[Elecraft] K3 serial cable shielding / noise question

[G4ILO]

M1PAF wrote:
> 
> Hi list,
> 
> Bit of a strange issue here with serial comms between the PC and the K3.
> First a bit of description about my set up: I use an external noise sense
> antenna in addition to the main station antenna to cancel out some nasty
> local electrical noise with a Timewave ANC-4 noise phasing unit. This is
> connected to the RX out / RX in jacks on the transverter interface (this
> is a great feature).
> 
> The issue I have is this: when I use a USB serial adapter I get no
> additional noise issues when the computer is polling the rig. However, my
> computer has a serial port which I would rather use. I made up a cable
> with pins 2, 3, 4, 5, and 6 straight through and the cable shield soldered
> to the shell of the d-type that connects to the K3. When I use this cable
> the radio picks up bursts of noise from the noise sense antenna (which is
> not good if I'm using it to null out other local noise).
> 
> This is obviously radiation from the serial cable but I'm at a loss as to
> why (incidentally also tried some ferrites on the cable and they made no
> difference).
> 
> Any suggestions?
> 
> Thanks Paul M1PAF
> 
> 
Do you get this noise if you connect an audio cable between the computer and
the K3? This would help decide whether the noise is coming from the computer
itself (e.g. poorly suppressed power supply) being coupled to the radio via
the shield, or if it is being generated by the serial adapter in the PC.

-----
Julian, G4ILO  K3 s/n: 222 K2 s/n: 392
G4ILO's Shack: www.g4ilo.com
Zerobeat Ham Forums: www.zerobeat.net/smf
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