K2/100 RS-232 Noise

[Pierre]

>Hi Pierre.. YES, I did leave the freq counter cable. Is that the problem?
>I'm at work right now and can't test it.
>Thanks.. David, W4SMT

David,

I just wanted to know if your cable was still in place before opening my K2.
I have the same noise problem, especially on 20 m, and guessed that the
cable was the cause of it.

So, I just removed the counter cable.. (and changed the ribbon's position),
but that noise is still present. So, back to square one.. ??

73 de Pierre VE2PID

K2 S/N 5170

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[David Fleming-4]

Removing the freq counter cable had no effect. Repositioning the ribbon
cable did help some, but the noise is still there.  I tried positioning
the cable every way possible and found the most quite spot by routing it
back beneath the shield and then folding it sharply toward the front -
right above but not touching the crystals on KSB2.  I taped the cable
to the shield at this spot.  Without an antenna, the noise is still ~S2
(2 leds) on most bands. But with an antenna attached it disappears into
the band noise.  So I suppose it's not too big a deal. But I'd still
like to get rid of the noise completely. I never noticed it with the
KIO2. I also changed the polling frequency to 1 second. That makes the
noise more or less insignificant. But now I have to look at the rig's
S-meter instead of the virtual one on the monitor. :)

Anyways, the K2 is working *great*.  It a real joy to operate and the
receiver is simply fantastic. I'll be taking it on a DX vacation to
Bermuda the last week in July.  I'm looking forward to finding out what
it's like to "BE" DX. :)

73

-David W4SMT  

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[Don Wilhelm-3]

David,

It is usually best to fan-fold the cable so it entirely tucks up into
the corner at the top of the control board - and do the same thing with
the speaker cable.  Removing the right side panel to dress the cable is
the easiest way to accomplish the feat.

Keep the cables as far away from the KSB2 board as possible.

73,
Don W3FPR

David Fleming wrote:

> Removing the freq counter cable had no effect. Repositioning the ribbon
> cable did help some, but the noise is still there.  I tried positioning
> the cable every way possible and found the most quite spot by routing it
> back beneath the shield and then folding it sharply toward the front -
> right above but not touching the crystals on KSB2.  I taped the cable
> to the shield at this spot.  Without an antenna, the noise is still ~S2
> (2 leds) on most bands. But with an antenna attached it disappears into
> the band noise.  So I suppose it's not too big a deal. But I'd still
> like to get rid of the noise completely. I never noticed it with the
> KIO2. I also changed the polling frequency to 1 second. That makes the
> noise more or less insignificant. But now I have to look at the rig's
> S-meter instead of the virtual one on the monitor. :)
>
> Anyways, the K2 is working *great*.  It a real joy to operate and the
> receiver is simply fantastic. I'll be taking it on a DX vacation to
> Bermuda the last week in July.  I'm looking forward to finding out what
> it's like to "BE" DX. :)
>
> 73
>
> -David W4SMT  
>
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>

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[Jim Brown-10]

I suggest a different solution. Rebuild the serial cable using the
techniques detailed in Chapter 8 of my RFI tutorial.

http://audiosystemsgroup.com/RFI-Ham.pdf

Also, the coupling mechanism for the noise is very likely a "pin 1
problem," also discussed in that tutorial. The ONLY good termination for
a cable shield is the shielding enclosure (the chassis) of the equipment
on each end. When you tie the shield to the "audio ground" or "control
ground" or "signal ground," it allows the cable shield to radiate RF
trash from the equipment, and it also allows the cable shield to RECEIVE
RF from your transmitting antenna (also known as RF feedback, or "RF in
the shack").

73,

Jim Brown K9YC


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