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KPA 500

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Alan - G4GNX

KPA 500

I have a strange fault a couple of times recently, where the SWR starts
to increase during the time of a single 'over'. I've been using the K3S
set at 100W out, via the KPA500 (in standby) and the KAT500 tuner,
without any problem, but after I've switched the linear to Operate and
driving it to 200W, the SWR creeps up. I don't think it's an antenna
issue, but a possible heat problem with the KPA500. I watched the
temperature display on the KPA500 and initially on Standby it shows
about 38 degrees C. After transmitting at 200W the temperature slowly
rises above 60 degrees C, but the fan doesn't cut in. Does anyone know
if this is normal behavior and what temperatures I should expect to see?
I have tested the fan via the Menu function and it works as expected.

73,

Alan. G4GNX

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Lyn WØLEN

Re: KPA 500

At 100w on 20m, my KAT500 Utility shows an SWR of 1.00 with the KPA500 on
Standby and temp around 38ºC. But as I switch the KPA to Operate and
increase the power to 300w the SWR goes up as high as 1.10. If I hold it
there (key down) long enough the KPA temp starts rising slowly. At about
50ºC I can hear the fan picking up speed. By the time I get to 60ºC the fan
is at probably level 2 or 3. SWR is still at 1.10 (max).
Right or wrong, I've always assumed there is some slight heating in the
antenna system (Tuner, Balun, Lightning protection) although all components
after the tuner are rated at 5 KW.
73
Lyn, WØLEN

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Alan - G4GNX
Sent: Friday, April 10, 2020 6:27 AM
To: Elecraft Reflector
Subject: [Elecraft] KPA 500

I have a strange fault a couple of times recently, where the SWR starts
to increase during the time of a single 'over'. I've been using the K3S
set at 100W out, via the KPA500 (in standby) and the KAT500 tuner,
without any problem, but after I've switched the linear to Operate and
driving it to 200W, the SWR creeps up. I don't think it's an antenna
issue, but a possible heat problem with the KPA500. I watched the
temperature display on the KPA500 and initially on Standby it shows
about 38 degrees C. After transmitting at 200W the temperature slowly
rises above 60 degrees C, but the fan doesn't cut in. Does anyone know
if this is normal behavior and what temperatures I should expect to see?
I have tested the fan via the Menu function and it works as expected.

73,

Alan. G4GNX

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Vic Rosenthal

Re: KPA 500

In reply to this post by Alan - G4GNX

I would be more likely to suspect something after the KPA500, such as
the tuner or a balun. I've experienced significant balun heating,
especially when using a balun other than a straight-through 1:1 balun,
or when the load is highly reactive. Balun power ratings assume a
non-reactive load.

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
On 10/04/2020 14:26, Alan - G4GNX wrote:

>
> I have a strange fault a couple of times recently, where the SWR starts
> to increase during the time of a single 'over'. I've been using the K3S
> set at 100W out, via the KPA500 (in standby) and the KAT500 tuner,
> without any problem, but after I've switched the linear to Operate and
> driving it to 200W, the SWR creeps up. I don't think it's an antenna
> issue, but a possible heat problem with the KPA500. I watched the
> temperature display on the KPA500 and initially on Standby it shows
> about 38 degrees C. After transmitting at 200W the temperature slowly
> rises above 60 degrees C, but the fan doesn't cut in. Does anyone know
> if this is normal behavior and what temperatures I should expect to see?
> I have tested the fan via the Menu function and it works as expected.
>
> 73,
>
> Alan. G4GNX
>
> ______________________________________________________________
> 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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Mark Goldberg

Re: KPA 500

My experience is that slowly increasing SWR is from a component heating up,
usually an inductor in a tuner or balun. You don't see it with lower power.
Ferrite cores change their inductance radically as they heat up near their
Curie temperature. If they get to their Curie temperature, they lost their
magnetic properties. As the SWR goes up, they get even hotter, SWR goes up
more and if you don't stop transmitting, they will fail.

All SWRs with the same number are not equal in terms of losses in a tuner
or balun. As Victor described, when the load it highly reactive, there are
more losses in the tuner or balun. If you have an IR thermometer, you
should be able to point it at inductors and see what is getting hot.

I've got a horizontal loop that is slightly too small for 160. I have an
added shunt inductor in the line to allow my tuner to tune it, but the
inductor, which is on a 2.4" core still gets hot. Most tuners have smaller
inductors than that. My home built balun also has 2.4" cores. Many baluns
use smaller cores.

73,

Mark
W7MLG

On Fri, Apr 10, 2020 at 7:16 AM Victor Rosenthal 4X6GP <[hidden email]>
wrote:

> I would be more likely to suspect something after the KPA500, such as
> the tuner or a balun. I've experienced significant balun heating,
> especially when using a balun other than a straight-through 1:1 balun,
> or when the load is highly reactive. Balun power ratings assume a
> non-reactive load.
>
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> Formerly K2VCO
> CWops no. 5
> http://www.qsl.net/k2vco/
> On 10/04/2020 14:26, Alan - G4GNX wrote:
> >
> > I have a strange fault a couple of times recently, where the SWR starts
> > to increase during the time of a single 'over'. I've been using the K3S
> > set at 100W out, via the KPA500 (in standby) and the KAT500 tuner,
> > without any problem, but after I've switched the linear to Operate and
> > driving it to 200W, the SWR creeps up. I don't think it's an antenna
> > issue, but a possible heat problem with the KPA500. I watched the
> > temperature display on the KPA500 and initially on Standby it shows
> > about 38 degrees C. After transmitting at 200W the temperature slowly
> > rises above 60 degrees C, but the fan doesn't cut in. Does anyone know
> > if this is normal behavior and what temperatures I should expect to see?
> > I have tested the fan via the Menu function and it works as expected.
> >
> > 73,
> >
> > Alan. G4GNX
> >
> > ______________________________________________________________
> > 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
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>
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> Message delivered to [hidden email]
>

Don Wilhelm

Re: KPA 500

In reply to this post by Alan - G4GNX

Alan,

That does sound like an antenna problem - balun heating, a loose or bad
connection somewhere.

Try that same test into a dummy load - if it shows the same behavior,
then you can blame the KPA500, but if not blame the antenna system.

73,
Don W3FPR

On 4/10/2020 7:26 AM, Alan - G4GNX wrote:

Randy Farmer-2

Re: KPA 500

In reply to this post by Lyn WØLEN

If the initial VSWR is really measuring 1.00:1 with low power, that
means the detected reflected power is exceptionally low. I'm sure the
algorithm used to compute SWR sets it to 1:1 if there's zero reflected
power. If the load is not really perfectly flat, as the incident power
is increased the detector will finally see enough reflected energy to
give an indication. You have absolutely nothing to worry about in your
system.

73...
Randy, W8FN

On 4/10/2020 9:59 AM, Lyn Norstad wrote:

Wes Stewart-2

Re: KPA 500

In reply to this post by Lyn WØLEN

I think this is a lot of worry about normal behavior.

Although it's not directly discussed, some insight might be gleaned by reading
through this old thread:

http://elecraft.365791.n2.nabble.com/K3-SWR-Numerical-Indication-td7643839.html

Wes N7WS

On 4/10/2020 6:59 AM, Lyn Norstad wrote:

> At 100w on 20m, my KAT500 Utility shows an SWR of 1.00 with the KPA500 on
> Standby and temp around 38ºC. But as I switch the KPA to Operate and
> increase the power to 300w the SWR goes up as high as 1.10. If I hold it
> there (key down) long enough the KPA temp starts rising slowly. At about
> 50ºC I can hear the fan picking up speed. By the time I get to 60ºC the fan
> is at probably level 2 or 3. SWR is still at 1.10 (max).
> Right or wrong, I've always assumed there is some slight heating in the
> antenna system (Tuner, Balun, Lightning protection) although all components
> after the tuner are rated at 5 KW.
> 73
> Lyn, WØLEN
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Alan - G4GNX
> Sent: Friday, April 10, 2020 6:27 AM
> To: Elecraft Reflector
> Subject: [Elecraft] KPA 500
>
>
> I have a strange fault a couple of times recently, where the SWR starts
> to increase during the time of a single 'over'. I've been using the K3S
> set at 100W out, via the KPA500 (in standby) and the KAT500 tuner,
> without any problem, but after I've switched the linear to Operate and
> driving it to 200W, the SWR creeps up. I don't think it's an antenna
> issue, but a possible heat problem with the KPA500. I watched the
> temperature display on the KPA500 and initially on Standby it shows
> about 38 degrees C. After transmitting at 200W the temperature slowly
> rises above 60 degrees C, but the fan doesn't cut in. Does anyone know
> if this is normal behavior and what temperatures I should expect to see?
> I have tested the fan via the Menu function and it works as expected.
>
> 73,
>
> Alan. G4GNX
>

Ted Edwards W3TB

Re: KPA 500

In reply to this post by Randy Farmer-2

I am watching this with great interest. If running stations on CW my
KPA500 shows low-mid 50sC and I have never known what it should be. Thanks
everyone.

On Fri, Apr 10, 2020 at 10:27 Randy Farmer <[hidden email]> wrote:

> If the initial VSWR is really measuring 1.00:1 with low power, that
> means the detected reflected power is exceptionally low. I'm sure the
> algorithm used to compute SWR sets it to 1:1 if there's zero reflected
> power. If the load is not really perfectly flat, as the incident power
> is increased the detector will finally see enough reflected energy to
> give an indication. You have absolutely nothing to worry about in your
> system.
>
> 73...
> Randy, W8FN
>
>
> On 4/10/2020 9:59 AM, Lyn Norstad wrote:
> > At 100w on 20m, my KAT500 Utility shows an SWR of 1.00 with the KPA500 on
> > Standby and temp around 38ºC. But as I switch the KPA to Operate and
> > increase the power to 300w the SWR goes up as high as 1.10. If I hold it
> > there (key down) long enough the KPA temp starts rising slowly. At about
> > 50ºC I can hear the fan picking up speed. By the time I get to 60ºC the
> fan
> > is at probably level 2 or 3. SWR is still at 1.10 (max).
> > Right or wrong, I've always assumed there is some slight heating in the
> > antenna system (Tuner, Balun, Lightning protection) although all
> components
> > after the tuner are rated at 5 KW.
> > 73
> > Lyn, WØLEN
> ______________________________________________________________
> 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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> Message delivered to [hidden email]

--
73 de Ted Edwards, W3TB and GØPWW

and thinking about operating CW:
"Do today what others won't,
so you can do tomorrow what others can't."
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Irwin KD3TB

Re: KPA 500

In reply to this post by Don Wilhelm

In my experience, coax connectors, barrel connectors, etc. are always fail
points when there is a sudden increase in SWR as power is increased. They
oxidize over time and sometimes just reconnecting or replacing is the first
step before taking the amp apart.

Irwin KD3TB

On Fri, Apr 10, 2020 at 11:24 AM Don Wilhelm <[hidden email]> wrote:

> Alan,
>
> That does sound like an antenna problem - balun heating, a loose or bad
> connection somewhere.
>
> Try that same test into a dummy load - if it shows the same behavior,
> then you can blame the KPA500, but if not blame the antenna system.
>
> 73,
> Don W3FPR
>
> On 4/10/2020 7:26 AM, Alan - G4GNX wrote:
> >
> > I have a strange fault a couple of times recently, where the SWR starts
> > to increase during the time of a single 'over'. I've been using the K3S
> > set at 100W out, via the KPA500 (in standby) and the KAT500 tuner,
> > without any problem, but after I've switched the linear to Operate and
> > driving it to 200W, the SWR creeps up. I don't think it's an antenna
> > issue, but a possible heat problem with the KPA500. I watched the
> > temperature display on the KPA500 and initially on Standby it shows
> > about 38 degrees C. After transmitting at 200W the temperature slowly
> > rises above 60 degrees C, but the fan doesn't cut in. Does anyone know
> > if this is normal behavior and what temperatures I should expect to see?
> > I have tested the fan via the Menu function and it works as expected.
> >
> ______________________________________________________________
> 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]
>

--
Irwin KD3TB
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Jim Brown-10

Re: KPA 500

On 4/10/2020 8:45 AM, Irwin Darack wrote:
> In my experience, coax connectors, barrel connectors, etc. are always fail
> points when there is a sudden increase in SWR as power is increased. They
> oxidize over time and sometimes just reconnecting or replacing is the first
> step before taking the amp apart.

If this is happening, I'd suspect 1) the connectors have gotten wet or
2) the are JUNK connectors. If they aren't labeled "Amphenol," they're JUNK.

73, Jim K9YC
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Irwin KD3TB

Re: KPA 500

Agreed. Many people buy the cheap ones made in China....and they fail.

Irwin KD3TB

On Fri, Apr 10, 2020 at 12:28 PM Jim Brown <[hidden email]>
wrote:

> On 4/10/2020 8:45 AM, Irwin Darack wrote:
> > In my experience, coax connectors, barrel connectors, etc. are always
> fail
> > points when there is a sudden increase in SWR as power is increased. They
> > oxidize over time and sometimes just reconnecting or replacing is the
> first
> > step before taking the amp apart.
>
> If this is happening, I'd suspect 1) the connectors have gotten wet or
> 2) the are JUNK connectors. If they aren't labeled "Amphenol," they're
> JUNK.
>
> 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
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> Message delivered to [hidden email]
>

Bob McGraw - K4TAX

Re: KPA 500

In reply to this post by Alan - G4GNX

My first question is "what does it do on a dummy load?" Sounds like
something related to a bad or questionable jumper cable, loose connector
or bad connectors.   I find many of today's connectors have machining
tolerance errors and more so, have only "good looking" plating. While
in fact, many of these are poor quality.

I find that PL-259 connectors must be mated correctly in that the body
of the connector has 2 small triangle shaped protrusions from the body
of the connector that must be mated with the notches on the SO-239
connector.   Failure to do this will allow the connector to loosen under
use.   And then the shell of the connector must be tightened a bit more
than finger tight.   I keep a 4" pair of Channel Locks on the desk to
help remove and tighten connectors.   If not done so, the heating and
cooling of the connector will allow it to loosen and not make good contact.

Regarding the KPA500 temperature: With my amp this morning { S/N 3519
Firmware 01.54 } at turn on 18C, I then held it at 500 watts carrier
output into a 50 ohm dummy load. At 50C fan on 1 speed, at 55C fan on 2
speed.   This took about 210 seconds (3.5 minutes) from cold start to
55C on 80M into the dummy load. Other bands are less efficient and one
could expect a faster temperature rise in less time. It does vary from
band to band and antenna load to load. I did not observe any change in
SWR indication, either on the amp LED display or my Bird 43 between the
amp output and the dummy load.

Hope this helps.

73

Bob, K4TAX

On 4/10/2020 6:26 AM, Alan - G4GNX wrote:

>
> I have a strange fault a couple of times recently, where the SWR
> starts to increase during the time of a single 'over'. I've been using
> the K3S set at 100W out, via the KPA500 (in standby) and the KAT500
> tuner, without any problem, but after I've switched the linear to
> Operate and driving it to 200W, the SWR creeps up. I don't think it's
> an antenna issue, but a possible heat problem with the KPA500. I
> watched the temperature display on the KPA500 and initially on Standby
> it shows about 38 degrees C. After transmitting at 200W the
> temperature slowly rises above 60 degrees C, but the fan doesn't cut
> in. Does anyone know if this is normal behavior and what temperatures
> I should expect to see? I have tested the fan via the Menu function
> and it works as expected.
>
> 73,
>
> Alan. G4GNX
>
> ______________________________________________________________
> 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]

Buck

Re: KPA 500

In reply to this post by Irwin KD3TB

A vendor at Dayton told me *all* are made in China, even the ones marked
Amphenol.

k4ia, Buck
K3s# 11497
Honor Roll 8B DXCC
EasyWayHamBooks.com

On 4/10/2020 12:43 PM, Irwin Darack wrote:

> Agreed. Many people buy the cheap ones made in China....and they fail.
>
> Irwin KD3TB
>
> On Fri, Apr 10, 2020 at 12:28 PM Jim Brown <[hidden email]>
> wrote:
>
>> On 4/10/2020 8:45 AM, Irwin Darack wrote:
>>> In my experience, coax connectors, barrel connectors, etc. are always
>> fail
>>> points when there is a sudden increase in SWR as power is increased. They
>>> oxidize over time and sometimes just reconnecting or replacing is the
>> first
>>> step before taking the amp apart.
>>
>> If this is happening, I'd suspect 1) the connectors have gotten wet or
>> 2) the are JUNK connectors. If they aren't labeled "Amphenol," they're
>> JUNK.
>>
>> 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]
>>
>
>

NK7Z

Re: KPA 500

Amphenol more than likely does QC... So I would expect the majority of
their connectors to be better than the possibly non QC tested
connectors. I doubt most resellers QC the connectors. I am sure some
do, but I would love to know which ones do.

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

On 4/10/20 10:19 AM, Buck wrote:

> A vendor at Dayton told me *all* are made in China, even the ones marked
> Amphenol.
>
> k4ia, Buck
> K3s# 11497
> Honor Roll 8B DXCC
> EasyWayHamBooks.com
>
> On 4/10/2020 12:43 PM, Irwin Darack wrote:
>> Agreed. Many people buy the cheap ones made in China....and they fail.
>>
>> Irwin KD3TB
>>
>> On Fri, Apr 10, 2020 at 12:28 PM Jim Brown <[hidden email]>
>> wrote:
>>
>>> On 4/10/2020 8:45 AM, Irwin Darack wrote:
>>>> In my experience, coax connectors, barrel connectors, etc. are always
>>> fail
>>>> points when there is a sudden increase in SWR as power is increased.
>>>> They
>>>> oxidize over time and sometimes just reconnecting or replacing is the
>>> first
>>>> step before taking the amp apart.
>>>
>>> If this is happening, I'd suspect 1) the connectors have gotten wet or
>>> 2) the are JUNK connectors. If they aren't labeled "Amphenol," they're
>>> JUNK.
>>>
>>> 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]
>>>
>>
>>
> ______________________________________________________________
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Bob McGraw - K4TAX

Re: KPA 500

In reply to this post by Buck

I try and spend the time to recover OLD PL-259 connectors. I have some
which I've owned for 30 to 40 years. They are ugly, tarnished, and may
have phenolic insulators........but are darn good connectors. When I
encounter a bad or connector, I usually chop the connector off with
about 1" of cable remaining and toss it in a box. Speaking of which,
I'd say there are 10 to 15 pieces of RG-8 type cable in my junk cable
box that I could recover today. Worthwhile project.

73

Bob, K4TAX

On 4/10/2020 12:19 PM, Buck wrote:

> A vendor at Dayton told me *all* are made in China, even the ones
> marked Amphenol.
>
> k4ia, Buck
> K3s# 11497
> Honor Roll 8B DXCC
> EasyWayHamBooks.com
>
> On 4/10/2020 12:43 PM, Irwin Darack wrote:
>> Agreed. Many people buy the cheap ones made in China....and they fail.
>>
>> Irwin KD3TB
>>
>> On Fri, Apr 10, 2020 at 12:28 PM Jim Brown <[hidden email]>
>> wrote:
>>
>>> On 4/10/2020 8:45 AM, Irwin Darack wrote:
>>>> In my experience, coax connectors, barrel connectors, etc. are always
>>> fail
>>>> points when there is a sudden increase in SWR as power is
>>>> increased. They
>>>> oxidize over time and sometimes just reconnecting or replacing is the
>>> first
>>>> step before taking the amp apart.
>>>
>>> If this is happening, I'd suspect 1) the connectors have gotten wet or
>>> 2) the are JUNK connectors. If they aren't labeled "Amphenol," they're
>>> JUNK.
>>>
>>> 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]
>>>
>>
>>
> ______________________________________________________________
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Lyn WØLEN

Re: KPA 500

In reply to this post by Ted Edwards W3TB

Randy –

I’m not the one with issues, it was Alan. I just offered up my experience for his comparison.

73

Lyn, WØLEN

From: Ted Edwards W3TB [mailto:[hidden email]]
Sent: Friday, April 10, 2020 10:32 AM
To: Randy Farmer
Cc: [hidden email]; [hidden email]
Subject: Re: [Elecraft] KPA 500

I am watching this with great interest. If running stations on CW my KPA500 shows low-mid 50sC and I have never known what it should be. Thanks everyone.

On Fri, Apr 10, 2020 at 10:27 Randy Farmer <[hidden email]> wrote:

If the initial VSWR is really measuring 1.00:1 with low power, that
means the detected reflected power is exceptionally low. I'm sure the
algorithm used to compute SWR sets it to 1:1 if there's zero reflected
power. If the load is not really perfectly flat, as the incident power
is increased the detector will finally see enough reflected energy to
give an indication. You have absolutely nothing to worry about in your
system.

73...
Randy, W8FN

On 4/10/2020 9:59 AM, Lyn Norstad wrote:

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--

73 de Ted Edwards, W3TB and GØPWW

and thinking about operating CW:
"Do today what others won't,
so you can do tomorrow what others can't."

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Jim Brown-10

Re: KPA 500

In reply to this post by Buck

On 4/10/2020 10:19 AM, Buck wrote:
> A vendor at Dayton told me *all* are made in China, even the ones marked
> Amphenol.

Um, Apple products have long been made in China. Fair-Rite has had one
or more factories in China for more than a decade. "Made in China" does
NOT define the product as junk. Last I heard, Amphenol is making
connectors in Mexico. Having bought and installed several hundred in the
last decade, the only faults I've found are a few whose screw threads
were short.

And you trust someone working in a trade show booth to know this?
Someone selling junk connectors who disparages a competitor?

73, Jim K9YC

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Lyn WØLEN

Re: KPA 500

In reply to this post by Alan - G4GNX

Many thanks to all who offered me solutions both on and off the list.

But let me clarify ... I wasn't looking for help. My system and my station
are performing very well, and I love it.

I was merely offering up my experience in response to Alan, G4GNX's question
(below).

73
Lyn, WØLEN

-----Original Message-----
From: Lyn Norstad [mailto:[hidden email]]
Sent: Friday, April 10, 2020 8:59 AM
To: 'Alan - G4GNX'; 'Elecraft Reflector'
Subject: RE: [Elecraft] KPA 500

At 100w on 20m, my KAT500 Utility shows an SWR of 1.00 with the KPA500 on
Standby and temp around 38ºC. But as I switch the KPA to Operate and
increase the power to 300w the SWR goes up as high as 1.10. If I hold it
there (key down) long enough the KPA temp starts rising slowly. At about
50ºC I can hear the fan picking up speed. By the time I get to 60ºC the fan
is at probably level 2 or 3. SWR is still at 1.10 (max).
Right or wrong, I've always assumed there is some slight heating in the
antenna system (Tuner, Balun, Lightning protection) although all components
after the tuner are rated at 5 KW.
73
Lyn, WØLEN

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Alan - G4GNX
Sent: Friday, April 10, 2020 6:27 AM
To: Elecraft Reflector
Subject: [Elecraft] KPA 500

I have a strange fault a couple of times recently, where the SWR starts
to increase during the time of a single 'over'. I've been using the K3S
set at 100W out, via the KPA500 (in standby) and the KAT500 tuner,
without any problem, but after I've switched the linear to Operate and
driving it to 200W, the SWR creeps up. I don't think it's an antenna
issue, but a possible heat problem with the KPA500. I watched the
temperature display on the KPA500 and initially on Standby it shows
about 38 degrees C. After transmitting at 200W the temperature slowly
rises above 60 degrees C, but the fan doesn't cut in. Does anyone know
if this is normal behavior and what temperatures I should expect to see?
I have tested the fan via the Menu function and it works as expected.

73,

Alan. G4GNX

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Josh Fiden

Re: KPA 500

In reply to this post by Buck

That’s likely true. But if he’s saying they’re the same as Chinese brand, that’s nonsense.

I use a lot of connectors from Amphenol Audio which are made in China. The difference between Amphenol & equivalent Chinese is obvious on inspection. Mating is very solid and contact plating looks much nicer. Price difference about double. I think the Amphenol connectors are very fairly priced considering the quality differences. I believe the same about their RF connectors.

73
Josh W6XU

Sent from my mobile device

> On Apr 10, 2020, at 10:20 AM, Buck <[hidden email]> wrote:
>
> A vendor at Dayton told me *all* are made in China, even the ones marked Amphenol.

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ANDY DURBIN

KPA 500

In reply to this post by Alan - G4GNX

"After transmitting at 200W the temperature slowly
rises above 60 degrees C, but the fan doesn't cut in. Does anyone know
if this is normal behavior and what temperatures I should expect to see?"

Nominal temperature for start of fan speed 1 is 50 deg C although my data for one test run showed several seconds at 50 deg C and fan not running. It started running just before the temperature rose to 51 deg C.

60 deg C with fan not running is not normal. 60 deg C is the nominal temperature for start of fan speed 3.

73,
Andy, k3wyc

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