Elecraft

KPA3 failure?

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Pete Smith N4ZR

KPA3 failure?

My K3/100 #4275 has suddenly stopped making 100 watts, and is now making
10-20 on 160-20 meters, and 45-50 on 17-10 meters , even though the
power control says it should be making 99 watts. On the way to its
current state, it cycled once through reduced power and back to full
power after a band change, so I suspect something was in the process of
failing. Any ideas where to start troubleshooting, or is this something
that warrants a trip back to the mother ship?

Addendum: In further testing, with power turned below 10 watts to
disable the KPA3, I'm now seeing less than 1 watt on 160, 8 on 80, 8 on
40 and 11-13 on 20-10. Turning the power back up to 100 watts, I now
have 20 watts on 160, 35 on 80, 25 on 40, 50 on 20, 85 on 15 and 100 on 10m.

Should I first try recalibrating the TX gain?
--

73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.

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Don Wilhelm-4

Re: KPA3 failure?

Pete,

Usually the first thing the folks at support will ask you to do is to
run the TX Gain Calibration, so yes, that is the first thing you should try.

73,
Don W3FPR

On 2/5/2015 8:05 AM, Pete Smith N4ZR wrote:

> My K3/100 #4275 has suddenly stopped making 100 watts, and is now
> making 10-20 on 160-20 meters, and 45-50 on 17-10 meters , even though
> the power control says it should be making 99 watts. On the way to
> its current state, it cycled once through reduced power and back to
> full power after a band change, so I suspect something was in the
> process of failing. Any ideas where to start troubleshooting, or is
> this something that warrants a trip back to the mother ship?
>
> Addendum: In further testing, with power turned below 10 watts to
> disable the KPA3, I'm now seeing less than 1 watt on 160, 8 on 80, 8
> on 40 and 11-13 on 20-10. Turning the power back up to 100 watts, I
> now have 20 watts on 160, 35 on 80, 25 on 40, 50 on 20, 85 on 15 and
> 100 on 10m.
>
> Should I first try recalibrating the TX gain?

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Elecraft mailing list

Re: KPA3 failure?

In reply to this post by Pete Smith N4ZR

I would start with doing the 'Calibrate Transmitter Gain'

From: Pete Smith N4ZR <[hidden email]>
To: Elecraft List <[hidden email]>
Sent: Thursday, February 5, 2015 8:05 AM
Subject: [Elecraft] KPA3 failure?

My K3/100 #4275 has suddenly stopped making 100 watts, and is now making
10-20 on 160-20 meters, and 45-50 on 17-10 meters , even though the
power control says it should be making 99 watts. On the way to its
current state, it cycled once through reduced power and back to full
power after a band change, so I suspect something was in the process of
failing. Any ideas where to start troubleshooting, or is this something
that warrants a trip back to the mother ship?

Addendum: In further testing, with power turned below 10 watts to
disable the KPA3, I'm now seeing less than 1 watt on 160, 8 on 80, 8 on
40 and 11-13 on 20-10. Turning the power back up to 100 watts, I now
have 20 watts on 160, 35 on 80, 25 on 40, 50 on 20, 85 on 15 and 100 on 10m.

Should I first try recalibrating the TX gain?
--

73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.

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Help: http://mailman.qth.net/mmfaq.htm
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Joe Subich, W4TV-4

Re: KPA3 failure?

In reply to this post by Pete Smith N4ZR

Pete,

Sounds like a low power amplifier failure. Call Elecraft Support to
discuss but I suspect they can send you a board to swap.

73,

... Joe, W4TV

On 2015-02-05 8:05 AM, Pete Smith N4ZR wrote:

> My K3/100 #4275 has suddenly stopped making 100 watts, and is now making
> 10-20 on 160-20 meters, and 45-50 on 17-10 meters , even though the
> power control says it should be making 99 watts. On the way to its
> current state, it cycled once through reduced power and back to full
> power after a band change, so I suspect something was in the process of
> failing. Any ideas where to start troubleshooting, or is this something
> that warrants a trip back to the mother ship?
>
> Addendum: In further testing, with power turned below 10 watts to
> disable the KPA3, I'm now seeing less than 1 watt on 160, 8 on 80, 8 on
> 40 and 11-13 on 20-10. Turning the power back up to 100 watts, I now
> have 20 watts on 160, 35 on 80, 25 on 40, 50 on 20, 85 on 15 and 100 on
> 10m.
>
> Should I first try recalibrating the TX gain?