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KPA-1500 failing on 160...AGAIN!

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Peter W2IRT

KPA-1500 failing on 160...AGAIN!

My KPA is once again repeatedly failing on 160m. I haven't used it on
Topband since about the end of March, when it was fine. My antenna is
checking out fine on my AA-230 ZOOM analyzer, and I can run 100W into the
antenna from the K3s with no problem.

I'm getting FAULT: PWR REFL on every keydown with drive power at any level,
even just 5W in will cause it to fail.

I am running from the K3s directly into the KPA-1500, and from the KPA to an
antenna switch out to the antennas. Everything was 100% last time I fired
up, and the am IS working on 20 and 40 (the only other bands I've used since
March). Any idea where to start looking here? I'm at a complete loss and
have just missed two new DXCC entities on 160 as a result.

---------------------------------------------
73 and Good DX
Peter, W2IRT

President, North Jersey DX Association

DXCC Card Checker
Letter O Manager, ARRL Incoming 2nd District QSL bureau

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Lovin' my K3S (S/N 10023)
73, Peter W2IRT

Vic Rosenthal

Re: KPA-1500 failing on 160...AGAIN!

What happens with a dummy load? If it doesn’t fail, then the problem is in the antenna. The KPA may be more sensitive to a short period of high SWR than the K3.

Victor 4X6GP

> On 27 Sep 2019, at 8:26, Peter Dougherty <[hidden email]> wrote:
>
> My KPA is once again repeatedly failing on 160m. I haven't used it on
> Topband since about the end of March, when it was fine. My antenna is
> checking out fine on my AA-230 ZOOM analyzer, and I can run 100W into the
> antenna from the K3s with no problem.
>
>
> I'm getting FAULT: PWR REFL on every keydown with drive power at any level,
> even just 5W in will cause it to fail.
>
> I am running from the K3s directly into the KPA-1500, and from the KPA to an
> antenna switch out to the antennas. Everything was 100% last time I fired
> up, and the am IS working on 20 and 40 (the only other bands I've used since
> March). Any idea where to start looking here? I'm at a complete loss and
> have just missed two new DXCC entities on 160 as a result.
>
>
> ---------------------------------------------
> 73 and Good DX
> Peter, W2IRT
>
>
>
> President, North Jersey DX Association
>
> DXCC Card Checker
> Letter O Manager, ARRL Incoming 2nd District QSL bureau
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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> Message delivered to [hidden email]

Jim Brown-10

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by Peter W2IRT

On 9/26/2019 10:26 PM, Peter Dougherty wrote:
> Any idea where to start looking here?

What is the antenna? The feedline? Is the antenna resonant? Is there a
serious common mode choke at the feedpoint? (See
http://k9yc.com/2018Cookbook.pdf ) Is it matched to the feedline at the
frequency (ies) where you're trying to use it? How is the feedline
matched to the KPA? Have you used other high power amps with that
antenna? Remember that SWR is NOT a descriptor of antenna performance.
High power can expose antenna and feedline problems that are not evident
at 100W. Are there elements of the antenna that could be breaking down
with high power? Look at coax, connectors, how they are soldered, etc.
What happens at lower power (500W, for example)?

73, Jim K9YC
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Jim Brown-10

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by Peter W2IRT

On 9/26/2019 10:26 PM, Peter Dougherty wrote:
> Any idea where to start looking here?

And if it's a vertical, what about the radial system?

73, Jim K9YC
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John Langdon

Re: KPA-1500 failing on 160...AGAIN!

If it also happens with a dummy load, and the antenna analyzers shows the same graph as before for R, X, then it is likely one of the connectors between the KPA1500 output and the antenna. The one such problem I had was old jumper I had put in to add an SWR bridge/monitor. It looked okay, and was finger tight, but when I replaced it in an A/B test, the problem went away.

The other time, the antenna had changed its impedance curve, but was still 'okay' and the tuner was trying to retune for it.

73 John N5CQ

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Jim Brown
Sent: Friday, September 27, 2019 4:19 AM
To: [hidden email]
Subject: Re: [Elecraft] KPA-1500 failing on 160...AGAIN!

On 9/26/2019 10:26 PM, Peter Dougherty wrote:
> Any idea where to start looking here?

And if it's a vertical, what about the radial system?

73, Jim K9YC
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Bob McGraw - K4TAX

Re: KPA-1500 failing on 160...AGAIN!

Check for burn marks or carbon traces, both on the inside and outside, of the SO-239 connectors. These may look good with the antenna analyzer but fail under power.

I've also had PL-259's arc from center pin to shell on the inside. These required removal/ disassembly of the coax in order to actually find the fault.

In all cases, once a flashover occurs, replacement of the connector is the only solution.

Bob, K4TAX

Sent from my iPhone

> On Sep 27, 2019, at 6:00 AM, John Langdon <[hidden email]> wrote:
>
> If it also happens with a dummy load, and the antenna analyzers shows the same graph as before for R, X, then it is likely one of the connectors between the KPA1500 output and the antenna. The one such problem I had was old jumper I had put in to add an SWR bridge/monitor. It looked okay, and was finger tight, but when I replaced it in an A/B test, the problem went away.
>
> The other time, the antenna had changed its impedance curve, but was still 'okay' and the tuner was trying to retune for it.
>
> 73 John N5CQ
>
>
> -----Original Message-----
> From: [hidden email] <[hidden email]> On Behalf Of Jim Brown
> Sent: Friday, September 27, 2019 4:19 AM
> To: [hidden email]
> Subject: Re: [Elecraft] KPA-1500 failing on 160...AGAIN!
>
>> On 9/26/2019 10:26 PM, Peter Dougherty wrote:
>> Any idea where to start looking here?
>
> And if it's a vertical, what about the radial system?
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
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Michael Walker

Re: KPA-1500 failing on 160...AGAIN!

Like others have said

Even though your analyzer says the antenna is ok, that is only one part.
It can still be part of the problem at 1500 watts and if memory serves me
well, that is about 275V (RMS) at 50 ohms.

Something could be breaking down at that voltage so a good visual
inspection would help. Look for arcing at each connector, Ununs, Baluns,
etc.

Mike va3mw

On Fri, Sep 27, 2019 at 9:18 AM Bob McGraw K4TAX <[hidden email]>
wrote:

> Check for burn marks or carbon traces, both on the inside and outside, of
> the SO-239 connectors. These may look good with the antenna analyzer but
> fail under power.
>
> I've also had PL-259's arc from center pin to shell on the inside. These
> required removal/ disassembly of the coax in order to actually find the
> fault.
>
> In all cases, once a flashover occurs, replacement of the connector is the
> only solution.
>
> Bob, K4TAX
>
>
> Sent from my iPhone
>
> > On Sep 27, 2019, at 6:00 AM, John Langdon <[hidden email]> wrote:
> >
> > If it also happens with a dummy load, and the antenna analyzers shows
> the same graph as before for R, X, then it is likely one of the connectors
> between the KPA1500 output and the antenna. The one such problem I had was
> old jumper I had put in to add an SWR bridge/monitor. It looked okay, and
> was finger tight, but when I replaced it in an A/B test, the problem went
> away.
> >
> > The other time, the antenna had changed its impedance curve, but was
> still 'okay' and the tuner was trying to retune for it.
> >
> > 73 John N5CQ
> >
> >
> > -----Original Message-----
> > From: [hidden email] <[hidden email]>
> On Behalf Of Jim Brown
> > Sent: Friday, September 27, 2019 4:19 AM
> > To: [hidden email]
> > Subject: Re: [Elecraft] KPA-1500 failing on 160...AGAIN!
> >
> >> On 9/26/2019 10:26 PM, Peter Dougherty wrote:
> >> Any idea where to start looking here?
> >
> > And if it's a vertical, what about the radial system?
> >
> > 73, Jim K9YC
> > ______________________________________________________________
> > 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]
> > ______________________________________________________________
> > 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
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> > Message delivered to [hidden email]
> >
>
>
> ______________________________________________________________
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Jim AB3CV

Re: KPA-1500 failing on 160...AGAIN!

Although the RMS voltage is pretty high. The peak voltage is higher
especially if SWR isn't 1:1 along the transmission line.

It could easily be above 1Kv and causing arcing.

73

jim ab3cv

On Fri, Sep 27, 2019 at 10:35 AM Michael Walker <[hidden email]>
wrote:

> Like others have said
>
> Even though your analyzer says the antenna is ok, that is only one part.
> It can still be part of the problem at 1500 watts and if memory serves me
> well, that is about 275V (RMS) at 50 ohms.
>
> Something could be breaking down at that voltage so a good visual
> inspection would help. Look for arcing at each connector, Ununs, Baluns,
> etc.
>
> Mike va3mw
>
> On Fri, Sep 27, 2019 at 9:18 AM Bob McGraw K4TAX <[hidden email]>
> wrote:
>
> > Check for burn marks or carbon traces, both on the inside and outside,
> of
> > the SO-239 connectors. These may look good with the antenna analyzer but
> > fail under power.
> >
> > I've also had PL-259's arc from center pin to shell on the inside. These
> > required removal/ disassembly of the coax in order to actually find the
> > fault.
> >
> > In all cases, once a flashover occurs, replacement of the connector is
> the
> > only solution.
> >
> > Bob, K4TAX
> >
> >
> > Sent from my iPhone
> >
> > > On Sep 27, 2019, at 6:00 AM, John Langdon <[hidden email]>
> wrote:
> > >
> > > If it also happens with a dummy load, and the antenna analyzers shows
> > the same graph as before for R, X, then it is likely one of the
> connectors
> > between the KPA1500 output and the antenna. The one such problem I had
> was
> > old jumper I had put in to add an SWR bridge/monitor. It looked okay, and
> > was finger tight, but when I replaced it in an A/B test, the problem went
> > away.
> > >
> > > The other time, the antenna had changed its impedance curve, but was
> > still 'okay' and the tuner was trying to retune for it.
> > >
> > > 73 John N5CQ
> > >
> > >
> > > -----Original Message-----
> > > From: [hidden email] <
> [hidden email]>
> > On Behalf Of Jim Brown
> > > Sent: Friday, September 27, 2019 4:19 AM
> > > To: [hidden email]
> > > Subject: Re: [Elecraft] KPA-1500 failing on 160...AGAIN!
> > >
> > >> On 9/26/2019 10:26 PM, Peter Dougherty wrote:
> > >> Any idea where to start looking here?
> > >
> > > And if it's a vertical, what about the radial system?
> > >
> > > 73, Jim K9YC
> > > ______________________________________________________________
> > > 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]
> > > ______________________________________________________________
> > > 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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john@kk9a.com

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by Peter W2IRT

5000 watts is 500 volts rms with a perfect antenna system. I suspect
that PL-259 connectors really can withstand much more than 500 volts.
Has anyone tested them? My station has a mixture of UHF, N and DIN
connectors and all have worked perfectly for 1500 watts HF. If
PL-259s are failing they are either poor quality connectors or there
are serious antenna issues causing excessive voltage.

John KK9A

Walter Underwood K6WRU

Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
From the Amphenol data sheet, UHF connectors are rated for 500 V
peak, so they are marginal for use at that power level. Type N
connectors are rated at 1500 V peak.

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

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Jeff Blaine

Re: KPA-1500 failing on 160...AGAIN!

PL259/SO239 BDV is around 4KV in dry air.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 9/27/19 1:01 PM, [hidden email] wrote:

> 5000 watts is 500 volts rms with a perfect antenna system. I suspect
> that PL-259 connectors really can withstand much more than 500 volts.
> Has anyone tested them? My station has a mixture of UHF, N and DIN
> connectors and all have worked perfectly for 1500 watts HF. If
> PL-259s are failing they are either poor quality connectors or there
> are serious antenna issues causing excessive voltage.
>
> John KK9A
>
>
> Walter Underwood K6WRU
>
> Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
> From the Amphenol data sheet, UHF connectors are rated for 500 V peak,
> so they are marginal for use at that power level. Type N connectors
> are rated at 1500 V peak.
>
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> 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]

Bob McGraw - K4TAX

Re: KPA-1500 failing on 160...AGAIN!

Yes and without proper lightning protection or static build-up
prevention on a feedline, a nearby strike can induce 4KV+ on the antenna
and feedline. A flash-over will likely leave a carbon trace that will
be followed by a few 100 watts of RF.   It only gets worst, not
better.   On more than one occasion I've heard a snap snap only to
observe a spark occurring between the shell and center pin of a
PL-259.   This was before I installed PolyPhaser devices on the lines
and before I stopped disconnecting my feed lines from the equipment.
Since then, no issues.

73

Bob, K4TAX

On 9/27/2019 1:04 PM, Jeff Blaine wrote:

> PL259/SO239 BDV is around 4KV in dry air.
>
> 73/jeff/ac0c
> alpha-charlie-zero-charlie
> www.ac0c.com
>
>
> On 9/27/19 1:01 PM, [hidden email] wrote:
>> 5000 watts is 500 volts rms with a perfect antenna system. I suspect
>> that PL-259 connectors really can withstand much more than 500 volts.
>> Has anyone tested them? My station has a mixture of UHF, N and DIN
>> connectors and all have worked perfectly for 1500 watts HF. If
>> PL-259s are failing they are either poor quality connectors or there
>> are serious antenna issues causing excessive voltage.
>>
>> John KK9A
>>
>>
>> Walter Underwood K6WRU
>>
>> Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
>> From the Amphenol data sheet, UHF connectors are rated for 500 V
>> peak, so they are marginal for use at that power level. Type N
>> connectors are rated at 1500 V peak.
>>
>>
>> wunder
>> K6WRU
>> Walter Underwood
>> CM87wj
>> http://observer.wunderwood.org/ (my blog)
>>
>> ______________________________________________________________
>> 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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Jim Brown-10

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by john@kk9a.com

On 9/27/2019 11:01 AM, [hidden email] wrote:
> If PL-259s are failing they are either poor quality connectors or there
> are serious antenna issues causing excessive voltage.

YES! Only first quality connectors and adapters should be used.

I run legal limit to resonant antennas fed with 50 ohm and 75 ohm coax
and hard line. Amphenol 83-1SP connectors are the standard throughout my
station. I use type N only on hard line for which UHF connectors are not
available. I've NEVER experienced any symptoms of arcing in connectors.

I HAVE seen lots problems caused by poor quality connectors and
adapters, and by poorly soldered coax connectors when putting stations
together for Field Day and similar operations.

My rule: In North America, if the connector doesn't say Amphenol 83-1SP
or have a MIL spec number stamped on it, it is JUNK. The same holds true
for adapters.

73, Jim K9YC
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Jeff Blaine

Re: KPA-1500 failing on 160...AGAIN!

I don't doubt the AMP connector is great but doubt this issue is due to
a connector.

One thing I can say from personal experience is that if you have a tall
or long antenna, you definitely need a static bleed on that bad boy.
Never really gave those stories much credence but a number of years back
I was doing some work on an 80m full size vert one summer. Managed at
one point to to reach up and touch a wire that was hanging off the
vertical - and landed up on my butt from the jolt. So that static build
up thing is real. Been using high value high power wire wound resistors
for bleeding since. And a polyphaser to provide the discharge path in
the event the voltage builds up too high from a nearby strike or whatever.

The 1500 has PIN diodes for switching. Generically speaking running a
PIN diode switched amp without a spark gap on the coax to clamp spikes
from whatever cause seems like tempting fate one step too close. Maybe
the 1500 has some internal protection - don't hear much about a lot of
switching failure on the amp. But a GDT pass through like a polyphaser
is cheap insurance.

PS: CQ WW RTTY starts tonight!!!!!!!!!!!!!!!

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 9/27/19 1:48 PM, Jim Brown wrote:

> On 9/27/2019 11:01 AM, [hidden email] wrote:
>> If PL-259s are failing they are either poor quality connectors or
>> there are serious antenna issues causing excessive voltage.
>
> YES! Only first quality connectors and adapters should be used.
>
> I run legal limit to resonant antennas fed with 50 ohm and 75 ohm coax
> and hard line. Amphenol 83-1SP connectors are the standard throughout
> my station. I use type N only on hard line for which UHF connectors
> are not available. I've NEVER experienced any symptoms of arcing in
> connectors.
>
> I HAVE seen lots problems caused by poor quality connectors and
> adapters, and by poorly soldered coax connectors when putting stations
> together for Field Day and similar operations.
>
> My rule: In North America, if the connector doesn't say Amphenol
> 83-1SP or have a MIL spec number stamped on it, it is JUNK. The same
> holds true for adapters.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Michael Walker

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by Jim Brown-10

I'm going to partially disagree with Jim :)

I agree on good quality connectors, when you have them.

I can honestly say I have yet to have a none-Amphenol fail since I learned
to solder them in 1972.

I can also honestly say I have had a connector fail when I did not assembly
it correctly. This would be both Amphenol and non-Amphenol. PEBKAC

We all know how this discussion is going to go now

:)

Mike va3mw

On Fri, Sep 27, 2019 at 2:49 PM Jim Brown <[hidden email]> wrote:

> On 9/27/2019 11:01 AM, [hidden email] wrote:
> > If PL-259s are failing they are either poor quality connectors or there
> > are serious antenna issues causing excessive voltage.
>
> YES! Only first quality connectors and adapters should be used.
>
> I run legal limit to resonant antennas fed with 50 ohm and 75 ohm coax
> and hard line. Amphenol 83-1SP connectors are the standard throughout my
> station. I use type N only on hard line for which UHF connectors are not
> available. I've NEVER experienced any symptoms of arcing in connectors.
>
> I HAVE seen lots problems caused by poor quality connectors and
> adapters, and by poorly soldered coax connectors when putting stations
> together for Field Day and similar operations.
>
> My rule: In North America, if the connector doesn't say Amphenol 83-1SP
> or have a MIL spec number stamped on it, it is JUNK. The same holds true
> for adapters.
>
> 73, Jim K9YC
> ______________________________________________________________
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Jim Brown-10

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by Jeff Blaine

On 9/27/2019 12:00 PM, Jeff Blaine wrote:
> One thing I can say from personal experience is that if you have a tall
> or long antenna, you definitely need a static bleed on that bad boy.

YES! After experiencing multiple shorts of Polyphaser arrestors on high
wires, I've switched to the arrestors that Array Solutions sells because
1) they provide a discharge path AND 2) because they are built in a
manner that their GDT can be replaced.

73, Jim K9YC
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K8TE

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by Jeff Blaine

For those with insulated verticals, the potential gradient is about 100
V/meter. That varies with humidity and altitude. But, you get the picture.
In dry climates like here in NM, this is a big deal for commercial broadcast
AM antennas. Even with the transmitter shut down, unless there is a "DC
ground" on the antenna, one shorts the tower to ground first prior to
climbing on or off the tower. This was a big deal when the local power
company rescued three folks from our 770 tower after it "captured" their hot
air balloon!

Bleeding off static electricity is a big deal. Wind blowing dust, snow, or
rain can generate thousands of Volts that can provide a mean shock to us
humans and hurt our radio gear. I am leaving for the race track to play
with my Miata this weekend. I will disconnect my antennas, just in case.

73, Bill, K8TE

--
Sent from: http://elecraft.365791.n2.nabble.com/
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Jeff Blaine

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by Jeff Blaine

It's from my head. I have a BVT - it's DC so the 4K is a DC claim. I
BVT cables used here in the shack as a fast way to ensure I don't have
some microscopic wire or filing or whatever down in a connector - stuff
like that is a nightmare to troubleshoot.

At one point I tried to use a PL259 for a HV run but it arced from time
to time at 4.2KV.

So at least in this shack, a PL259/SO239 is rated for well under 4KV.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 9/27/19 3:14 PM, Walter Underwood wrote:

> Few of us can guarantee dry air for our antenna connections. Where is this data from?
>
> For the question “Has anyone tested them?”, I expect that Amphenol tests to the published specs. Those tests would be over the entire temperature range in the data sheet. If you visit the data sheets I linked for the UHF and type N connectors, you might notice that type N has spect for many more attributes than UHF.
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
>> On Sep 27, 2019, at 11:04 AM, Jeff Blaine <[hidden email]> wrote:
>>
>> PL259/SO239 BDV is around 4KV in dry air.
>>
>> 73/jeff/ac0c
>> alpha-charlie-zero-charlie
>> www.ac0c.com
>>
>>
>> On 9/27/19 1:01 PM, [hidden email] wrote:
>>> 5000 watts is 500 volts rms with a perfect antenna system. I suspect that PL-259 connectors really can withstand much more than 500 volts. Has anyone tested them? My station has a mixture of UHF, N and DIN connectors and all have worked perfectly for 1500 watts HF. If PL-259s are failing they are either poor quality connectors or there are serious antenna issues causing excessive voltage.
>>>
>>> John KK9A
>>>
>>>
>>> Walter Underwood K6WRU
>>>
>>> Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
>>> From the Amphenol data sheet, UHF connectors are rated for 500 V peak, so they are marginal for use at that power level. Type N connectors are rated at 1500 V peak.
>>>
>>>
>>> wunder
>>> K6WRU
>>> Walter Underwood
>>> CM87wj
>>> http://observer.wunderwood.org/ (my blog)
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
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David Gilbert

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by K8TE

I've probably posted this here before, but I once had a 160m Inverted-V
at 70 feet that didn't have a DC ground. As a thunderstorm approached
(but was still several miles away) I reached down to short the coax end
in the shack and drew a heavy blue 2 inch long arc that traveled from
the end of the coax into my left arm and out my right arm to the
concrete floor. My biceps were sore for three days.

The breakdown inception voltage of 2 inches of dry air is generally
considered to be over 150,000 volts.

73,
Dave AB7E

On 9/27/2019 1:59 PM, K8TE wrote:

> For those with insulated verticals, the potential gradient is about 100
> V/meter. That varies with humidity and altitude. But, you get the picture.
> In dry climates like here in NM, this is a big deal for commercial broadcast
> AM antennas. Even with the transmitter shut down, unless there is a "DC
> ground" on the antenna, one shorts the tower to ground first prior to
> climbing on or off the tower. This was a big deal when the local power
> company rescued three folks from our 770 tower after it "captured" their hot
> air balloon!
>
> Bleeding off static electricity is a big deal. Wind blowing dust, snow, or
> rain can generate thousands of Volts that can provide a mean shock to us
> humans and hurt our radio gear. I am leaving for the race track to play
> with my Miata this weekend. I will disconnect my antennas, just in case.
>
> 73, Bill, K8TE
>

Bill K9YEQ

Re: KPA-1500 failing on 160...AGAIN!

To that end, I use a remote switch to remove direct connection and have all the grounding to an extensive ground system to to all my ground side connectors to attract any static to ground without shorting or providing any direct path to my shack.

Bill
920-421-1172

________________________________
From: [hidden email] <[hidden email]> on behalf of David Gilbert <[hidden email]>
Sent: Friday, September 27, 2019 4:45:55 PM
To: [hidden email] <[hidden email]>
Subject: Re: [Elecraft] KPA-1500 failing on 160...AGAIN!

I've probably posted this here before, but I once had a 160m Inverted-V
at 70 feet that didn't have a DC ground. As a thunderstorm approached
(but was still several miles away) I reached down to short the coax end
in the shack and drew a heavy blue 2 inch long arc that traveled from
the end of the coax into my left arm and out my right arm to the
concrete floor. My biceps were sore for three days.

The breakdown inception voltage of 2 inches of dry air is generally
considered to be over 150,000 volts.

73,
Dave AB7E

On 9/27/2019 1:59 PM, K8TE wrote:

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alorona

Re: KPA-1500 failing on 160...AGAIN!

In reply to this post by Jim Brown-10

And not just antenna and feedlines, but the AC wiring in your shack, the potential EMI problems, etc. This is why I keep saying that hams badly need a tutorial -- perhaps something named, "What to Expect When You Run High Power". There are lots of us, including me, that could learn about the extra precautions and checks one needs to make when you put an amplifier into service. Jim, maybe you're the right guy to do it?

>>>High power can expose antenna and feedline problems that are not evident
>>>at 100W.

>>>73, Jim K9YC
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