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K3S Power Issue

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Serge_VA3SB

K3S Power Issue

Hello to the group. I am a new user of the K3S/KAT500 combo.
Had fun using the rig during the contest over the weekend. I had it set for 100 watts and it worked very well.
However, today I thought that i would place the KAT500 underneath the K3S. So after moving the KAT under the K3S I reconnected the cables and power to both units.

No changes were made to any of the antennas and my swr on all antennas 80-10M is approx 1.1/1.2 - 1.
I cannot seem to be able to get the output power to 100 W. I adjusted the power control for 100 W but when I transmit I can only get between 75-80 Watts output maximum.

Did I happen to hit a button accidentally when moving the equipment?

Any assistance would be greatly appreciated. Thanks in advance.

Regards

Serge
VA3SB

Don Wilhelm

Re: K3S Power Issue

Serge,

The first thing to do with a power output anomaly is to connect a dummy
load good for at least 100 watts and 50 ohms non-reactive to the K3 and
run the TX Gain Calibration from K3 Utility.

The next thing to do is to check all connectors to make sure they are
tight. With PL-259s, 'finger-tight' may not be tight enough to insure
good contact for the shield connection - use pliers and give them that
LITTLE bit of extra tightness - don't overdo it.

I certainly cannot guess at what might have changed, but TX Gain
Calibration is a good place to start.

After that, since your antennas have a low SWR, you might try it with
the KAT500 in bypass.

On 3/27/2017 4:27 PM, Serge_VA3SB wrote:

> Hello to the group. I am a new user of the K3S/KAT500 combo.
> Had fun using the rig during the contest over the weekend. I had it set for
> 100 watts and it worked very well.
> However, today I thought that i would place the KAT500 underneath the K3S.
> So after moving the KAT under the K3S I reconnected the cables and power to
> both units.
>
> No changes were made to any of the antennas and my swr on all antennas
> 80-10M is approx 1.1/1.2 - 1.
> I cannot seem to be able to get the output power to 100 W.

Serge_VA3SB

Re: K3S Power Issue

Thank you very much for your prompt response Don.

I have conducted a couple of additional tests and with an external power meter, even though the K3S indicates a power output of 75-80W, my external meter shows a power output of 100W.

I will tighten all of the connections and my try some other cables as I only have the equipment connected on my desktop in the interim.

Thanks again for your assistance.

Serge

VA3SB

---------- Original Message ----------
From: "Don Wilhelm [via Elecraft]" <[hidden email]>
Date: March 27, 2017 at 4:57 PM

Serge,

The first thing to do with a power output anomaly is to connect a dummy
load good for at least 100 watts and 50 ohms non-reactive to the K3 and
run the TX Gain Calibration from K3 Utility.

The next thing to do is to check all connectors to make sure they are
tight. With PL-259s, 'finger-tight' may not be tight enough to insure
good contact for the shield connection - use pliers and give them that
LITTLE bit of extra tightness - don't overdo it.

I certainly cannot guess at what might have changed, but TX Gain
Calibration is a good place to start.

After that, since your antennas have a low SWR, you might try it with
the KAT500 in bypass.

On 3/27/2017 4:27 PM, Serge_VA3SB wrote:

> Hello to the group. I am a new user of the K3S/KAT500 combo.
> Had fun using the rig during the contest over the weekend. I had it set for
> 100 watts and it worked very well.
> However, today I thought that i would place the KAT500 underneath the K3S.
> So after moving the KAT under the K3S I reconnected the cables and power to
> both units.
>
> No changes were made to any of the antennas and my swr on all antennas
> 80-10M is approx 1.1/1.2 - 1.
> I cannot seem to be able to get the output power to 100 W.
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Edward R Cole

Re: K3S Power Issue

In reply to this post by Serge_VA3SB

Normally, I do not respond to most of these issues; Don is an expert
and gives great advice.

What you last wrote shows that you NEED to do a TX Gain
Calibration. Your external power meter shows full output, so the K3s
meter ckts need to be re-calibrated to agree with the ext. meter
reading (assuming you trust the external meter).

Be sure that you use a 50-ohm non-reactive load (translation: a good
dummy load). If you measure into an antenna with any SWR > 1.05 the
output power will not read accurately. Power meters (SWR meters) are
actually RF voltmeters and require a "perfect" 50-ohms to read correctly.

GL sounds like you are close to "fixing" your issues.

73, Ed - KL7UW

Date: Mon, 27 Mar 2017 14:17:24 -0700 (MST)
From: Serge_VA3SB <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] K3S Power Issue

Thank you very much for your prompt response Don. 
I have conducted a couple of additional tests and with an external
power meter, even though the K3S indicates a power output of 75-80W,
my external meter shows a power output of 100W. 
I will tighten all of the connections and my try some other cables
as I only have the equipment connected on my desktop in the interim. 
Thanks again for your assistance.
73
Serge
VA3SB

73, Ed - KL7UW
http://www.kl7uw.com
Dubus-NA Business mail:
[hidden email]

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Elecraft mailing list

Re: K3S Power Issue

I second that recommendation, It's a nice dummy load.

From: Walter Underwood <[hidden email]>
To: Elecraft Reflector <[hidden email]>
Sent: Monday, March 27, 2017 9:40 PM
Subject: Re: [Elecraft] K3S Power Issue

If you don’t have a 100 W dummy load, I recommend this one. For $40 and an hour or so of soldering, you’ll have one. I built this just before assembling my KXPA100.

http://www.ohr.com/rfl100.htm <http://www.ohr.com/rfl100.htm>

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

> On Mar 27, 2017, at 5:39 PM, Edward R Cole <[hidden email]> wrote:
>
> Normally, I do not respond to most of these issues; Don is an expert and gives great advice.
>
> What you last wrote shows that you NEED to do a TX Gain Calibration. Your external power meter shows full output, so the K3s meter ckts need to be re-calibrated to agree with the ext. meter reading (assuming you trust the external meter).
>
> Be sure that you use a 50-ohm non-reactive load (translation: a good dummy load). If you measure into an antenna with any SWR > 1.05 the output power will not read accurately. Power meters (SWR meters) are actually RF voltmeters and require a "perfect" 50-ohms to read correctly.
>
> GL sounds like you are close to "fixing" your issues.
>
> 73, Ed - KL7UW
>
> Date: Mon, 27 Mar 2017 14:17:24 -0700 (MST)
> From: Serge_VA3SB <[hidden email]>
> To: [hidden email]
> Subject: Re: [Elecraft] K3S Power Issue
>
> Thank you very much for your prompt response Don.
> I have conducted a couple of additional tests and with an external power meter, even though the K3S indicates a power output of 75-80W, my external meter shows a power output of 100W.
> I will tighten all of the connections and my try some other cables as I only have the equipment connected on my desktop in the interim.
> Thanks again for your assistance.
> 73
> Serge
> VA3SB
>
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> Dubus-NA Business mail:
> [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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