K3 TX spurs?

[Rose]

I think I recall a thread about spurs being produced by
a K3's TX, but didn't pay enough attention at the time.

I've since become aware of a K3 that appeared to have
two spurs showing up on my P3.  They were about 30db
down from his very strong carrier on 7031 KHZ, and equally
spaced about 1 KHZ on either side. They both could be
"tuned in" and copied as individual signals.  I was surprised
when I asked the fella what his rig was and he told me it is a
K3. (;-)

I have -not- seen these spurs appear on other strong signals
since this event, and follow-up tests with him have not shown
the spurs ... but ... I've not seen his signal as strong as it was
at the time.

There's no doubt they were "real", but what might be the
cause?  Is / was the problem with his K3, my K3 or my P3.

Thoughts?

73!

Ken Kopp - K0PP
[hidden email]
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[Scott Ellington]

During the recent NAQP, I heard these 1 kHz sidebands on a nearby station's signal on 160.  (Perhaps the same station Ken heard?)  It turns out, his K3 was overloading his wimpy power supply, and making it go into current limit.  There was no sign of the spurs at slightly lower power.  He could see fluctuations in the supply voltage on the K3 internal meter whenever the spurs appeared.  With an adequate power supply, of course, the K3 is very, very clean.

By the way, while we were checking that out we did a quick comparison of key clicks from my K3 and FT-1000D (with the W8JI mods).  The K3 was much better.  And I know the FT-1000D was much worse before the mods.   It is best to have neighbors with K3's.  (But with good power supplies.)

73,

Scott  K9MA


On Jan 18, 2011, at 12:40 PM, Rose wrote:

> I think I recall a thread about spurs being produced by
> a K3's TX, but didn't pay enough attention at the time.
>
> I've since become aware of a K3 that appeared to have
> two spurs showing up on my P3.  They were about 30db
> down from his very strong carrier on 7031 KHZ, and equally
> spaced about 1 KHZ on either side. They both could be
> "tuned in" and copied as individual signals.  I was surprised
> when I asked the fella what his rig was and he told me it is a
> K3. (;-)
>
> I have -not- seen these spurs appear on other strong signals
> since this event, and follow-up tests with him have not shown
> the spurs ... but ... I've not seen his signal as strong as it was
> at the time.
>
> There's no doubt they were "real", but what might be the
> cause?  Is / was the problem with his K3, my K3 or my P3.
>
> Thoughts?
>
> 73!
>
> Ken Kopp - K0PP
> [hidden email]
> ______________________________________________________________
>

Scott Ellington
Madison, Wisconsin
USA



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[Willard Myers]

One possibility: “microphonics” modulating the synthesizer. The source is typically the sidetone being played through the internal speaker. A quick fix is to not use the internal speaker. The solid fix is the Elecraft synthesizer stiffener mod kit.

Easy to determine if this is the problem: change PITCH and see if the offset of the spurs changes.

I’ve seen this on a friend’s unit. The spurs were present, but diminished, with an external speaker. The mod kit stamped them out.

  Bill, K1GQ

On 2011.01.18, at 13:40, Rose wrote:

> I think I recall a thread about spurs being produced by
> a K3's TX, but didn't pay enough attention at the time.
>
> I've since become aware of a K3 that appeared to have
> two spurs showing up on my P3.  They were about 30db
> down from his very strong carrier on 7031 KHZ, and equally
> spaced about 1 KHZ on either side. They both could be
> "tuned in" and copied as individual signals.  I was surprised
> when I asked the fella what his rig was and he told me it is a
> K3. (;-)
>
> I have -not- seen these spurs appear on other strong signals
> since this event, and follow-up tests with him have not shown
> the spurs ... but ... I've not seen his signal as strong as it was
> at the time.
>
> There's no doubt they were "real", but what might be the
> cause?  Is / was the problem with his K3, my K3 or my P3.
>
> Thoughts?
>
> 73!
>
> Ken Kopp - K0PP
> [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

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[W8JH]

There was a serious spur problem with K3's that have C3 installed.  Read about it at: http://elecraft.365791.n2.nabble.com/Unstable-KPA3-100W-td5742537.html#a5742613

73,

Joe  W8JH
K3 1713