[Elecraft] Computer RFI in K2 -- Follow-Up

[Joe Subich, W4TV]

 > I've definitely verified that it's the polling from the two laptops. 
Increasing the polling interval correspondingly decreases the cycling 
frequency. It's quite tolerable with the polling set at 50, but it would 
be nicer not to have the problem at all. I'm still open to any advice 
from anyone who's dealt with this in the past.

My experience with reports of this kind generally resolve to an open 
ground/shield on the USB cable.  The first thing to try is a different 
USB cable (if the cable is not "captive") and a different serial
converter if you can't replace the cable.

The data rate on the USB side of the serial converter is higher than
that on the RS-232 side and generally causes the largest part of the
noise problem.

73,

    ... Joe, W4TV

On 7/6/2010 10:43 PM, J. Wolf wrote:
> I've definitely verified that it's the polling from the two laptops.
 > Increasing the polling interval correspondingly decreases the cycling
 > frequency. It's quite tolerable with the polling set at 50, but it
 > would be nicer not to have the problem at all. I'm still open to any
 > advice from anyone who's dealt with this in the past.
> --Jeff, K6JW
>    ----- Original Message -----
>    From: J. Wolf
>    To: elecraft at mailman.qth.net
>    Sent: Tuesday, July 06, 2010 1:13 PM
>    Subject: Computer RFI in K2
>
>
>       Recently, I made up the cable to connect my K2/100 to both the KAT100 ATU and my laptop. Everything works just fine...except for RFI from the computer to the radio when any of several logging programs is loaded (N1MM and CommCat being my two main programs). It sounds like a rapidly cycling change in the radio's noise level, and the S-meter reflects this, going from a baseline band noise level up to S9 with a period of just under a second. I've tried ferrite beads on everything, better grounding of the radio, and just connecting to the computer without the ATU, but nothing seems to have worked. The RFI isn't getting in via the coax feedline, since disconnecting it has no effect. In desperation, I tried a different laptop but got the same problem. The connection is via a serial to USB converter, and I've tried two different ones with no resolution of the problem. There's NO problem when the computer is running without either of the logging programs booted, so I'm guess
ing
>   this might have something to do with polling. Does anyone have any experience with this and, if so, any suggestions?
>    Jeff, K6JW
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