Elecraft

80 meters

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Mal Speer

80 meters

I seem to have low output on 75 phone. The most power I can put out is 71
watts. I can turn the power knob to 100 watts, but it backs down to 71
immediately. This is into an antenna and a dummy load.

I just checked 160 same thing except I get 83 watts

All other bands seem OK

Mal WA2TWA

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Mal Speer

Re: 80 meters

I forgot to say that the rig is a factory built K3s
Mal

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Mal Speer
Sent: Saturday, December 30, 2017 9:52 PM
To: [hidden email]
Subject: [Elecraft] 80 meters

I seem to have low output on 75 phone. The most power I can put out is 71
watts. I can turn the power knob to 100 watts, but it backs down to 71
immediately. This is into an antenna and a dummy load.

I just checked 160 same thing except I get 83 watts

All other bands seem OK

Mal WA2TWA

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Re: 80 meters

Make sure your power supply provides enough voltage and can handle the power draw (300 watts is probably a good number). This happened to me too when I accidentally adjusted the voltage of my PSU too low. I now have it at 13.6V.

Sent from Mail for Windows 10

From: Mal Speer
Sent: Saturday, December 30, 2017 8:01 PM
To: 'Mal Speer'; [hidden email]
Subject: Re: [Elecraft] 80 meters

I forgot to say that the rig is a factory built K3s
Mal

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Mal Speer
Sent: Saturday, December 30, 2017 9:52 PM
To: [hidden email]
Subject: [Elecraft] 80 meters

I seem to have low output on 75 phone. The most power I can put out is 71
watts. I can turn the power knob to 100 watts, but it backs down to 71
immediately. This is into an antenna and a dummy load.

I just checked 160 same thing except I get 83 watts

All other bands seem OK

Mal WA2TWA

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Brian Hunt

Re: 80 meters

In reply to this post by Mal Speer

I had a similar problem on the low bands. I did three things: 1- Replaced the stock power cord with ~4 ft of #10 twisted pair cable; 2- Turned up the no-load voltage on the Actron linear supply to 14.2 v which gives me better than 13.5v @ 100w key down on the K3 display and 3- reran the K3 Power Cal procedure with the K3 Utility. It's been fine ever since. GL+HNY

73,
Brian, K0DTJ

> On Dec 30, 2017, at 18:51, Mal Speer <[hidden email]> wrote:
>
> I seem to have low output on 75 phone. The most power I can put out is 71
> watts. I can turn the power knob to 100 watts, but it backs down to 71
> immediately. This is into an antenna and a dummy load.
>

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Bob McGraw - K4TAX

Re: 80 meters

In reply to this post by Mal Speer

I run my power supply at 14.0 volts as measured at the supply. This is
done to accommodate the ~0.25 - ~0.35 volt drop in the DC line between
the supply and the radio when in transmit.

73

Bob, K4TAX

On 12/30/2017 10:20 PM, Barthold Lichtenbelt via Elecraft wrote:

> Make sure your power supply provides enough voltage and can handle the power draw (300 watts is probably a good number). This happened to me too when I accidentally adjusted the voltage of my PSU too low. I now have it at 13.6V.
>
> Sent from Mail for Windows 10
>
> From: Mal Speer
> Sent: Saturday, December 30, 2017 8:01 PM
> To: 'Mal Speer'; [hidden email]
> Subject: Re: [Elecraft] 80 meters
>
> I forgot to say that the rig is a factory built K3s
> Mal
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Mal Speer
> Sent: Saturday, December 30, 2017 9:52 PM
> To: [hidden email]
> Subject: [Elecraft] 80 meters
>
> I seem to have low output on 75 phone. The most power I can put out is 71
> watts. I can turn the power knob to 100 watts, but it backs down to 71
> immediately. This is into an antenna and a dummy load.
>
> I just checked 160 same thing except I get 83 watts
>
> All other bands seem OK
>
> Mal WA2TWA
>
>
>
>
>
> ______________________________________________________________
> 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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> Post: mailto:[hidden email]
>
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>
> ______________________________________________________________
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>
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>

donovanf

Re: 80 meters

Hi Bob,

Rather than estimating the loss in your power cord, your K3 has the
capability to accurately measure and display the DC power voltage
internal to your transceiver.

Tap DISPLAY and rotate the VFO B dial to show the K3 power
supply voltage when you're transmitting.

73
Frank
W3LPL

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

From: "Bob McGraw K4TAX" <[hidden email]>
To: [hidden email]
Sent: Sunday, December 31, 2017 2:27:01 PM
Subject: Re: [Elecraft] 80 meters

I run my power supply at 14.0 volts as measured at the supply. This is
done to accommodate the ~0.25 - ~0.35 volt drop in the DC line between
the supply and the radio when in transmit.

73

Bob, K4TAX

On 12/30/2017 10:20 PM, Barthold Lichtenbelt via Elecraft wrote:

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Bob McGraw - K4TAX

Re: 80 meters

Yes, I've done that. However, since the radio draws a different amount
of current at 100 watts CW into a 50 ohm dummy load depending on band,
the IR drop in the DC line will be slightly different from band to band.

73

Bob, K4TAX

On 12/31/2017 10:18 AM, [hidden email] wrote:

> Hi Bob,
>
> Rather than estimating the loss in your power cord, your K3 has the
> capability to accurately measure and display the DC power voltage
> internal to your transceiver.
>
> Tap DISPLAY and rotate the VFO B dial to show the K3 power
> supply voltage when you're transmitting.
>
> 73
> Frank
> W3LPL
>
> ------------------------------------------------------------------------
> *From: *"Bob McGraw K4TAX" <[hidden email]>
> *To: *[hidden email]
> *Sent: *Sunday, December 31, 2017 2:27:01 PM
> *Subject: *Re: [Elecraft] 80 meters
>
> I run my power supply at 14.0 volts as measured at the supply. This is
> done to accommodate the ~0.25 - ~0.35 volt drop in the DC line between
> the supply and the radio when in transmit.
>
> 73
>
> Bob, K4TAX
>
>
> On 12/30/2017 10:20 PM, Barthold Lichtenbelt via Elecraft wrote:
> > Make sure your power supply provides enough voltage and can handle
> the power draw (300 watts is probably a good number). This happened to
> me too when I accidentally adjusted the voltage of my PSU too low. I
> now have it at 13.6V.
> >
> > Sent from Mail for Windows 10
> >
> > From: Mal Speer
> > Sent: Saturday, December 30, 2017 8:01 PM
> > To: 'Mal Speer'; [hidden email]
> > Subject: Re: [Elecraft] 80 meters
> >
> > I forgot to say that the rig is a factory built K3s
> > Mal
> >
> > -----Original Message-----
> > From: [hidden email]
> > [mailto:[hidden email]] On Behalf Of Mal Speer
> > Sent: Saturday, December 30, 2017 9:52 PM
> > To: [hidden email]
> > Subject: [Elecraft] 80 meters
> >
> > I seem to have low output on 75 phone. The most power I can put out
> is 71
> > watts. I can turn the power knob to 100 watts, but it backs down to 71
> > immediately. This is into an antenna and a dummy load.
> >
> > I just checked 160 same thing except I get 83 watts
> >
> > All other bands seem OK
> >
> > Mal WA2TWA
> >
> >
> >
> >
> >
> > ______________________________________________________________
> > 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]
> >
>
>
> ______________________________________________________________
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>

Jim Brown-10

Re: 80 meters

On 12/31/2017 10:42 AM, Bob McGraw K4TAX wrote:
> Yes, I've done that. However, since the radio draws a different
> amount of current at 100 watts CW into a 50 ohm dummy load depending
> on band, the IR drop in the DC line will be slightly different from
> band to band.

Most rigs that run on DC are designed to be run at 13.8V. It's important
to realize that IMD in many rigs, including the K3, increases with power
output AND with reduced power supply voltage. K6XX is an EE at Elecraft
who works in manufacturing -- that is, taking designs from the team,
putting them into production, and preliminary testing for the FCC
approval process. Bob, a serious contester, is my neighbor, and we are
both members of the Northern California Contest Club (as is Eric Swartz).

Several years ago, Bob put together a technical talk for NCCC on IMD, to
which I contributed some on-air measurements and observations on the
contributions of audio to distortion and splatter. Bob's slides include
lab measurements documenting the increased IMD resulting from operating
at reduced power supply voltage and closer to rated output. BTW -- early
K3 firmware permitted operation to 120W; that was reduced to 110W
because IMD at the higher power level was judged excessive. The slides
for that talk are at

http://k9yc.com/K6XXAmpTalk.pdf

I've since done my own measurements showing that CW bandwidth is
considerably lower at the 30-60W levels needed to drive most power amps
than at 100W. That data is at

http://k9yc.com/P3_Spectrum_Measurements.pdf

In my own shack, a pair of K3s (for SO2R) runs from a 100Ah
float-charged LiFePO battery, so terminal voltage stays in the range of
13-13.6V keydown. About two years ago, I switched to the LiFePO battery
from a big lead acid battery, because terminal voltage under load was in
the range of 12.3 - 11.8V.

73, Jim K9YC

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Elecraft mailing list

Re: 80 meters

In reply to this post by Brian Hunt

➢ and 3- reran the K3 Power Cal procedure with the K3 Utility.

Yes, great advice. Definitely do this.

73,
Barthold

From: Brian Hunt
Sent: Saturday, December 30, 2017 9:49 PM
To: [hidden email]
Subject: Re: [Elecraft] 80 meters

I had a similar problem on the low bands. I did three things: 1- Replaced the stock power cord with ~4 ft of #10 twisted pair cable; 2- Turned up the no-load voltage on the Actron linear supply to 14.2 v which gives me better than 13.5v @ 100w key down on the K3 display and 3- reran the K3 Power Cal procedure with the K3 Utility. It's been fine ever since. GL+HNY

73,
Brian, K0DTJ

> On Dec 30, 2017, at 18:51, Mal Speer <[hidden email]> wrote:
>
> I seem to have low output on 75 phone. The most power I can put out is 71
> watts. I can turn the power knob to 100 watts, but it backs down to 71
> immediately. This is into an antenna and a dummy load.
>

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Wes Stewart-2

Re: 80 meters

In reply to this post by Jim Brown-10

IMD is also frequency sensitive.

Wes N7WS'

On 12/31/2017 12:17 PM, Jim Brown wrote:
> It's important to realize that IMD in many rigs, including the K3, increases
> with power output AND with reduced power supply voltage

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Re: 80 meters

In reply to this post by Mal Speer

Hi Mal,

There was a bunch of advice so far on the list, did any of that help you?

73,
Barthold
AD0RM

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Mal Speer
Sent: Saturday, December 30, 2017 7:52 PM
To: [hidden email]
Subject: [Elecraft] 80 meters

I seem to have low output on 75 phone. The most power I can put out is 71
watts. I can turn the power knob to 100 watts, but it backs down to 71
immediately. This is into an antenna and a dummy load.

I just checked 160 same thing except I get 83 watts

All other bands seem OK

Mal WA2TWA

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