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K3 Spur on 160??!!

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Mike Furrey

K3 Spur on 160??!!

After the CQWW 160 contest this past weekend, I checked my signals on the Reverse Beacon Network and it appeared that the AC0C skimmer (545 miles NW of me) was picking up a spur on 1855.7 kHz! This occurred only at the AC0C skimmer and did not show on any other skimmers and only when I was running on 1830.3 kHz and did not show when I was running on any other frequency. I have done a cut-and-paste below. I was using my K3 barefoot and my antenna is an inverted L with one elevated radial up 20 feet.

Is this something I should be concerned about?
73, Mike WA5POK

| AC0C | WA5POK | 1830.3 | CW CQ | 38 dB | 25 wpm | 0919z 31 Jan |
| AC0C | WA5POK | 1855.7 | CW CQ | 13 dB | 25 wpm | 0919z 31 Jan |
| K1TTT | WA5POK | 1830.3 | CW CQ | 2 dB | 26 wpm | 0919z 31 Jan |
| AC0C | WA5POK | 1830.1 | CW CQ | 14 dB | 25 wpm | 0919z 31 Jan |
| AC0C | WA5POK | 1855.7 | CW CQ | 13 dB | 25 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1830.3 | CW CQ | 39 dB | 25 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1830.3 | CW CQ | 37 dB | 26 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1855.7 | CW CQ | 11 dB | 25 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1830.3 | CW CQ | 40 dB | 25 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1855.7 | CW CQ | 11 dB | 25 wpm | 0917z 31 Jan |

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Milt -- N5IA

Re: K3 Spur on 160??!!

Mike,

From my remote station which was operated by KY7M in the contest, I noticed
the same thing from the AC0C RBN box.

However, in this case the QRG of KY7M was 1.820.6 and the other recorded
transmission by AC0C was 1.864.7, a 44.4 kHz difference.

Your noted difference was 25.4 kHz.

Perhaps someone smarter than me can figure it out. BUT, I am sure the
problem is with the AC0C receiver and NOT our K3 transmitters.

73 to all de Milt, N5IA

AC0C KY7M 1864.7 CW CQ [LoTW] 21 dB 26 wpm 0416z 02 Feb
W4KKN KY7M 1820.6 CW CQ [LoTW] 25 dB 25 wpm 0415z 02
Feb
AC0C KY7M 1820.6 CW CQ [LoTW] 21 dB 26 wpm 0415z 02 Feb
AC0C KY7M 1864.7 CW CQ [LoTW] 26 dB 26 wpm 0415z 02 Feb
AC0C KY7M 1820.6 CW CQ [LoTW] 17 dB 25 wpm 0414z 02 Feb
AC0C KY7M 1864.7 CW CQ [LoTW] 27 dB 25 wpm 0413z 02 Feb
AC0C KY7M 1820.6 CW CQ [LoTW] 27 dB 26 wpm 0413z 02 Feb
AC0C KY7M 1864.7 CW CQ [LoTW] 24 dB 26 wpm 0413z 02 Feb
AC0C KY7M 1864.7 CW CQ [LoTW] 26 dB 25 wpm 0412z 02 Feb
AC0C KY7M 1820.6 CW CQ [LoTW] 25 dB 26 wpm 0411z 02 Feb
AC0C KY7M 1864.7 CW CQ [LoTW] 25 dB 26 wpm 0411z 02 Feb
AC0C KY7M 1820.6 CW CQ [LoTW] 16 dB 26 wpm 0410z 02 Feb
AC0C KY7M 1864.7 CW CQ [LoTW] 25 dB 26 wpm 0410z 02 Feb
WZ7I KY7M 1820.6 CW CQ [LoTW] 34 dB 27 wpm 0410z 02 Feb
AC0C KY7M 1820.6 CW CQ [LoTW] 20 dB 26 wpm 0410z 02 Feb
AC0C KY7M 1864.7 CW CQ [LoTW] 26 dB 26 wpm 0409z 02 Feb
AC0C KY7M 1820.6 CW CQ [LoTW] 18 dB 25 wpm 0409z 02 Feb

-----Original Message-----
From: Mike Furrey
Sent: Monday, February 01, 2016 9:49 PM
To: Elecraft Reflector
Subject: [Elecraft] K3 Spur on 160??!!

After the CQWW 160 contest this past weekend, I checked my signals on the
Reverse Beacon Network and it appeared that the AC0C skimmer (545 miles NW
of me) was picking up a spur on 1855.7 kHz! This occurred only at the AC0C
skimmer and did not show on any other skimmers and only when I was running
on 1830.3 kHz and did not show when I was running on any other frequency. I
have done a cut-and-paste below. I was using my K3 barefoot and my antenna
is an inverted L with one elevated radial up 20 feet.

Is this something I should be concerned about?
73, Mike WA5POK

| AC0C | WA5POK | 1830.3 | CW CQ | 38 dB | 25 wpm | 0919z 31 Jan |
| AC0C | WA5POK | 1855.7 | CW CQ | 13 dB | 25 wpm | 0919z 31 Jan |
| K1TTT | WA5POK | 1830.3 | CW CQ | 2 dB | 26 wpm | 0919z 31 Jan |
| AC0C | WA5POK | 1830.1 | CW CQ | 14 dB | 25 wpm | 0919z 31 Jan |
| AC0C | WA5POK | 1855.7 | CW CQ | 13 dB | 25 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1830.3 | CW CQ | 39 dB | 25 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1830.3 | CW CQ | 37 dB | 26 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1855.7 | CW CQ | 11 dB | 25 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1830.3 | CW CQ | 40 dB | 25 wpm | 0918z 31 Jan |
| AC0C | WA5POK | 1855.7 | CW CQ | 11 dB | 25 wpm | 0917z 31 Jan |

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Guy Olinger K2AV

Re: K3 Spur on 160??!!

Folks, this is an image in the radio, and has to do with where the center
of the SDR range is set. It's a problem that any RBN node potentially has
depending on their equipment. It's a known problem with simpler SDRs, or
with a more expensive SDR with something on the fritz.

Don't tear your K3 apart looking for the problem or send it to Big E.

AC0C will have to deal with it.

73, Guy K2AV

On Tue, Feb 2, 2016 at 12:27 AM, Milt -- N5IA <[hidden email]>
wrote:

> Mike,
>
> From my remote station which was operated by KY7M in the contest, I
> noticed the same thing from the AC0C RBN box.
>
> However, in this case the QRG of KY7M was 1.820.6 and the other recorded
> transmission by AC0C was 1.864.7, a 44.4 kHz difference.
>
> Your noted difference was 25.4 kHz.
>
> Perhaps someone smarter than me can figure it out. BUT, I am sure the
> problem is with the AC0C receiver and NOT our K3 transmitters.
>
> 73 to all de Milt, N5IA
>
> AC0C KY7M 1864.7 CW CQ [LoTW] 21 dB 26 wpm 0416z 02
> Feb
> W4KKN KY7M 1820.6 CW CQ [LoTW] 25 dB 25 wpm 0415z 02
> Feb
> AC0C KY7M 1820.6 CW CQ [LoTW] 21 dB 26 wpm 0415z 02
> Feb
> AC0C KY7M 1864.7 CW CQ [LoTW] 26 dB 26 wpm 0415z 02
> Feb
> AC0C KY7M 1820.6 CW CQ [LoTW] 17 dB 25 wpm 0414z 02
> Feb
> AC0C KY7M 1864.7 CW CQ [LoTW] 27 dB 25 wpm 0413z 02
> Feb
> AC0C KY7M 1820.6 CW CQ [LoTW] 27 dB 26 wpm 0413z 02
> Feb
> AC0C KY7M 1864.7 CW CQ [LoTW] 24 dB 26 wpm 0413z 02
> Feb
> AC0C KY7M 1864.7 CW CQ [LoTW] 26 dB 25 wpm 0412z 02
> Feb
> AC0C KY7M 1820.6 CW CQ [LoTW] 25 dB 26 wpm 0411z 02
> Feb
> AC0C KY7M 1864.7 CW CQ [LoTW] 25 dB 26 wpm 0411z 02
> Feb
> AC0C KY7M 1820.6 CW CQ [LoTW] 16 dB 26 wpm 0410z 02
> Feb
> AC0C KY7M 1864.7 CW CQ [LoTW] 25 dB 26 wpm 0410z 02
> Feb
> WZ7I KY7M 1820.6 CW CQ [LoTW] 34 dB 27 wpm 0410z 02
> Feb
> AC0C KY7M 1820.6 CW CQ [LoTW] 20 dB 26 wpm 0410z 02
> Feb
> AC0C KY7M 1864.7 CW CQ [LoTW] 26 dB 26 wpm 0409z 02
> Feb
> AC0C KY7M 1820.6 CW CQ [LoTW] 18 dB 25 wpm 0409z 02
> Feb
>
>
> -----Original Message----- From: Mike Furrey
> Sent: Monday, February 01, 2016 9:49 PM
> To: Elecraft Reflector
> Subject: [Elecraft] K3 Spur on 160??!!
>
> After the CQWW 160 contest this past weekend, I checked my signals on the
> Reverse Beacon Network and it appeared that the AC0C skimmer (545 miles NW
> of me) was picking up a spur on 1855.7 kHz! This occurred only at the AC0C
> skimmer and did not show on any other skimmers and only when I was running
> on 1830.3 kHz and did not show when I was running on any other frequency. I
> have done a cut-and-paste below. I was using my K3 barefoot and my antenna
> is an inverted L with one elevated radial up 20 feet.
>
> Is this something I should be concerned about?
> 73, Mike WA5POK
>
> | AC0C | WA5POK | 1830.3 | CW CQ | 38 dB | 25 wpm | 0919z 31 Jan |
> | AC0C | WA5POK | 1855.7 | CW CQ | 13 dB | 25 wpm | 0919z 31 Jan |
> | K1TTT | WA5POK | 1830.3 | CW CQ | 2 dB | 26 wpm | 0919z 31 Jan |
> | AC0C | WA5POK | 1830.1 | CW CQ | 14 dB | 25 wpm | 0919z 31 Jan |
> | AC0C | WA5POK | 1855.7 | CW CQ | 13 dB | 25 wpm | 0918z 31 Jan |
> | AC0C | WA5POK | 1830.3 | CW CQ | 39 dB | 25 wpm | 0918z 31 Jan |
> | AC0C | WA5POK | 1830.3 | CW CQ | 37 dB | 26 wpm | 0918z 31 Jan |
> | AC0C | WA5POK | 1855.7 | CW CQ | 11 dB | 25 wpm | 0918z 31 Jan |
> | AC0C | WA5POK | 1830.3 | CW CQ | 40 dB | 25 wpm | 0918z 31 Jan |
> | AC0C | WA5POK | 1855.7 | CW CQ | 11 dB | 25 wpm | 0917z 31 Jan |
>
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>

Jim Brown-10

Re: K3 Spur on 160??!!

In reply to this post by Mike Furrey

On Mon,2/1/2016 8:49 PM, Mike Furrey wrote:
> it appeared that the AC0C skimmer (545 miles NW of me) was picking up a spur on 1855.7 kHz!

It is not uncommon for skimmers to have spurious responses.

73, Jim K9YC
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wayne burdick

Re: K3 Spur on 160??!!

Administrator

In reply to this post by Milt -- N5IA

"Milt -- N5IA" <[hidden email]> wrote:

> Mike,
>
> From my remote station which was operated by KY7M in the contest, I noticed the same thing from the AC0C RBN box.
>
> ....BUT, I am sure the problem is with the AC0C receiver and NOT our K3 transmitters.

This could happen if the receiver in use was subjected to a signal beyond its usable dynamic range. For example, a very strong carrier could mix with another strong station's CW to create "ghost" signals (third-order intermod) for the duration of the carrier. Another possibility is demodulating a strong signal due to a spur in the receiver's local oscillator. Such scenarios are much more likely during heavy contest activity.

Wayne
N6KR

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Joe Subich, W4TV-4

Re: K3 Spur on 160??!!

In this case it looks as if the AC0C has a simple SDR with an I/Q
balance problem. In both cases reported the "spur" is equal distant
on 1,842.65 KHz.

73,

... Joe, W4TV

On 2/2/2016 12:46 AM, Wayne Burdick wrote:

> "Milt -- N5IA" <[hidden email]> wrote:
>
>> Mike,
>>
>> From my remote station which was operated by KY7M in the contest, I noticed the same thing from the AC0C RBN box.
>>
>> ....BUT, I am sure the problem is with the AC0C receiver and NOT our K3 transmitters.
>
> This could happen if the receiver in use was subjected to a signal beyond its usable dynamic range. For example, a very strong carrier could mix with another strong station's CW to create "ghost" signals (third-order intermod) for the duration of the carrier. Another possibility is demodulating a strong signal due to a spur in the receiver's local oscillator. Such scenarios are much more likely during heavy contest activity.
>
> Wayne
> N6KR
>

Mike Furrey

Re: K3 Spur on 160??!!

After reading everyone's posts (THANKS!) and doing a bit more digging, I found this on the reverse beacon web page:http://content.reversebeacon.net/sites/reversebeacon.net/files/users/user3/The%20RBN%20and%20You.pdf
About half way down, "Images from mis-adjusted receivers – two spots, same call, different frequencies" ... the whole thing is a good read.
So I have concluded the K3 is just fine. 100 watts to the inverted L netted me 615 Qs in the contest.
73, Mike WA5POK

On Tuesday, February 2, 2016 6:51 AM, "Joe Subich, W4TV" <[hidden email]> wrote:

In this case it looks as if the AC0C has a simple SDR with an I/Q
balance problem. In both cases reported the "spur" is equal distant
on 1,842.65 KHz.

73,

... Joe, W4TV

On 2/2/2016 12:46 AM, Wayne Burdick wrote:

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