Elecraft

KPA500 problem

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Mike Crownover

KPA500 problem

I just bought a lightly used KPA500. It arrived from the seller, well packed
and complete with cables, manuals, etc. I turned the amp on, interfaced it
with my K3, keyed the radio and the KPA500 immediately shut-off. No fault
light or error code, nothing. It shuts down just as if I had pressed the
power button, the fan runs, etc... The antenna is resonant 1:1, I've lowered
input power to 10 watts, swapped coax, hooked it up to another K3, used RCA
to RCA cable, the Elecraft cable, etc.. When down to 10 watts input, I can
tap the paddle like a straight key lightly and the amp works, but put two
dits together and it shuts down.

Has anyone had an experienced anything like this. I keep thinking this has
to be something simple.

Mike AD5A

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Mike Crownover

Re: KPA500 problem

Mark,

Menu is set to K3

I've configured the amp 2 different ways, Key Out to PA Key, with 2
different cables....no difference

KPA500 AUX from K3 to KPA 500, with a known good cable, ( I have a K3 line
already) and the one that came with it....no difference. The band changes
all work fine.

I'm certainly not a technical guy, but it seems to me the transfer from
radio to amp to key the amp is working fine. There is something after key
down that is shorting or somehow malfunctioning that shuts the amp down. I
can turn the power on the K3 down to 10 watts and tap the paddle and the amp
works, but put two dits in a row and it shuts down.

I've inspected the inside for transformer damage and there is nothing
visible. The one lead that Elecraft gave me was that the screws for the tilt
bar were installed backwards, leading to the possibility of a short with the
transformer. I had to remove the transformer to reverse those screws, (they
sent me the procedure), but that wasn't the problem either.

I didn't use a configuration that would require the interrupter.

Thanks for your comments and thoughts.

73,

Mike AD5A

-----Original Message-----
From: Mark E. Musick [mailto:[hidden email]]
Sent: Tuesday, February 16, 2016 1:11 AM
To: 'Mike Crownover' <[hidden email]>
Subject: RE: [Elecraft] KPA500 problem

Mike,
First connect the amp to a dummy load and see how it behaves. This
eliminates the antenna. Yes, I know the SWR is 1:1, but it eliminates it as
a possible problem and you are not putting a signal on the air causing QRM.

Go into the KPA500 menu and make sure RADIO is set to K3.

Are you using the key out of the K3 to the key in (PA KEY) on the amp for
keying the amp or are you keying the amp through the cable connected to the
K3 accessory socket? If you are using key out to key in, did you put the
keying interrupter for pin 11 on the K3 accessory jack?

Try the basic cabling setup as described in the manual.
Just connect RF IN from the K3, RF OUT to the dummy load, KEY OUT on the K3
to PA KEY on the KPA500. Leave the cable from the K3 accessory socket to the
KPA500 AUX socket disconnected. See if it operates in this configuration.

Let us know the results.

Mark Musick, WB9CIF

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Mike
Crownover
Sent: Tuesday, February 16, 2016 4:12 AM
To: [hidden email]
Subject: [Elecraft] KPA500 problem

I just bought a lightly used KPA500. It arrived from the seller, well packed
and complete with cables, manuals, etc. I turned the amp on, interfaced it
with my K3, keyed the radio and the KPA500 immediately shut-off. No fault
light or error code, nothing. It shuts down just as if I had pressed the
power button, the fan runs, etc... The antenna is resonant 1:1, I've lowered
input power to 10 watts, swapped coax, hooked it up to another K3, used RCA
to RCA cable, the Elecraft cable, etc.. When down to 10 watts input, I can
tap the paddle like a straight key lightly and the amp works, but put two
dits together and it shuts down.

Has anyone had an experienced anything like this. I keep thinking this has
to be something simple.

Mike AD5A

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AJ8MH-Radio.Joe.Hutchens

Re: KPA500 problem

No fault codes?

Double check amp's menu items and set all to default before test.

Remove all cables. Connect dummy load directly to amp. Connect RF in
from K3. Connect "Key Out" to "PA Key."

Manually select same band on rig and amp. Set K3 for 10 watts drive.
Select "OPER." Now, try and key amp. You should see asterisk in amp's
display window and around 200 watts out. An asterisk with underscore
indicates amp is being inhibited.

If amp still fails, I would check all connections internal to the amp.
Guess you could also see if the K3 is shutting down...

73,
Joe ( AJ8MH-Radio )

On 2/16/2016 9:33 AM, Mike Crownover wrote:

73,
Joe ( AJ8MH-Radio )

On 2/16/2016 9:33 AM, Mike Crownover wrote:

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Mike Crownover

Re: KPA500 problem

Joe,

I already reset all menu items to default. I've also done the Key Out to PA
Key configuration. I've also done the 10 watt exercise, I am getting the
asterisk without the underscore and the ~200 watts out. But only when I just
tap the paddle. If I string dits together, even at low power the amp shuts
off.

The K3 isn't shutting down.

I sort of in the camp that it's something internal, however, I've never
built one of these. I did get the assembly manual and have looked at some
obvious ground connections and all seem in order.

Thanks for your thoughts.

Mike AD5A

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of AJ8MH
Radio
Sent: Tuesday, February 16, 2016 9:26 AM
To: [hidden email]
Subject: Re: [Elecraft] KPA500 problem

No fault codes?

Double check amp's menu items and set all to default before test.

Remove all cables. Connect dummy load directly to amp. Connect RF in from
K3. Connect "Key Out" to "PA Key."

Manually select same band on rig and amp. Set K3 for 10 watts drive.
Select "OPER." Now, try and key amp. You should see asterisk in amp's
display window and around 200 watts out. An asterisk with underscore
indicates amp is being inhibited.

If amp still fails, I would check all connections internal to the amp.
Guess you could also see if the K3 is shutting down...

73,
Joe ( AJ8MH-Radio )

On 2/16/2016 9:33 AM, Mike Crownover wrote:

73,
Joe ( AJ8MH-Radio )

On 2/16/2016 9:33 AM, Mike Crownover wrote:

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Jack Brindle-2

Re: KPA500 problem

I have to concur, but can’t give any help on what might be shorting. One piece of info I can give - there is no scenario in firmware where a fault will power off the amplifier. All faults will leave the amplifier in the STBY state with the amplifier on. With some you won’t be able to transmit, but the amp will still be powered.

Make sure all connections are right, that no cables are offset or otherwise misconnected. What version of firmware is in the KPA500? If not V1.38 or later, you should upgrade.

Otherwise talk to the CS folks in Watsonville. This is a strange situation. It would be interesting to see the fault table for the amp (you might send me a fault table for analysis). With the amplifier shutting down so quickly I doubt if anything is being saved, though.

Jack Brindle, W6FB
Elecraft Engineering

> On Feb 16, 2016, at 7:39 AM, Mike Crownover <[hidden email]> wrote:
>
> Joe,
>
> I already reset all menu items to default. I've also done the Key Out to PA
> Key configuration. I've also done the 10 watt exercise, I am getting the
> asterisk without the underscore and the ~200 watts out. But only when I just
> tap the paddle. If I string dits together, even at low power the amp shuts
> off.
>
> The K3 isn't shutting down.
>
> I sort of in the camp that it's something internal, however, I've never
> built one of these. I did get the assembly manual and have looked at some
> obvious ground connections and all seem in order.
>
> Thanks for your thoughts.
>
> Mike AD5A
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of AJ8MH
> Radio
> Sent: Tuesday, February 16, 2016 9:26 AM
> To: [hidden email]
> Subject: Re: [Elecraft] KPA500 problem
>
> No fault codes?
>
> Double check amp's menu items and set all to default before test.
>
> Remove all cables. Connect dummy load directly to amp. Connect RF in from
> K3. Connect "Key Out" to "PA Key."
>
> Manually select same band on rig and amp. Set K3 for 10 watts drive.
> Select "OPER." Now, try and key amp. You should see asterisk in amp's
> display window and around 200 watts out. An asterisk with underscore
> indicates amp is being inhibited.
>
> If amp still fails, I would check all connections internal to the amp.
> Guess you could also see if the K3 is shutting down...
>
> 73,
> Joe ( AJ8MH-Radio )
>
> On 2/16/2016 9:33 AM, Mike Crownover wrote:
>
> 73,
> Joe ( AJ8MH-Radio )
>
> On 2/16/2016 9:33 AM, Mike Crownover wrote:
>
> ______________________________________________________________
> Elecraft mailing list
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>
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> Please help support this email list: http://www.qsl.net/donate.html Message
> delivered to [hidden email]
>
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>
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Mike Crownover

Re: KPA500 problem

In reply to this post by Mike Crownover

Did that..."power lost without controlled shutdown"

Thanks,

Mike AD5A

-----Original Message-----
From: Dick Dievendorff [mailto:[hidden email]]
Sent: Tuesday, February 16, 2016 9:53 AM
To: 'Mike Crownover' <[hidden email]>; 'AJ8MH Radio'
<[hidden email]>
Subject: RE: [Elecraft] KPA500 problem

I would recommend connecting the KPA Utility and display the fault table.

73 de Dick, K6KR

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Mike
Crownover
Sent: Tuesday, February 16, 2016 07:39
To: 'AJ8MH Radio' <[hidden email]>
Cc: [hidden email]
Subject: Re: [Elecraft] KPA500 problem

Joe,

I already reset all menu items to default. I've also done the Key Out to PA
Key configuration. I've also done the 10 watt exercise, I am getting the
asterisk without the underscore and the ~200 watts out. But only when I just
tap the paddle. If I string dits together, even at low power the amp shuts
off.

The K3 isn't shutting down.

I sort of in the camp that it's something internal, however, I've never
built one of these. I did get the assembly manual and have looked at some
obvious ground connections and all seem in order.

Thanks for your thoughts.

Mike AD5A

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of AJ8MH
Radio
Sent: Tuesday, February 16, 2016 9:26 AM
To: [hidden email]
Subject: Re: [Elecraft] KPA500 problem

No fault codes?

Double check amp's menu items and set all to default before test.

Remove all cables. Connect dummy load directly to amp. Connect RF in from
K3. Connect "Key Out" to "PA Key."

Manually select same band on rig and amp. Set K3 for 10 watts drive.
Select "OPER." Now, try and key amp. You should see asterisk in amp's
display window and around 200 watts out. An asterisk with underscore
indicates amp is being inhibited.

If amp still fails, I would check all connections internal to the amp.
Guess you could also see if the K3 is shutting down...

73,
Joe ( AJ8MH-Radio )

On 2/16/2016 9:33 AM, Mike Crownover wrote:

73,
Joe ( AJ8MH-Radio )

On 2/16/2016 9:33 AM, Mike Crownover wrote:

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Mike Crownover

Re: KPA500 problem

In reply to this post by Mike Crownover

Bill,

Did that, it's set for 110v. I used the yellow tap, which gives me 75 v,
right in the middle of the spec. I did try the other two, but same behavior.

Thnaks,

Mike AD5A

-----Original Message-----
From: Nr4c [mailto:[hidden email]]
Sent: Tuesday, February 16, 2016 10:19 AM
To: Mike Crownover <[hidden email]>
Subject: Re: [Elecraft] KPA500 problem

What input voltage is it configured for?

Check manual for voltage tap info.

Sent from my iPhone
...nr4c. bill

> On Feb 15, 2016, at 11:11 PM, Mike Crownover <[hidden email]> wrote:
>
> I just bought a lightly used KPA500. It arrived from the seller, well
> packed and complete with cables, manuals, etc. I turned the amp on,
> interfaced it with my K3, keyed the radio and the KPA500 immediately
> shut-off. No fault light or error code, nothing. It shuts down just as
> if I had pressed the power button, the fan runs, etc... The antenna is
> resonant 1:1, I've lowered input power to 10 watts, swapped coax,
> hooked it up to another K3, used RCA to RCA cable, the Elecraft cable,
> etc.. When down to 10 watts input, I can tap the paddle like a
> straight key lightly and the amp works, but put two dits together and it

shuts down.

>
>
>
> Has anyone had an experienced anything like this. I keep thinking this
> has to be something simple.
>
>
>
> Mike AD5A
>
> ______________________________________________________________
> 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]

Cliff Frescura

Re: KPA500 problem

Can you measure the 110V line voltage on key down? Is it stiff enough?

73,

Cliff K3LL/6

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Mike
Crownover
Sent: Tuesday, February 16, 2016 8:22 AM
To: 'Nr4c'
Cc: [hidden email]
Subject: Re: [Elecraft] KPA500 problem

Bill,

Did that, it's set for 110v. I used the yellow tap, which gives me 75 v,
right in the middle of the spec. I did try the other two, but same behavior.

Thnaks,

Mike AD5A

-----Original Message-----
From: Nr4c [mailto:[hidden email]]
Sent: Tuesday, February 16, 2016 10:19 AM
To: Mike Crownover <[hidden email]>
Subject: Re: [Elecraft] KPA500 problem

What input voltage is it configured for?

Check manual for voltage tap info.

Sent from my iPhone
...nr4c. bill

shuts down.

Guy Olinger K2AV

Re: KPA500 problem

Hmm. One of the reasons people get a KPA500 is because they can't get 240
to the shack and the KPA will run on 120V. That makes it non-idiotic to
inquire upon the 120V supply.

I heard of a problem something like this, not a KPA500, that turned out to
be a defective wall outlet. I would imagine that the KPA500 is unforgiving
of a precipitous drop in AC voltage. In the case I cite, all kinds of
wierdness in the shack went away when the wall outlet was replaced. The
defective wall outlet had internal blades that were badly pitted. It was
also very old by any means of estimate.

I also heard of a power cord that was not crimped correctly inside the
molded plug, discovered upon dissection style autopsy afterwards.

Other issues would be aluminum wiring that had not been tightened up, a
single bad socket in a power strip, etc. Also have heard of a wall socket
connection where one of the screws on the outlet had never been tightened.

A KPA500 is a hard pull on a 120V socket. It would not matter to the AC
power that you were just hitting 10 watts, because you turn on the idling
current as soon as any RF is sensed.

Do not assume that the 120V supply is A-OK. Verify everything on that 120V
circuit, up to and including the breaker in the breaker box. Breakers go
bad too.

In any event the very best of luck chasing this aggravating problem. Please
let us all know what finally turns out to be the actual problem and what
you did to fix it.

73, Guy K2AV

On Tue, Feb 16, 2016 at 11:48 AM, Cliff Frescura <[hidden email]> wrote:

> Can you measure the 110V line voltage on key down? Is it stiff enough?
>
> 73,
>
> Cliff K3LL/6
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Mike
> Crownover
> Sent: Tuesday, February 16, 2016 8:22 AM
> To: 'Nr4c'
> Cc: [hidden email]
> Subject: Re: [Elecraft] KPA500 problem
>
> Bill,
>
> Did that, it's set for 110v. I used the yellow tap, which gives me 75 v,
> right in the middle of the spec. I did try the other two, but same
> behavior.
>
> Thnaks,
>
> Mike AD5A
>
> -----Original Message-----
> From: Nr4c [mailto:[hidden email]]
> Sent: Tuesday, February 16, 2016 10:19 AM
> To: Mike Crownover <[hidden email]>
> Subject: Re: [Elecraft] KPA500 problem
>
> What input voltage is it configured for?
>
> Check manual for voltage tap info.
>
> Sent from my iPhone
> ...nr4c. bill
>
>
> > On Feb 15, 2016, at 11:11 PM, Mike Crownover <[hidden email]> wrote:
> >
> > I just bought a lightly used KPA500. It arrived from the seller, well
> > packed and complete with cables, manuals, etc. I turned the amp on,
> > interfaced it with my K3, keyed the radio and the KPA500 immediately
> > shut-off. No fault light or error code, nothing. It shuts down just as
> > if I had pressed the power button, the fan runs, etc... The antenna is
> > resonant 1:1, I've lowered input power to 10 watts, swapped coax,
> > hooked it up to another K3, used RCA to RCA cable, the Elecraft cable,
> > etc.. When down to 10 watts input, I can tap the paddle like a
> > straight key lightly and the amp works, but put two dits together and
> > it
> shuts down.
> >
> >
> >
> > Has anyone had an experienced anything like this. I keep thinking this
> > has to be something simple.
> >
> >
> >
> > Mike AD5A
> >
> > ______________________________________________________________
> > 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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>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message
> delivered to [hidden email]
>
>
>
> ______________________________________________________________
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>

Jim Brown-10

Re: KPA500 problem

On Tue,2/16/2016 10:07 AM, Guy Olinger K2AV wrote:
> I heard of a problem something like this, not a KPA500, that turned out to
> be a defective wall outlet.

Or a long run of relatively small wire to the outlet from the panel. Or
a bad splice at another outlet between your outlet and the breaker
panel. Or perhaps you're not plugged directly into the wall, but into
some other device or multi-outlet box. A good way to check this is to
hang a voltmeter across another outlet wired directly in parallel with
the power amp (most wall outlets are duplexes, two outlets in a single
enclosure) and watch the AC voltage as you key the amp. Start with
fairly low power (100-200W) and gradually increase it until the amp
shuts down. As I recall, the KPA500 pulls about 10A at 120V for full power.

There's a very useful device to measure voltage, current, power, VA,
power factor, and even kWh. It's called Kill A Watt. You plug it into
the outlet, then plug the device you want to test into it. There are
several version of it. Here's one, which is what I have.

http://www.p3international.com/products/p4400.html

73, Jim K9YC

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Mike Crownover

Re: KPA500 problem

In reply to this post by Guy Olinger K2AV

Guy,

I plugged this KPA into the same socket as my current KPA is operating from, so the 120v power source is not the problem. I also swapped power cords with one that was working.

Thanks,

Mike AD5A

> On Feb 16, 2016, at 12:07 PM, Guy Olinger K2AV <[hidden email]> wrote:
>
> Hmm. One of the reasons people get a KPA500 is because they can't get 240 to the shack and the KPA will run on 120V. That makes it non-idiotic to inquire upon the 120V supply.
>
> I heard of a problem something like this, not a KPA500, that turned out to be a defective wall outlet. I would imagine that the KPA500 is unforgiving of a precipitous drop in AC voltage. In the case I cite, all kinds of wierdness in the shack went away when the wall outlet was replaced. The defective wall outlet had internal blades that were badly pitted. It was also very old by any means of estimate.
>
> I also heard of a power cord that was not crimped correctly inside the molded plug, discovered upon dissection style autopsy afterwards.
>
> Other issues would be aluminum wiring that had not been tightened up, a single bad socket in a power strip, etc. Also have heard of a wall socket connection where one of the screws on the outlet had never been tightened.
>
> A KPA500 is a hard pull on a 120V socket. It would not matter to the AC power that you were just hitting 10 watts, because you turn on the idling current as soon as any RF is sensed.
>
> Do not assume that the 120V supply is A-OK. Verify everything on that 120V circuit, up to and including the breaker in the breaker box. Breakers go bad too.
>
> In any event the very best of luck chasing this aggravating problem. Please let us all know what finally turns out to be the actual problem and what you did to fix it.
>
> 73, Guy K2AV
>
>> On Tue, Feb 16, 2016 at 11:48 AM, Cliff Frescura <[hidden email]> wrote:
>> Can you measure the 110V line voltage on key down? Is it stiff enough?
>>
>> 73,
>>
>> Cliff K3LL/6
>>
>> -----Original Message-----
>> From: Elecraft [mailto:[hidden email]] On Behalf Of Mike
>> Crownover
>> Sent: Tuesday, February 16, 2016 8:22 AM
>> To: 'Nr4c'
>> Cc: [hidden email]
>> Subject: Re: [Elecraft] KPA500 problem
>>
>> Bill,
>>
>> Did that, it's set for 110v. I used the yellow tap, which gives me 75 v,
>> right in the middle of the spec. I did try the other two, but same behavior.
>>
>> Thnaks,
>>
>> Mike AD5A
>>
>> -----Original Message-----
>> From: Nr4c [mailto:[hidden email]]
>> Sent: Tuesday, February 16, 2016 10:19 AM
>> To: Mike Crownover <[hidden email]>
>> Subject: Re: [Elecraft] KPA500 problem
>>
>> What input voltage is it configured for?
>>
>> Check manual for voltage tap info.
>>
>> Sent from my iPhone
>> ...nr4c. bill
>>
>>
>> > On Feb 15, 2016, at 11:11 PM, Mike Crownover <[hidden email]> wrote:
>> >
>> > I just bought a lightly used KPA500. It arrived from the seller, well
>> > packed and complete with cables, manuals, etc. I turned the amp on,
>> > interfaced it with my K3, keyed the radio and the KPA500 immediately
>> > shut-off. No fault light or error code, nothing. It shuts down just as
>> > if I had pressed the power button, the fan runs, etc... The antenna is
>> > resonant 1:1, I've lowered input power to 10 watts, swapped coax,
>> > hooked it up to another K3, used RCA to RCA cable, the Elecraft cable,
>> > etc.. When down to 10 watts input, I can tap the paddle like a
>> > straight key lightly and the amp works, but put two dits together and
>> > it
>> shuts down.
>> >
>> >
>> >
>> > Has anyone had an experienced anything like this. I keep thinking this
>> > has to be something simple.
>> >
>> >
>> >
>> > Mike AD5A
>> >
>> > ______________________________________________________________
>> > 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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>> 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]
>

Jim Bolit

Re: KPA500 problem

In reply to this post by Guy Olinger K2AV

The load regulation of the transformer/rectifiers is also an issue.

Does Elecraft spec the load regulation of the KPA-500 at nominal AC input
for both 110 and 220 volt input?

Jim
W6AIM

.

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Ron
D'Eau Claire
Sent: Tuesday, February 16, 2016 3:41 PM
To: 'Elecraft Reflector'
Subject: Re: [Elecraft] KPA500 problem

On the fairly rare occasions I go QRO with the KPA500 it runs off of a 120V
wall outlet >50 feet from the breaker panel.

With the taps set so the key-up HV is near max (85V), the HV drops to close
to the minimum voltage (60V) at 500 watts on some bands. That's all due to
the 120V feed droop. There's no benefit from having the tap set for a
mid-range voltage if the HV droops below 60V on key down. Below 60V the amp
won't make full output on some bands and IMD is compromised. A
self-protective circuit will kick in and shut the power supply off if the
key-up voltage is too high. In that case you will get an immediate fault
indication when you press the ON switch to apply power.

It is useful to not have other heavy loads on the same circuit - especially
loads that switch on and off (Microwave oven, household vacuum cleaner,
etc.) Even if such loads do not cause the circuit breaker to open, they can
cause the voltage at your outlet to shift even further.

73, Ron AC7AC

-----Original Message-----

> > On Feb 15, 2016, at 11:11 PM, Mike Crownover <[hidden email]> wrote:
> >
> > I just bought a lightly used KPA500. It arrived from the seller,
> > well packed and complete with cables, manuals, etc. I turned the amp
> > on, interfaced it with my K3, keyed the radio and the KPA500
> > immediately shut-off. No fault light or error code, nothing. It
> > shuts down just as if I had pressed the power button, the fan runs,
> > etc... The antenna is resonant 1:1, I've lowered input power to 10
> > watts, swapped coax, hooked it up to another K3, used RCA to RCA
> > cable, the Elecraft cable, etc.. When down to 10 watts input, I can
> > tap the paddle like a straight key lightly and the amp works, but
> > put two dits together and it
> shuts down.
> >
> >
> >
> > Has anyone had an experienced anything like this. I keep thinking
> > this has to be something simple.
> >
> >
> >
> > Mike AD5A

Jim Bolit

Re: KPA500 problem

Their methods show BOTH line regulation and load regulation.

How much does the voltage change with a stiff, low impedance line or an
electronic AC generator that will keep the line at 110 or 220, regardless of
load(within limits of course)?

I get a sense the transformer is not that robust, but have no facts to back
that statement.

Jim
W6AIM

.

-----Original Message-----
From: Ron D'Eau Claire [mailto:[hidden email]]
Sent: Tuesday, February 16, 2016 5:13 PM
To: 'Jim Bolit'; 'Elecraft Reflector'
Subject: RE: [Elecraft] KPA500 problem

I've not seen any such specs., but since the measurements for setting the
taps and checking the regulation (load/no-load voltages) are done using the
actual HV at the output of the power supply, as long as it stays within the
stated range it should work FB.

73, Ron AC7AC

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Jim
Bolit
Sent: Tuesday, February 16, 2016 4:01 PM
To: 'Ron D'Eau Claire'; 'Elecraft Reflector'
Subject: Re: [Elecraft] KPA500 problem

The load regulation of the transformer/rectifiers is also an issue.

Does Elecraft spec the load regulation of the KPA-500 at nominal AC input
for both 110 and 220 volt input?

Jim
W6AIM

.

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Ron
D'Eau Claire
Sent: Tuesday, February 16, 2016 3:41 PM
To: 'Elecraft Reflector'
Subject: Re: [Elecraft] KPA500 problem

On the fairly rare occasions I go QRO with the KPA500 it runs off of a 120V
wall outlet >50 feet from the breaker panel.

With the taps set so the key-up HV is near max (85V), the HV drops to close
to the minimum voltage (60V) at 500 watts on some bands. That's all due to
the 120V feed droop. There's no benefit from having the tap set for a
mid-range voltage if the HV droops below 60V on key down. Below 60V the amp
won't make full output on some bands and IMD is compromised. A
self-protective circuit will kick in and shut the power supply off if the
key-up voltage is too high. In that case you will get an immediate fault
indication when you press the ON switch to apply power.

It is useful to not have other heavy loads on the same circuit - especially
loads that switch on and off (Microwave oven, household vacuum cleaner,
etc.) Even if such loads do not cause the circuit breaker to open, they can
cause the voltage at your outlet to shift even further.

73, Ron AC7AC

-----Original Message-----

______________________________________________________________
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]

______________________________________________________________
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]

Don Wilhelm-4

Re: KPA500 problem

Jim,

I think you will find the KPA500 transformer to be quite robust, but of
course there is always a small chance that you have one that could be
defective. If you can monitor the DC voltage under load, that would be
revealing.
Contact [hidden email] or Jack Brindle (he has already responded
to you and is one of the KPA500 designers).

73,
Don W3FPR

On 2/16/2016 11:26 PM, Jim Bolit wrote:

> Their methods show BOTH line regulation and load regulation.
>
> How much does the voltage change with a stiff, low impedance line or an
> electronic AC generator that will keep the line at 110 or 220, regardless of
> load(within limits of course)?
>
> I get a sense the transformer is not that robust, but have no facts to back
> that statement.
>
>

Dan Maase AC6DM

Re: KPA500 problem

In reply to this post by Mike Crownover

Mike:
Suggest changing fuses in input fuse block. I have experienced an intermittent fuse problem in other equipment in the past that produced very puzzling symptoms.
73 and good luck,
Dan
AC6DM