K3 - "Birdies" on P3 that tracks VFO A

[K9QJS]

Folks,  

I’m just seeing, today, that there are “birdies” for lack of a better term that appear on my P3 and which track my VFO and which are up 50 to 65 Khz up from where VFO A is located.   This wasn’t happening yesterday.    There are four lines about 5 Khz apart.  

What factors might be at work that result in this phenomenon?   The second question would be, what to do to remove them?    

73,
Hoop K9QJS

Photo of my P3 on Dropbox here, after I had just turned VFO A:  
 https://dl.dropboxusercontent.com/u/8335905/IMG_4560.jpg <https://dl.dropboxusercontent.com/u/8335905/IMG_4560.jpg>


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[K9QJS]

George,

Thanks,  

And my problem is different and I have solved it.   I am feeling silly…    My antenna switch was not on an antenna.    Sorry for the bandwidth.    

Hoop


On Sep 5, 2016, at 11:32 AM, Gmail - George <[hidden email]> wrote:

Hoop,
I had a similar problem several years ago.
It was a bad BNC cable on the K3 to P3 IF cable. One of the ground
connections was poor at the connector.
Try "Wiggling" the cable to see if it changes or goes away or even gets
worse.
73
George
AI4VZ


-----Original Message-----
From: J.K. Hooper
Sent: Monday, September 5, 2016 2:17 PM
To: Elecraft Reflector
Subject: [Elecraft] K3 - "Birdies" on P3 that tracks VFO A

Folks,

I’m just seeing, today, that there are “birdies” for lack of a better term
that appear on my P3 and which track my VFO and which are up 50 to 65 Khz up
from where VFO A is located.   This wasn’t happening yesterday.    There are
four lines about 5 Khz apart.

What factors might be at work that result in this phenomenon?   The second
question would be, what to do to remove them?

73,
Hoop K9QJS

Photo of my P3 on Dropbox here, after I had just turned VFO A:
https://dl.dropboxusercontent.com/u/8335905/IMG_4560.jpg 
<https://dl.dropboxusercontent.com/u/8335905/IMG_4560.jpg>


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[Jim Brown-10]

On Mon,9/5/2016 11:17 AM, J.K. Hooper wrote:
> What factors might be at work that result in this phenomenon?

Hoop,

I've encountered this as well. There are two problems (at least). The
strong, intermittent birdies are probably caused by a flaky shield
connection in the coax cable between the P3 and the radio. Wiggle that
cable at both connectors (and make sure that the connectors are tight)
and they should go away. If they don't, replace the cable.

There are weaker birdies that show up on a quiet band -- I see them a
LOT on 6M, and they are a PITA when you're trying to use the P3 to look
for weak CW signals when the band is trying to open for double-hop
E-skip. Band noise will cover them if you have a high noise level. They
move in the opposite direction of the VFO, and they move much faster
than the VFO. I suspect they are the result of circuit layout issues
within the radio.

73, Jim K9YC

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[Bill Frantz]

When I find an unusual level of birdies on either panadapter, I
first look for antenna problems. I learned this in the school of
hard knocks.

73 Bill AE6JV

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[w4sc-2]

If you are not using the P3 IF OUT port, make sure that the switch (on the back panel) that inserts the 3db splitter is in the OFF position.  I have seen issues with the P3 IF OUT set to ON and no load (other SDR receiver, or TERMINATION) connected.  There is not an isolation buffer between the splitter and the IF OUT port, so there could be an issue with a signal being coupled back into the P3 A-to-D signal path from an external, or internal, source.

I have observed something very similar to the picture you posted with the P3 IN and OUT ports disconnected, but terminated.  The “birdies” drifted back and forth across the P3 display as it warmed up.  I managed to minimize the signals amplitude by following the P3 ribbon and IF cable dressing recommendation, but could not eliminate them.

de Ben W4SC
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