Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Don Wilhelm]

While all the "facts" about the voltage ratings of the gas discharge 
protectors are correct - that is only true if those devices are new and 
have not 'squashed' a number of events.


Please consider that this ham's problem with the Alpha-Delta protector 
may be simply that the gas-discharge device in the protector has 
absorbed enough energy (both from lightning and from RF) that its rating 
is no longer the same as a new one.


Those devices do degrade after a number of "events"-
That is the reason why Alpha-Delta gas discharge devices are replaceable 
- they do not last forever.  Some other protection devices do not have 
parts that are as easily replaceable, and you have to replace the entire 
protector.


73,
Don W3FPR

On 2/25/2018 6:42 PM, j...@kk9a.com wrote:

Your 5KW example is RMS voltage and peak would be 707v. I am not sure how
much moderate SWR effect this value but clearly the 1000v Alpha Delta
discharge tube should be adequate for an Elecraft KPA-500 unless the SWR is
horrible.

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[Elecraft] KPA500 Faulting on high SWR on power rise

[john]

Your 5KW example is RMS voltage and peak would be 707v. I am not sure how
much moderate SWR effect this value but clearly the 1000v Alpha Delta
discharge tube should be adequate for an Elecraft KPA-500 unless the SWR is
horrible.

John KK9A


From: K4TAX
Date: Sat Feb 24 19:46:55 EST 2018

Based on the specification of 500 volts peak,5KW at 50 ohms = 500 
volts.  It would seem the PL-259 is adequate for ham radio applications 
per specification to 0.3 GHZ or 300 MHz without issues. Of course 
one is dealing with 50 ohms, which implies essentially a 1:1 SWR.

73

Bob, K4TAX

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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Don Wilhelm]

Rick and all,

Whether that is true or not depends on the length of the radiator and 
feedline relative to the frequency.  Read my "Antennas" article on my 
website www.w3fpr.com.


There is good reason that the Elecraft BL2 is switchable between 1:1 and 
4:1.


73,
Don W3FPR

On 2/24/2018 10:53 PM, Rick Bates (WA6NHC) wrote:

In my case, the 4:1 was shown as correct by comparing to a 1:1 (for me).  I was 
able to find more usable bands with the 4:1 (meaning closer matches).

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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Mark Goldberg]

There are a lot of factors that determine what the best choice of Balun is.
Unless it is a resonant antenna, the impedance is not purely resistive,
usually far from it. It can be almost anything. The feedline length will
affect what the impedance is at the tuner. The tuner, if you have one, will
select, or you will select the configuration and values of inductance and
capacitance that provide the correct match. Those components, especially
the inductors have losses and heat up. You don't generally know what those
losses are and they vary from part to part.

The tuner It can often match with a 1:1, 4:1 and other baluns, as long as
the impedance seen by the tuner is within it's range. The claims that a
tuner can tune 10:1 or 3:1 are not that useful, except for a general
comparison. They can't match every possible impedance, inductive,
capacitive or whatever within that range. Depending on the manufacturer's
choices of values, they may be able to match a higher SWR if it is very
inductive, rather than capacitive, for example. The optimal match will also
be determined by the losses. You may be able to get a match, but 50% of
your power may be absorbed by the tuner, with smoke eventually being let
out.

I use a homebrewed dual core switchable 4:1 / 1:1 currrent balun. Most of
the time, the tuner can match my Horizontal loop with the switch in either
position. It may result in a lower SWR in one position or the other and I
usually choose the position that results in the lowest SWR after the tuner
matches. In a few cases, after transmitting for a while, the tuner will try
to retune. I believe that is likely due to an inductor heating up in the
tuner and changing value. That tells me the losses are likely high and I
try the other switch position and see if it stays tuned. If you know what
impedance your antenna system and feedline present to the tuner, you may be
able to choose an optimal balun. In my case, with so many bands, there is
no single best choice. I choose whatever works best on that particular
frequency.

73,

Mark
W7MLG

On Sat, Feb 24, 2018 at 8:30 PM, Bob McGraw K4TAX 
wrote:

> I question the 4:1 balun being the correct nor best choice. Typical of
> that antenna the feed Z of the radiator is more likely 25 to 35 ohms. The
> 4:1 balun is presenting something like 10 ohms to the tuner. Worst case for
> high current and hi loss in the tuner causing heating.   A 1:1 balun would
> seem more likely correct.
>
> Many seem to "think" a 4:1 balun is correct when using open wire or a
> balanced line to "match the line".
>
> Bob, K4TAX
>
>
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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Rick Bates (WA6NHC)]

In my case, the 4:1 was shown as correct by comparing to a 1:1 (for me).  I was 
able to find more usable bands with the 4:1 (meaning closer matches). 

If the dipole is single band only, using a 75 ohm feed (choke at the transition 
from feed to antenna) is best.   A resonant dipole is closer to 72 ohms, 
ignoring local conditions, one of which is elevation above ground.   Inverted 
vee systems are lower impedance so 50 ohm is the proper choice (again, single 
band only).

For this example of multiband use AND open wire feed (for dramatically lower 
feed loss at high SWR) which alters the impedance of the system and the length 
of the feed matters; one can use an analyzer to find which transformer works 
best or simply try both. 

The 4:1 presents a bit more device loss compared to a 1:1, but if it also 
provides near resonance on more bands, so that loss is negligible. 

With open line (75-600 ohm typical) you don’t match the line with the balun, 
you match what the SYSTEM presents, antenna and feed. 

Rick WA6NHC

Smell Czech correction happen

> On Feb 24, 2018, at 7:30 PM, Bob McGraw K4TAX  wrote:
> 
> I question the 4:1 balun being the correct nor best choice. Typical of that 
> antenna the feed Z of the radiator is more likely 25 to 35 ohms. The 4:1 
> balun is presenting something like 10 ohms to the tuner. Worst case for high 
> current and hi loss in the tuner causing heating.   A 1:1 balun would seem 
> more likely correct. 
> 
> Many seem to "think" a 4:1 balun is correct when using open wire or a 
> balanced line to "match the line". 
> 
> Bob, K4TAX
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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Bob McGraw K4TAX]

Yes and in years past AM legal limit PEP power was about 3KW.  PL-259's were 
used on these transmitters and Johnson KW Matchbox type equipment. 

Bob, K4TAX


Sent from my iPhone

> On Feb 24, 2018, at 8:59 PM, Jim Brown  wrote:
> 
> Someone should tell the electrons. UHF connectors have been standard on legal 
> limit power amps for as long as I've been a ham.
> 
> 73, Jim K9YC
> 
>> On 2/24/2018 1:46 PM, Walter Underwood wrote:
>> The Amphenol voltage rating for UHF connectors is 500 V peak. So the 
>> connectors could be another weak point.
>> 
>> https://www.amphenolrf.com/connectors/uhf.html
> 
> 
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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Bob McGraw K4TAX]

I question the 4:1 balun being the correct nor best choice. Typical of that 
antenna the feed Z of the radiator is more likely 25 to 35 ohms. The 4:1 balun 
is presenting something like 10 ohms to the tuner. Worst case for high current 
and hi loss in the tuner causing heating.   A 1:1 balun would seem more likely 
correct. 

Many seem to "think" a 4:1 balun is correct when using open wire or a balanced 
line to "match the line". 

Bob, K4TAX


Sent from my iPhone

> On Feb 24, 2018, at 8:59 PM, Jim Brown  wrote:
> 
> Someone should tell the electrons. UHF connectors have been standard on legal 
> limit power amps for as long as I've been a ham.
> 
> 73, Jim K9YC
> 
>> On 2/24/2018 1:46 PM, Walter Underwood wrote:
>> The Amphenol voltage rating for UHF connectors is 500 V peak. So the 
>> connectors could be another weak point.
>> 
>> https://www.amphenolrf.com/connectors/uhf.html
> 
> 
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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Jim Brown]

Someone should tell the electrons. UHF connectors have been standard on 
legal limit power amps for as long as I've been a ham.


73, Jim K9YC

On 2/24/2018 1:46 PM, Walter Underwood wrote:

The Amphenol voltage rating for UHF connectors is 500 V peak. So the connectors 
could be another weak point.

https://www.amphenolrf.com/connectors/uhf.html



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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Bob McGraw K4TAX]

I've observed many times an arc occur from the center pin to shell with 
an unterminated line during a thunder storm.   No damage to the 
connector occurred however.   Makes for an eerie dang sound too.


73

Bob K4TAX



On 2/24/2018 8:29 PM, GaryK9GS wrote:

I have never seen a properly installed UHF connector, in a matched system, arc.


73,
Gary K9GS
 Original message From: j...@kk9a.com Date: 2/24/18  5:14 PM  
(GMT-06:00) To: 'Elecraft Reflector' <elecraft@mailman.qth.net> Subject: 
[Elecraft]  KPA500 Faulting on high SWR on power rise
I just posted almost the exact thing. I should have read all of the posts
first.

It is interesting that coax has a much higher voltage rating than the
connectors however Amphenol UHF connectors rarely fail even after direct
lightning strikes.

John KK9A

K6WRU wrote:

The Amphenol voltage rating for UHF connectors is 500 V peak. So the
connectors could be another weak point.

https://www.amphenolrf.com/connectors/uhf.html

wunder
K6WRU
Walter Under

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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[GaryK9GS]

I have never seen a properly installed UHF connector, in a matched system, arc.


73,
Gary K9GS
 Original message From: j...@kk9a.com Date: 2/24/18  5:14 PM  
(GMT-06:00) To: 'Elecraft Reflector' <elecraft@mailman.qth.net> Subject: 
[Elecraft]  KPA500 Faulting on high SWR on power rise 
I just posted almost the exact thing. I should have read all of the posts
first. 

It is interesting that coax has a much higher voltage rating than the
connectors however Amphenol UHF connectors rarely fail even after direct
lightning strikes.

John KK9A

K6WRU wrote:

The Amphenol voltage rating for UHF connectors is 500 V peak. So the
connectors could be another weak point.

https://www.amphenolrf.com/connectors/uhf.html

wunder
K6WRU
Walter Under

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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Alan]

10:1 SWR implies that the impedance is 500 ohms resistive at the maximum 
point on the line.


E = sqrt(P*R) = sqrt (500w * 500ohms) = 500 Vrms, which is 707 Vpk.

So if the UHF connector happened to be located at a voltage maximum on 
the line it would see more than its rated 500V peak.


Alan N1AL


On 02/24/2018 05:11 PM, Walter Underwood wrote:

In this case, the lightning protection is on the antenna side of the matching 
unit, so it isn’t at 1:1 SWR or 50 Ohms. At 10:1 VSWR, we would see 500 V peak 
at 500 W.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)


On Feb 24, 2018, at 4:46 PM, Bob McGraw K4TAX  wrote:

Based on the specification of 500 volts peak,5KW at 50 ohms = 500 volts.  
It would seem the PL-259 is adequate for ham radio applications per 
specification to 0.3 GHZ or 300 MHz without issues. Of course one is dealing 
with 50 ohms, which implies essentially a 1:1 SWR.

73

Bob, K4TAX

On 2/24/2018 4:53 PM, j...@kk9a.com wrote:

Really?  An Amphenol UHF connector only has a 500v rating.

John KK9A


Bill Johnson k9yeq wrote

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

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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Walter Underwood]

In this case, the lightning protection is on the antenna side of the matching 
unit, so it isn’t at 1:1 SWR or 50 Ohms. At 10:1 VSWR, we would see 500 V peak 
at 500 W. 

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Feb 24, 2018, at 4:46 PM, Bob McGraw K4TAX  wrote:
> 
> Based on the specification of 500 volts peak,5KW at 50 ohms = 500 volts.  
> It would seem the PL-259 is adequate for ham radio applications per 
> specification to 0.3 GHZ or 300 MHz without issues. Of course one is dealing 
> with 50 ohms, which implies essentially a 1:1 SWR.
> 
> 73
> 
> Bob, K4TAX
> 
> On 2/24/2018 4:53 PM, j...@kk9a.com wrote:
>> Really?  An Amphenol UHF connector only has a 500v rating.
>> 
>> John KK9A
>> 
>> 
>> Bill Johnson k9yeq wrote
>> 
>> 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
>> 
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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Bob McGraw K4TAX]

Based on the specification of 500 volts peak,    5KW at 50 ohms = 500 
volts.  It would seem the PL-259 is adequate for ham radio applications 
per specification to 0.3 GHZ or 300 MHz without issues. Of course 
one is dealing with 50 ohms, which implies essentially a 1:1 SWR.


73

Bob, K4TAX




On 2/24/2018 4:53 PM, j...@kk9a.com wrote:

Really?  An Amphenol UHF connector only has a 500v rating.

John KK9A


Bill Johnson k9yeq wrote

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

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[Elecraft] KPA500 Faulting on high SWR on power rise

[john]

I just posted almost the exact thing. I should have read all of the posts
first. 

It is interesting that coax has a much higher voltage rating than the
connectors however Amphenol UHF connectors rarely fail even after direct
lightning strikes.

John KK9A

K6WRU wrote:

The Amphenol voltage rating for UHF connectors is 500 V peak. So the
connectors could be another weak point.

https://www.amphenolrf.com/connectors/uhf.html

wunder
K6WRU
Walter Under

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[Elecraft] KPA500 Faulting on high SWR on power rise

[john]

Really?  An Amphenol UHF connector only has a 500v rating.

John KK9A


Bill Johnson k9yeq wrote 

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

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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[hawley, charles j jr]

https://www.digikey.com/product-detail/en/littelfuse-inc/CG21000/F10878-ND/2024360

Chuck Hawley
 c-haw...@illinois.edu

 Amateur Radio, KE9UW
 aka Jack, BMW Motorcycles

From: elecraft-boun...@mailman.qth.net [elecraft-boun...@mailman.qth.net] on 
behalf of Chris Hallinan [challi...@gmail.com]
Sent: Saturday, February 24, 2018 10:50 AM
To: donw...@embarqmail.com
Cc: Wes Stewart; <elecraft@mailman.qth.net>
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 <donw...@embarqmail.com>
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.
>>
>>


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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Walter Underwood]

The Amphenol voltage rating for UHF connectors is 500 V peak. So the connectors 
could be another weak point.

https://www.amphenolrf.com/connectors/uhf.html

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Feb 24, 2018, at 11:07 AM, Bill Johnson <k9...@live.com> wrote:
> 
> 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: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On 
> Behalf Of Chris Hallinan
> Sent: Saturday, February 24, 2018 10:51 AM
> To: donw...@embarqmail.com
> Cc: Wes Stewart <wes_n...@triconet.org>; <elecraft@mailman.qth.net> 
> <elecraft@mailman.qth.net>
> 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 <donw...@embarqmail.com>
> 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: [Elecraft] KPA500 Faulting on high SWR on power rise

[Bill Johnson]

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: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On 
Behalf Of Chris Hallinan
Sent: Saturday, February 24, 2018 10:51 AM
To: donw...@embarqmail.com
Cc: Wes Stewart <wes_n...@triconet.org>; <elecraft@mailman.qth.net> 
<elecraft@mailman.qth.net>
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 <donw...@embarqmail.com>
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.
>>
>>


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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Richard Stutsman]

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: [Elecraft] 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 
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.
>>
>>


-- 
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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Dave Cole (NK7Z)]

Be aware that the device on the page linked presents DC blocking to your 
feed line, at least the schematic indicates that.


If you are running an RCS-4 remote coax switch, (or any coax switch that 
runs control voltage down the coax), you will need to get a device which 
passes DC, or change switch types.  This assumes you mount them at your 
cable entrance point, and have the switch end beyond that point.


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

On 02/24/2018 08:19 AM, j...@kk9a.com wrote:

Great troubleshooting.  After a recent Elecraft post by K9YC I purchased
three of these
https://www.arraysolutions.com/surge-and-rf-protection/as-303u and I will
likely buy more as they look really nice.

John KK9A

K1AY wrote:

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

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[Elecraft] KPA500 Faulting on high SWR on power rise

[john]

Great troubleshooting.  After a recent Elecraft post by K9YC I purchased
three of these
https://www.arraysolutions.com/surge-and-rf-protection/as-303u and I will
likely buy more as they look really nice.

John KK9A

K1AY wrote:

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

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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Don Wilhelm]

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: [Elecraft] KPA500 Faulting on high SWR on power rise

[hawley, charles j jr]

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
 c-haw...@illinois.edu

 Amateur Radio, KE9UW
 aka Jack, BMW Motorcycles

From: elecraft-boun...@mailman.qth.net [elecraft-boun...@mailman.qth.net] on 
behalf of Chris Hallinan [challi...@gmail.com]
Sent: Saturday, February 24, 2018 9:32 AM
To: Wes Stewart
Cc: <elecraft@mailman.qth.net>
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 <wes_n...@triconet.org> 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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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Chris Hallinan]

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  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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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Chris Hallinan]

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  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.
>>
>>


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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Wes Stewart]

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: [Elecraft] KPA500 Faulting on high SWR on power rise

[Arthur Nienhouse]

*/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: [Elecraft] 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.
cyaffeyno_s...@gmail.com 
614 268 6353, Columbus OH
http://www.carl-yaffey.com
http://www.grassahol.com
http://www.bluesswing.com

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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Dave Cole (NK7Z)]

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: [Elecraft] KPA500 Faulting on high SWR on power rise

[Carl Yaffey]

Another possibility: There is a spurious signal on a widely different 
frequency. I experienced this.

Carl Yaffey  K8NU
Recording studio.
cyaffeyno_s...@gmail.com 
614 268 6353, Columbus OH
http://www.carl-yaffey.com
http://www.grassahol.com
http://www.bluesswing.com

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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[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).  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: [Elecraft] 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  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:
>  or this:
> 
> 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
>>
>>
>>


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

[Victor Rosenthal 4X6GP]

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:

 or this:

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: [Elecraft] KPA500 Faulting on high SWR on power rise

[Jack Brindle]

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  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.
> __
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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[Logan R Zintsmaster]

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 <garyk...@wi.rr.com> 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 <challi...@gmail.com> 
> Date: 2/23/18  11:42 PM  (GMT-06:00) To: "<elecraft@mailman.qth.net>" 
> <Elecraft@mailman.qth.net> 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: [Elecraft] KPA500 Faulting on high SWR on power rise

[Rick Bates (WA6NHC)]

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  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
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Re: [Elecraft] KPA500 Faulting on high SWR on power rise

[GaryK9GS]

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 <challi...@gmail.com> 
Date: 2/23/18  11:42 PM  (GMT-06:00) To: "<elecraft@mailman.qth.net>" 
<Elecraft@mailman.qth.net> 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


-- 
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[Elecraft] 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


-- 
Life is like Linux - it never stands still.
__
Elecraft mailing list
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Help: http://mailman.qth.net/mmfaq.htm
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