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Strange Amplifier behavior

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Strange Amplifier behavior

I have a relatively old K3, which I use together with a KPA500 and a KAT500. Most of the time this works flawlessly.

However, occasionally the K3 gets confused and doesn’t realize that the KPA500 is in “Operate” mode (rather an in standby). This results in the K3 sending 100 watts to the amp, and the amp faults.

Again, this doesn’t happen often, and I can’t ascertain why it occurs. Most of the time all is OK.

The K3, KPA500 and the KAT500 all are running the latest firmware.

Any idea?

73

Tom W4KX
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k6dgw

Re: Strange Amplifier behavior

I can't answer your question but when I still had my KPA500, I had that
same issue. Got in the habit of always checking the power setting
before keying when I put the amp into OPR.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 7/5/2020 2:07 PM, Tom Doligalski via Elecraft wrote:

> I have a relatively old K3, which I use together with a KPA500 and a KAT500. Most of the time this works flawlessly.
>
> However, occasionally the K3 gets confused and doesn’t realize that the KPA500 is in “Operate” mode (rather an in standby). This results in the K3 sending 100 watts to the amp, and the amp faults.
>
> Again, this doesn’t happen often, and I can’t ascertain why it occurs. Most of the time all is OK.
>
> The K3, KPA500 and the KAT500 all are running the latest firmware.
>
> Any idea?
>
> 73
>
> Tom W4KX
>

Elecraft mailing list

Re: Strange Amplifier behavior

Interesting!

This has begun just in the last few weeks.

Thx!

Tom W4KX

Sent from my iPad

> On Jul 5, 2020, at 5:37 PM, Fred Jensen <[hidden email]> wrote:
>
> I can't answer your question but when I still had my KPA500, I had that same issue. Got in the habit of always checking the power setting before keying when I put the amp into OPR.
>
> 73,
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
>> On 7/5/2020 2:07 PM, Tom Doligalski via Elecraft wrote:
>> I have a relatively old K3, which I use together with a KPA500 and a KAT500. Most of the time this works flawlessly.
>>
>> However, occasionally the K3 gets confused and doesn’t realize that the KPA500 is in “Operate” mode (rather an in standby). This results in the K3 sending 100 watts to the amp, and the amp faults.
>>
>> Again, this doesn’t happen often, and I can’t ascertain why it occurs. Most of the time all is OK.
>>
>> The K3, KPA500 and the KAT500 all are running the latest firmware.
>>
>> Any idea?
>>
>> 73
>>
>> Tom W4KX
>>
>
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k6dgw

Re: Strange Amplifier behavior

Mine was so intermittent that I could never reconstruct the actions I
had taken prior to seeing the anomaly ... often a month or more would go
by. I had the control cables between K3, KPA500, and KAT500 connected,
and in every other way, the three components played together
flawlessly. It was discussed here back when the KPA500 first came out
and the K3 FW had been changed to include the feature. I don't recall
that there was ever a diagnosis or resolution.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 7/5/2020 2:54 PM, Tom Doligalski wrote:
> Interesting!
>
> This has begun just in the last few weeks.
>
> Thx!
>
> Tom W4KX
>
>

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Elecraft mailing list

Re: Strange Amplifier behavior

In reply to this post by Elecraft mailing list

I have seen this happen when the K3 was connected to a computer via either USB or an RS232 serial cable and the computer was polling the K3 at a rapid rate (like several times a second) to determine its’ frequency and/or other operating parameters. This can cause the K3 to miss the data line signal from the KPA500. My solution was to slow the polling rate of the PC software.

73, Charles, K4ZRJ

> On Jul 5, 2020, at 17:07, Tom Doligalski via Elecraft <[hidden email]> wrote:
>
> I have a relatively old K3, which I use together with a KPA500 and a KAT500. Most of the time this works flawlessly.
>
> However, occasionally the K3 gets confused and doesn’t realize that the KPA500 is in “Operate” mode (rather an in standby). This results in the K3 sending 100 watts to the amp, and the amp faults.
>
> Again, this doesn’t happen often, and I can’t ascertain why it occurs. Most of the time all is OK.
>
> The K3, KPA500 and the KAT500 all are running the latest firmware.
>
> Any idea?
>
> 73
>
> Tom W4KX
> ______________________________________________________________
> 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
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k6mrmagnet

Re: Strange Amplifier behavior

In reply to this post by Elecraft mailing list

The only way the K3 knows that the KPA500 is in operate is via an AuxBus message. So if it misses it for some reason, it won’t switch. Be sure the cable between the radio Aux port and the amp is completely seated and such. And make it a habit to watch the front panel on the K3 when you switch on the KPA or select operate. You should see the KPA500 Operate message. The other way you can check is wiggle the PWR knob and make sure the * is in the window. That tells you that the radio is using the amp power settings.

Ken K6MR

From: Tom Doligalski via Elecraft<mailto:[hidden email]>
Sent: Sunday, July 5, 2020 14:55
To: Fred Jensen<mailto:[hidden email]>
Cc: [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] Strange Amplifier behavior

Interesting!

This has begun just in the last few weeks.

Thx!

Tom W4KX

Sent from my iPad

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Elecraft mailing list

Re: Strange Amplifier behavior

In reply to this post by Elecraft mailing list

I have the USB communicating at 38400 Will try and back that off and see if that helps!

Tom W4KX

From: Charles Johnson
Sent: Sunday, July 5, 2020 6:29 PM
To: Tom Doligalski
Cc: Elecraft Reflector
Subject: Re: [Elecraft] Strange Amplifier behavior

I have seen this happen when the K3 was connected to a computer via either USB or an RS232 serial cable and the computer was polling the K3 at a rapid rate (like several times a second) to determine its’ frequency and/or other operating parameters. This can cause the K3 to miss the data line signal from the KPA500. My solution was to slow the polling rate of the PC software.

73, Charles, K4ZRJ

KENT TRIMBLE

Re: Strange Amplifier behavior

In reply to this post by k6mrmagnet

True, unless you have the KPA500 configured (as I do) to be in Standby Mode upon power-up.

73,

Kent K9ZTV

> On Jul 5, 2020, at 5:31 PM, Ken K6MR <[hidden email]> wrote:
>
> ... when you switch on the KPA500... you should see the KPA500 Operate message.

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ANDY DURBIN

Strange Amplifier behavior

In reply to this post by Elecraft mailing list

"I have the USB communicating at 38400 Will try and back that off and see if that helps!"

You seem to have confused "polling rate" with "Baud rate". Polling rate defines the interval between each frame of data requests (how frequently each request is sent). Baud defines how quickly each of those data requests is sent (the time it takes for each request to be transmitted).

To reduce the K3 processor workload you would need to reduce the polling rate, not the Baud rate.

I cannot comment on whether either will impact your problem.

Andy, k3wyc

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