned long ago as a young ham in Miami, the South Florida heat is very harmful to coax cable. Over (an amazingly short) time the coax inner conductor can migrate through the insulation and come into contact with the shield. This is very common, occurs within just a few years (or months in some cases) and requires coax to be replaced every few years. It almost always occurs at bends in the coax. This, of course, leads directly to the arcing issue described above (and by others). Foam dielectric coax is probably the worst with this issue. The solution is new coax. And do your best not to bend the cable!

The solution to the second issue is a good balun choke. K9YC would advise running the coax through a large toroid several times to help resolve the problem. An alternate is to use a large number of coax-size toroids fed onto the coax, which will also choke off the unwanted currents. You might want to prefer the latter because of the same migration issue described above. In this case the turns on the toroid _will_ fail within a short time.

See K9YC’s excellent web page for more information. He has a very good paper on baluns, especially choke baluns.

Best o flick solving this issue. That South Florida sun and heat can play havoc with ham stations. Much different problems than those seen in 1-land!

73,

Jack, W6FB, ex-WA4FIB


> On Feb 23, 2018, at 9:42 PM, Chris Hallinan <[hidden email]> wrote:
>
> Greetings from southwest Florida.
>
> My KPA500 is kicking out with REFL HI warning (high SWR).  But here is the
> strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner -> 4:1
> balun -> open wire feedline to 80-meter doublet.  In words, I have a remote
> autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
> Balun Designs 4:1 balun provides the interface from the open wire line to
> the tuner.
>
> With the autotuner tuned at low power, the SWR shows 1.5:1 on my KPA500 and
> external SWR meter.  As I run the power up to 300, 400, 500 watts,
> somewhere in there all of a sudden the SWR instantly jumps off the scale,
> into the red LEDs on KPA500, and it faults.  It's as if the SWR were
> dependent on power.
>
> Even stranger, when I back the power off to say 250 Watts, holding key down
> the SWR is stable in the green (<1.5:1), but when I key it at CW rates, the
> SWR bounces into the red on every dit and eventually faults, when at steady
> state key down it never leaves the green zone!
>
> I fear it is the tuner falling over, but it should be able to handle the
> power.  I see this on all bands from 80-20.
>
> Operating into my 20-meter resonant vertical, with no tuner, everything
> works fine.
>
> Any ideas or hints on how to correct this?
>
> Thanks,
>
> Chris
> 73 de K1AY
>
>
> --
> Life is like Linux - it never stands still.
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

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Re: KPA500 Faulting on high SWR on power rise

Victor Rosenthal 4X6GP
In reply to this post by Chris Hallinan
Just to add to all the possibilities, there could be an arc at the
balun. Most authorities suggest a 1:1 balun with a setup like this. As
you know, the impedance seen at the balun will vary all over the map,
depending on the band and the length of the 600-ohm line.

I've calculated that the voltage that appears at that point in my
somewhat similar setup is as high as 7 kV when I'm running 1200 watts on
one particular band. A 1:1 balun designed for tuner use (e.g., one like
this:
<https://www.dxengineering.com/parts/dxe-bal050h10at> or this:
<https://www.dxengineering.com/parts/dxe-bal050h11ct>
would be suitable.

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/
On 24 Feb 2018 07:42, Chris Hallinan wrote:

> Greetings from southwest Florida.
>
> My KPA500 is kicking out with REFL HI warning (high SWR).  But here is the
> strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner -> 4:1
> balun -> open wire feedline to 80-meter doublet.  In words, I have a remote
> autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
> Balun Designs 4:1 balun provides the interface from the open wire line to
> the tuner.
>
> With the autotuner tuned at low power, the SWR shows 1.5:1 on my KPA500 and
> external SWR meter.  As I run the power up to 300, 400, 500 watts,
> somewhere in there all of a sudden the SWR instantly jumps off the scale,
> into the red LEDs on KPA500, and it faults.  It's as if the SWR were
> dependent on power.
>
> Even stranger, when I back the power off to say 250 Watts, holding key down
> the SWR is stable in the green (<1.5:1), but when I key it at CW rates, the
> SWR bounces into the red on every dit and eventually faults, when at steady
> state key down it never leaves the green zone!
>
> I fear it is the tuner falling over, but it should be able to handle the
> power.  I see this on all bands from 80-20.
>
> Operating into my 20-meter resonant vertical, with no tuner, everything
> works fine.
>
> Any ideas or hints on how to correct this?
>
> Thanks,
>
> Chris
> 73 de K1AY
>
>
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Re: KPA500 Faulting on high SWR on power rise

Chris Hallinan
Thanks, everyone for the helpful hints.  Some additional information:
This installation is brand new.  The antenna has been up only a month or
so.  Tuner and Balun even less.  Coax is newly run, and I've deliberately
avoided sharp bends.  I purchased the KPA500 in December, so all of this
QRO is new for me (in this century at least!)
I am running through a surge protectors from Alpha Delta.  I will double
check is is not the 200W versions!  Hmmm, now that I think of it, maybe
that's it???   Will check after coffee!

Any tips on how I would detect/locate any potential arcing?

I do understand the nature of the antenna and the potential wide range of
impedances possible with this multi-band setup.
-
I'm going to scan it at the balun this morning with my AIM 4300 for
starters.  Oh, and check/bypass the surge protector too!

Thanks again,

73 de K1AY
Chris

On Sat, Feb 24, 2018 at 7:44 AM, Victor Rosenthal 4X6GP <[hidden email]
> wrote:

> Just to add to all the possibilities, there could be an arc at the balun.
> Most authorities suggest a 1:1 balun with a setup like this. As you know,
> the impedance seen at the balun will vary all over the map, depending on
> the band and the length of the 600-ohm line.
>
> I've calculated that the voltage that appears at that point in my somewhat
> similar setup is as high as 7 kV when I'm running 1200 watts on one
> particular band. A 1:1 balun designed for tuner use (e.g., one like this:
> <https://www.dxengineering.com/parts/dxe-bal050h10at> or this:
> <https://www.dxengineering.com/parts/dxe-bal050h11ct>
> would be suitable.
>
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> Formerly K2VCO
> http://www.qsl.net/k2vco/
>
> On 24 Feb 2018 07:42, Chris Hallinan wrote:
>
>> Greetings from southwest Florida.
>>
>> My KPA500 is kicking out with REFL HI warning (high SWR).  But here is the
>> strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner ->
>> 4:1
>> balun -> open wire feedline to 80-meter doublet.  In words, I have a
>> remote
>> autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
>> Balun Designs 4:1 balun provides the interface from the open wire line to
>> the tuner.
>>
>> With the autotuner tuned at low power, the SWR shows 1.5:1 on my KPA500
>> and
>> external SWR meter.  As I run the power up to 300, 400, 500 watts,
>> somewhere in there all of a sudden the SWR instantly jumps off the scale,
>> into the red LEDs on KPA500, and it faults.  It's as if the SWR were
>> dependent on power.
>>
>> Even stranger, when I back the power off to say 250 Watts, holding key
>> down
>> the SWR is stable in the green (<1.5:1), but when I key it at CW rates,
>> the
>> SWR bounces into the red on every dit and eventually faults, when at
>> steady
>> state key down it never leaves the green zone!
>>
>> I fear it is the tuner falling over, but it should be able to handle the
>> power.  I see this on all bands from 80-20.
>>
>> Operating into my 20-meter resonant vertical, with no tuner, everything
>> works fine.
>>
>> Any ideas or hints on how to correct this?
>>
>> Thanks,
>>
>> Chris
>> 73 de K1AY
>>
>>
>>


--
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Re: KPA500 Faulting on high SWR on power rise

Don Wilhelm
In reply to this post by Chris Hallinan
Chris,

You have seen several posts with good advice.  If you want to do an easy
test to localize where the failure may be, you can do it with a dummy load.
First put the dummy load at the rig.  Check to see if all is OK, if not,
blame the rig.
Then check the coax - connect the dummy load at the end of your coax
(replacing the remote tuner).  If the problem shows up, then blame the coax.

If all is still OK with the dummy load at the end of the coax, you can
blame the tuner, balun or the antenna or RF getting onto the coax outer
shield.  Look for evidence of arcing, make sure all connections are
solid - then try adding a K9YC type current mode choke near the entry
point entry to the shack to choke RF coming in on the outside of the
coax braid.

73,
Don W3FPR


On 2/24/2018 12:42 AM, Chris Hallinan wrote:

> Greetings from southwest Florida.
>
> My KPA500 is kicking out with REFL HI warning (high SWR).  But here is the
> strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner -> 4:1
> balun -> open wire feedline to 80-meter doublet.  In words, I have a remote
> autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
> Balun Designs 4:1 balun provides the interface from the open wire line to
> the tuner.
>
> With the autotuner tuned at low power, the SWR shows 1.5:1 on my KPA500 and
> external SWR meter.  As I run the power up to 300, 400, 500 watts,
> somewhere in there all of a sudden the SWR instantly jumps off the scale,
> into the red LEDs on KPA500, and it faults.  It's as if the SWR were
> dependent on power.
>
> Even stranger, when I back the power off to say 250 Watts, holding key down
> the SWR is stable in the green (<1.5:1), but when I key it at CW rates, the
> SWR bounces into the red on every dit and eventually faults, when at steady
> state key down it never leaves the green zone!
>
> I fear it is the tuner falling over, but it should be able to handle the
> power.  I see this on all bands from 80-20.
>
> Operating into my 20-meter resonant vertical, with no tuner, everything
> works fine.
>
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Re: KPA500 Faulting on high SWR on power rise

Carl Yaffey
In reply to this post by Jack Brindle-2
Another possibility: There is a spurious signal on a widely different frequency. I experienced this.

Carl Yaffey  K8NU
Recording studio.
[hidden email]
614 268 6353, Columbus OH
http://www.carl-yaffey.com
http://www.grassahol.com
http://www.bluesswing.com

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Re: KPA500 Faulting on high SWR on power rise

NK7Z
In reply to this post by Don Wilhelm
Triage the problem...

Dummy load at the end of the tuner chain-- if it works at high power
then all is good from the dummy load back, the problem lies downstream
of the dummy load.  If it fails with the dummy load there, then you have
a coax problem between the radio and the dummy load.

So far you have done a bit of triaging already, if you operate on the
vertical, with no tuner, and all is good, then you know the radio and
amp are OK.  You also know the feed line to whatever type of coax switch
you have is OK...

Move the dummy load around to triage out as much as possible...

If you don't have a dummy load, you need one...  Every station needs a
dummy load just for this sort of testing.

73s and thanks,
Dave
NK7Z
https://www.nk7z.net


> On 2/24/2018 12:42 AM, Chris Hallinan wrote:
>> Greetings from southwest Florida.
>>
>> My KPA500 is kicking out with REFL HI warning (high SWR).  But here is
>> the
>> strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner
>> -> 4:1
>> balun -> open wire feedline to 80-meter doublet.  In words, I have a
>> remote
>> autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
>> Balun Designs 4:1 balun provides the interface from the open wire line to
>> the tuner.
>>
>> With the autotuner tuned at low power, the SWR shows 1.5:1 on my
>> KPA500 and
>> external SWR meter.  As I run the power up to 300, 400, 500 watts,
>> somewhere in there all of a sudden the SWR instantly jumps off the scale,
>> into the red LEDs on KPA500, and it faults.  It's as if the SWR were
>> dependent on power.
>>
>> Even stranger, when I back the power off to say 250 Watts, holding key
>> down
>> the SWR is stable in the green (<1.5:1), but when I key it at CW
>> rates, the
>> SWR bounces into the red on every dit and eventually faults, when at
>> steady
>> state key down it never leaves the green zone!
>>
>> I fear it is the tuner falling over, but it should be able to handle the
>> power.  I see this on all bands from 80-20.
>>
>> Operating into my 20-meter resonant vertical, with no tuner, everything
>> works fine.
>>
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Re: KPA500 Faulting on high SWR on power rise

Carl Yaffey
I mentioned a spurious signal. I tested this by using a different rig. No problem with it. Sent the K3S for repair.

Carl Yaffey  K8NU
Recording studio.
[hidden email]
614 268 6353, Columbus OH
http://www.carl-yaffey.com
http://www.grassahol.com
http://www.bluesswing.com

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Re: KPA500 Faulting on high SWR on power rise

Arthur Nienhouse
In reply to this post by Don Wilhelm
*/Chris/*
> You have seen several posts with good advice.  If you want to do an
> easy test to localize where the failure may be, you can do it with a
> dummy load.
> First put the dummy load at the rig.  Check to see if all is OK, if
> not, blame the rig.
> Then check the coax - connect the dummy load at the end of your coax
> (replacing the remote tuner).
*/Good advice all,  I was running brand new Belden RG213U coax to a
diamond dual band antenna did the connectors both ends, did the pull 75'
saw the same situation .......hum can't be the coax it brand new off the
reel must be my connector installation.....replaced both (Amphenol
connectors again) what it was was a fault in the *brand new coax* I
found the fault cut it out made up a couple of shorter runs from the
original piece I cut for the radio to antenna run. /*
> If the problem shows up, then blame the coax.
*/Yep don't rule out anything ............/*
>
>
> If all is still OK with the dummy load at the end of the coax, you can
> blame the tuner, balun or the antenna or RF getting onto the coax
> outer shield.  Look for evidence of arcing, make sure all connections
> are solid - then try adding a K9YC type current mode choke near the
> entry point entry to the shack to choke RF coming in on the outside of
> the coax braid.
*/Regards
Art
ka9zap
/*

>
>
>
>
> On 2/24/2018 12:42 AM, Chris Hallinan wrote:
>> Greetings from southwest Florida.
>>
>> My KPA500 is kicking out with REFL HI warning (high SWR).  But here
>> is the
>> strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner
>> -> 4:1
>> balun -> open wire feedline to 80-meter doublet.  In words, I have a
>> remote
>> autotuner feeding an 80-meter doublet fed with 600-ohm open wire
>> line.  A
>> Balun Designs 4:1 balun provides the interface from the open wire
>> line to
>> the tuner.
>>
>> With the autotuner tuned at low power, the SWR shows 1.5:1 on my
>> KPA500 and
>> external SWR meter.  As I run the power up to 300, 400, 500 watts,
>> somewhere in there all of a sudden the SWR instantly jumps off the
>> scale,
>> into the red LEDs on KPA500, and it faults.  It's as if the SWR were
>> dependent on power.
>>
>> Even stranger, when I back the power off to say 250 Watts, holding
>> key down
>> the SWR is stable in the green (<1.5:1), but when I key it at CW
>> rates, the
>> SWR bounces into the red on every dit and eventually faults, when at
>> steady
>> state key down it never leaves the green zone!
>>
>> I fear it is the tuner falling over, but it should be able to handle the
>> power.  I see this on all bands from 80-20.
>>
>> Operating into my 20-meter resonant vertical, with no tuner, everything
>> works fine.
>>
> ______________________________________________________________
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Re: KPA500 Faulting on high SWR on power rise

Wes Stewart-2
In reply to this post by Chris Hallinan
Regardless, I would get rid of those. Pity I can't post pictures here of my
examination of the two I bought and returned.

Wes  N7WS


On 2/24/2018 6:36 AM, Chris Hallinan wrote:
> ...
> I am running through a surge protectors from Alpha Delta.  I will double
> check is is not the 200W versions!  Hmmm, now that I think of it, maybe
> that's it???   ...
>
> 73 de K1AY
> Chris
>

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Re: KPA500 Faulting on high SWR on power rise

Chris Hallinan
In reply to this post by Don Wilhelm
Thanks Don, and everyone.
This morning, after reading the posts, I took an approach similar to what
Don is proposing.
I bypassed the surge protector, and voila, problem gone.
Now I have a new problem:  The Alpha Delta model TT3G50 is clearly marked
HP, but it's behaving like a 200W version.
The good news - that's an easier problem to solve.  Sometimes just being
able to discuss the issue helps one solve it.

Thanks everyone for all the help and support.

73 de K1AY
Chris

On Sat, Feb 24, 2018 at 8:44 AM, Don Wilhelm <[hidden email]> wrote:

> Chris,
>
> You have seen several posts with good advice.  If you want to do an easy
> test to localize where the failure may be, you can do it with a dummy load.
> First put the dummy load at the rig.  Check to see if all is OK, if not,
> blame the rig.
> Then check the coax - connect the dummy load at the end of your coax
> (replacing the remote tuner).  If the problem shows up, then blame the coax.
>
> If all is still OK with the dummy load at the end of the coax, you can
> blame the tuner, balun or the antenna or RF getting onto the coax outer
> shield.  Look for evidence of arcing, make sure all connections are solid -
> then try adding a K9YC type current mode choke near the entry point entry
> to the shack to choke RF coming in on the outside of the coax braid.
>
> 73,
> Don W3FPR
>
>
>
> On 2/24/2018 12:42 AM, Chris Hallinan wrote:
>
>> Greetings from southwest Florida.
>>
>> My KPA500 is kicking out with REFL HI warning (high SWR).  But here is the
>> strangeness. My setup is K3->KPA500->40' coax->MFJ 600W remote tuner ->
>> 4:1
>> balun -> open wire feedline to 80-meter doublet.  In words, I have a
>> remote
>> autotuner feeding an 80-meter doublet fed with 600-ohm open wire line.  A
>> Balun Designs 4:1 balun provides the interface from the open wire line to
>> the tuner.
>>
>> With the autotuner tuned at low power, the SWR shows 1.5:1 on my KPA500
>> and
>> external SWR meter.  As I run the power up to 300, 400, 500 watts,
>> somewhere in there all of a sudden the SWR instantly jumps off the scale,
>> into the red LEDs on KPA500, and it faults.  It's as if the SWR were
>> dependent on power.
>>
>> Even stranger, when I back the power off to say 250 Watts, holding key
>> down
>> the SWR is stable in the green (<1.5:1), but when I key it at CW rates,
>> the
>> SWR bounces into the red on every dit and eventually faults, when at
>> steady
>> state key down it never leaves the green zone!
>>
>> I fear it is the tuner falling over, but it should be able to handle the
>> power.  I see this on all bands from 80-20.
>>
>> Operating into my 20-meter resonant vertical, with no tuner, everything
>> works fine.
>>
>>


--
Life is like Linux - it never stands still.
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Re: KPA500 Faulting on high SWR on power rise

Chris Hallinan
In reply to this post by Wes Stewart-2
Hi Wes. Appreciate the feedback.  I'm certainly not impressed by having one
marked HP that is clearly not.  See my earlier post: the surge protector
was my problem all along.  It's arcing at about 300W.

Do you have a suggestion for alternatives?  I live in the lightning capital
of the world ;)  Lightning mitigation is not optional here.

Chris K1AY

On Sat, Feb 24, 2018 at 9:39 AM, Wes Stewart <[hidden email]> wrote:

> Regardless, I would get rid of those. Pity I can't post pictures here of
> my examination of the two I bought and returned.
>
> Wes  N7WS
>
>
> On 2/24/2018 6:36 AM, Chris Hallinan wrote:
>
>> ...
>> I am running through a surge protectors from Alpha Delta.  I will double
>> check is is not the 200W versions!  Hmmm, now that I think of it, maybe
>> that's it???   ...
>>
>> 73 de K1AY
>> Chris
>>
>>
> ______________________________________________________________
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>
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> Message delivered to [hidden email]
>



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Re: KPA500 Faulting on high SWR on power rise

ke9uw
Are the Alpha surge protectors different than the arc plugs in the Delta-4 switches? I've never had an issue with those at high power.
Are they designed to operate at a low impedance (50 ohms) which would present a much lower voltage peak?
Or could the arc plug in them become damaged and cause them to arc at a much lower voltage?

Chuck Hawley
 [hidden email]

 Amateur Radio, KE9UW
 aka Jack, BMW Motorcycles
________________________________________
From: [hidden email] [[hidden email]] on behalf of Chris Hallinan [[hidden email]]
Sent: Saturday, February 24, 2018 9:32 AM
To: Wes Stewart
Cc: <[hidden email]>
Subject: Re: [Elecraft] KPA500 Faulting on high SWR on power rise

Hi Wes. Appreciate the feedback.  I'm certainly not impressed by having one
marked HP that is clearly not.  See my earlier post: the surge protector
was my problem all along.  It's arcing at about 300W.

Do you have a suggestion for alternatives?  I live in the lightning capital
of the world ;)  Lightning mitigation is not optional here.

Chris K1AY

On Sat, Feb 24, 2018 at 9:39 AM, Wes Stewart <[hidden email]> wrote:

> Regardless, I would get rid of those. Pity I can't post pictures here of
> my examination of the two I bought and returned.
>
> Wes  N7WS
>
>
> On 2/24/2018 6:36 AM, Chris Hallinan wrote:
>
>> ...
>> I am running through a surge protectors from Alpha Delta.  I will double
>> check is is not the 200W versions!  Hmmm, now that I think of it, maybe
>> that's it???   ...
>>
>> 73 de K1AY
>> Chris
>>
>>
> ______________________________________________________________
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
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Re: KPA500 Faulting on high SWR on power rise

Don Wilhelm
In reply to this post by Chris Hallinan
Chris,

What is the possibility that you have an HP suppressor body and a 200
watt Arc-Plug?

73,
Don W3FPR

On 2/24/2018 10:32 AM, Chris Hallinan wrote:
> Hi Wes. Appreciate the feedback.  I'm certainly not impressed by having one
> marked HP that is clearly not.  See my earlier post: the surge protector
> was my problem all along.  It's arcing at about 300W.
>
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Re: KPA500 Faulting on high SWR on power rise

Chris Hallinan
Not sure.  I pulled the plug out and Googled the numbers on it.  The plug
is labeled CG2 1000, which I think means it is a 1000V breakdown voltage.
It appears to be a Littlefuse device, according to Allied Electronics which
has the leaded version of the part for $2 ;)

Without knowing for sure, 1000V seems plenty for a 500W amp into
approximately 50 ohms load.  Note I have the surge protector on the low SWR
side of the tuner which is mounted under an eve of the house.  Probably not
ideal but that's another issue ;)

Chris



On Sat, Feb 24, 2018 at 11:06 AM, Don Wilhelm <[hidden email]>
wrote:

> Chris,
>
> What is the possibility that you have an HP suppressor body and a 200 watt
> Arc-Plug?
>
> 73,
> Don W3FPR
>
>
> On 2/24/2018 10:32 AM, Chris Hallinan wrote:
>
>> Hi Wes. Appreciate the feedback.  I'm certainly not impressed by having
>> one
>> marked HP that is clearly not.  See my earlier post: the surge protector
>> was my problem all along.  It's arcing at about 300W.
>>
>>


--
Life is like Linux - it never stands still.
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Re: KPA500 Faulting on high SWR on power rise

Richard Stutsman
In reply to this post by Chris Hallinan
MFJ tuners that use switched tapped air inductors often fail to allow
sufficient spacing between each tap and the adjacent turns of the coil, and
either heat expansion or high-voltage arcing can cause shorts between the
tap and an adjacent turn, completely changing the effective tuner settings,
as a result. On MFJ's "Mobile" tuner I had to bend the adjacent turns away
from the soldered taps (by pushing each adjacent quarter turn into the
coil's interior, which is standard practice for these air inductors) in
order to get it to work right.

Rick N6IET
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Re: KPA500 Faulting on high SWR on power rise

Bill K9YEQ
In reply to this post by Chris Hallinan
1000v to me could be too low for a 500W amp.  You can for the time being leave the plug out, just disconnect when you are not using your equipment.  I use a remote disconnect to remove the antennas at my remote grounding panel.

73,
Bill
K9YEQ

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Chris Hallinan
Sent: Saturday, February 24, 2018 10:51 AM
To: [hidden email]
Cc: Wes Stewart <[hidden email]>; <[hidden email]> <[hidden email]>
Subject: Re: [Elecraft] KPA500 Faulting on high SWR on power rise

Not sure.  I pulled the plug out and Googled the numbers on it.  The plug is labeled CG2 1000, which I think means it is a 1000V breakdown voltage.
It appears to be a Littlefuse device, according to Allied Electronics which has the leaded version of the part for $2 ;)

Without knowing for sure, 1000V seems plenty for a 500W amp into approximately 50 ohms load.  Note I have the surge protector on the low SWR side of the tuner which is mounted under an eve of the house.  Probably not ideal but that's another issue ;)

Chris



On Sat, Feb 24, 2018 at 11:06 AM, Don Wilhelm <[hidden email]>
wrote:

> Chris,
>
> What is the possibility that you have an HP suppressor body and a 200
> watt Arc-Plug?
>
> 73,
> Don W3FPR
>
>
> On 2/24/2018 10:32 AM, Chris Hallinan wrote:
>
>> Hi Wes. Appreciate the feedback.  I'm certainly not impressed by
>> having one marked HP that is clearly not.  See my earlier post: the
>> surge protector was my problem all along.  It's arcing at about 300W.
>>
>>


--
Life is like Linux - it never stands still.
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12