pulsing hash

[richard gilley-2]

When running KComm, on the K2 as a logging program, I hear a pulsing  
hash, a varying amplitude hash with a peak rate of a few seconds.  
More prevalent on 40 meters, reducing a bit on 20 meters.
When I disconnect all is OK.  The hash is not that disturbing but if  
you tend to pay attention it could be bothersome.   Any ideas?
Thank you for your attention.
Best regards
Dick AD1G 73
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[Arie Kleingeld PA3A-2]

Dick,

This could be the KIO2 cable inside the K2, running from the serial
connector to the control board.
If it sags down, this will cause that kind of hash because it is too
close to the receiver circuitry.
Keep this cable as close to the topcover as you can.

73
Arie PA3A

-----Oorspronkelijk bericht-----
Van: [hidden email]
[mailto:[hidden email]] Namens richard gilley
Verzonden: donderdag 24 september 2009 2:52
Aan: [hidden email]
Onderwerp: [Elecraft] pulsing hash


When running KComm, on the K2 as a logging program, I hear a pulsing  
hash, a varying amplitude hash with a peak rate of a few seconds.  
More prevalent on 40 meters, reducing a bit on 20 meters.
When I disconnect all is OK.  The hash is not that disturbing but if  
you tend to pay attention it could be bothersome.   Any ideas?
Thank you for your attention.
Best regards
Dick AD1G 73
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[Julian, G4ILO]

Arie Kleingeld PA3A-2 wrote

Dick,

This could be the KIO2 cable inside the K2, running from the serial
connector to the control board.
If it sags down, this will cause that kind of hash because it is too
close to the receiver circuitry.
Keep this cable as close to the topcover as you can.

If it isn't that, then it might be due to the use of a USB to serial adapter. Real serial ports tend to be quieter.

This thread: http://n2.nabble.com/Re-serial-interface-noise-on-160m-propagates-through-K3-td3137659.html#a3137659
contains some information that might be helpful.

[Julian, G4ILO]

Arie Kleingeld PA3A-2 wrote

Dick,

This could be the KIO2 cable inside the K2, running from the serial
connector to the control board.
If it sags down, this will cause that kind of hash because it is too
close to the receiver circuitry.
Keep this cable as close to the topcover as you can.

If it isn't that, then it might be due to the use of a USB to serial adapter. Real serial ports tend to be quieter. Some have found that it is important to have continuity through the cable shielding from the K2 right through to the computer.

[Jim Brown-10]

On Thu, 24 Sep 2009 06:46:05 -0700 (PDT), Julian, G4ILO wrote:

>Some have found that it is important to have continuity through the
>cable shielding from the K2 right through to the computer.

Yes, and also to use twisted pairs for each signaling circuit between
computer and radio. See http://audiosystemsgroup.com/RFI-Ham.pdf  and
http://audiosystemsgroup.com/HamInterfacing.pdf for descriptions of a
serial cable that fixes problems like this. My initial experiments on
this were the result of serious RFI issues with the K2 serial cable in
close proximity to a long wire TX antenna that I used on 80M and 160M.

Another point. Cable shielding IS a good thing, but using twisted pairs
and terminating them to the chassis at each end, NOT to the circuit
board, is the most important thing.

73,

Jim Brown K9YC



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[richard gilley-2]

Thank you all for your response. The hash is no longer heard.  As  
PA3A suggested, moving the inter connect ribbon cable up and away  
from the main K2 RF board solved the problem.
Appreciate your consideration.
73
Dick AD1G


Begin forwarded message:

> When running KComm, on the K2 as a logging program, I hear a pulsing
> hash, a varying amplitude hash with a peak rate of a few seconds.
> More prevalent on 40 meters, reducing a bit on 20 meters.
> When I disconnect all is OK.  The hash is not that disturbing but if
> you tend to pay attention it could be bothersome.   Any ideas?
> Thank you for your attention.
> Best regards
> Dick AD1G 73
> ______________________________________________________________
> 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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