P3 Continuosly Offset Waterfall Trace

[K4SC]

The subject is terse, so here is what is happening.  I notice a very narrow but steady vertical line on my waterfall which does not move when I QSY.  This occurs only in CW mode and I can see it when the SPAN is narrow, ±5 kHz or less.  It appears to vary between bands but in the range of -600 to -800 Hz from the center frequency.  All other real signals track when I move the VFO, but this one just stays there, as if you drew a vertical line on the display.

As I am writing this description it occurred to me that it may be related to the CW sidetone, and sure enough, when I adjust the PITCH, the offset varies in relation to the center frequency of the P3 display.  In other words, when I raise the PITCH frequency the trace moves upwards; decreasing the delta between center and trace frequencies, and vice versa.   I put the radio in REVERSE CW mode to see if the trace would move to the positive side of the center frequency, but it just disappears.

I am a total novice to panadaptors or spectrum analyzers, so if this is a normal "thing", I am unaware.  It really does no harm, but I noticed it because I am using the waterfall a lot this weekend during the SKCC Weekend Sprint and I mistook it for a carrier that could never be heard.

I can not say whether it has been there all along or is a new quirk, as I just noticed it today.  I have removed and replaced all connections to the P3, ensuring their proper fit and tightness.

Any thoughts?  

[Bill W4ZV]

>As I am writing this description it occurred to me that it may be related to the CW sidetone, and sure enough, when I adjust the PITCH, the offset varies in relation to the center frequency of the P3 display.

Are you using the speaker?  If so it's possible the speaker audio is modulating the K3's VCO at the Pitch offset.  Try headphones and see if the line disappears.  If it does, then you may need to make the following mod:

http://www.elecraft.com/manual/ELECRAFT%20KSYN3%20Stiffener%20Mod%20Rev%20D.pdf

73,  Bill

[K4SC]

Thanks for the advice, but it is present, headphones or speaker.

[Alan Bloom-2]

Is there anything connected to the IF OUT connector on the P3?  We've
had reports of the LO signal from, for example, an LP-PAN leaking into
the P3 via that path.

Alan N1AL


On Sun, 2010-09-12 at 11:24 -0700, K4SC wrote:

> The subject is terse, so here is what is happening.  I notice a very narrow
> but steady vertical line on my waterfall which does not move when I QSY.
> This occurs only in CW mode and I can see it when the SPAN is narrow, ±5 kHz
> or less.  It appears to vary between bands but in the range of -600 to -800
> Hz from the center frequency.  All other real signals track when I move the
> VFO, but this one just stays there, as if you drew a vertical line on the
> display.
>
> As I am writing this description it occurred to me that it may be related to
> the CW sidetone, and sure enough, when I adjust the PITCH, the offset varies
> in relation to the center frequency of the P3 display.  In other words, when
> I raise the PITCH frequency the trace moves upwards; decreasing the delta
> between center and trace frequencies, and vice versa.   I put the radio in
> REVERSE CW mode to see if the trace would move to the positive side of the
> center frequency, but it just disappears.
>
> I am a total novice to panadaptors or spectrum analyzers, so if this is a
> normal "thing", I am unaware.  It really does no harm, but I noticed it
> because I am using the waterfall a lot this weekend during the SKCC Weekend
> Sprint and I mistook it for a carrier that could never be heard.
>
> I can not say whether it has been there all along or is a new quirk, as I
> just noticed it today.  I have removed and replaced all connections to the
> P3, ensuring their proper fit and tightness.
>
> Any thoughts?  
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/P3-Continuosly-Offset-Waterfall-Trace-tp5523982p5523982.html
> Sent from the [K3] mailing list archive at Nabble.com.
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