[Elecraft] RS232 Noise

[Mike Harris]

Hi Tom,

I'm beginning to wonder if it might not be due to shorting out the chokes 
for PC out and PC in of the RS232 connector whilst doing the rear panel RF 
immunity mods.

The problem is I don't have a "before" benchmark.  I can now hear PC 
activity, screen update (the seconds ticking by in WSJT).
----- Original Message ----- 
From: "Radio Amateur N5GE" <n5ge at n5ge.com>
To: "Mike Harris" <mike.harris at horizon.co.fk>
Cc: "Reflector Elecraft" <Elecraft at mailman.qth.net>
Sent: Wednesday, April 22, 2009 8:08 PM
Subject: Re: [Elecraft] RS232 Noise


On Wed, 22 Apr 2009 19:11:51 -0400, "Mike Harris"
<mike.harris at horizon.co.fk> wrote:

Being concerned by your report, I checked my K3 #806 and did not
experience the symptom you describe.

Tom, N5GE
K3 #806, K3 #1055
XV144, XV432
W1 and other small kits.
http://www.n5ge.com

>G'day,
>
>Just in case anyone is interested.
>
>Today I was investigating the effectiveness on a local 6m low level 
>signal
>of the various combinations of NO PREAMP, K3 PREAMP ONLY, PR6 ONLY, K3
>PREAMP + PR6 in preparation for a 6m EME test.
>
>All was as expected then I turned on the PC.  With the two preamps in 
>line
>there was a 1-2 S-point increase in background noise (SSB bandwidth).
>This extra noise vanished when I removed the "RS232" cable from the K3.
>The cable is actually the one I made up for the K2.
>
>Touching the shell of the connector to the K3 shell didn't restore the
>noise, only when actually inserting the pins did it come back.
>
>No noise being carried on the two audio leads to/from the PC so no big
>deal the disconnect the RS232 during the moon run.
>
>No further investigations to date.
>
>Regards,
>
>Mike VP8NO
>
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