[Elecraft] K2 KIO2 Serial Data causes RX Interference

[Julian, G4ILO]

Stephen Arnold wrote:
> 
> Hi All,
> 
> I hope that someone out there might be able to help me with this one.
> 
> What I have is a basic K2 with KAT2 internal tuner (KSB2 and KBT2 are also
> installed). Then I also have the KPA100 outboard in a EC2 with the
> KAT100-2.
> 
> To say it another way (without all those K's ;-) what we have is the "K2
> Twins".
> 
> All works very nicely (thankyou Elecraft!!) except that I am now starting
> to play with digital modes.
> 
> I have the K2 connected to an Asus Eee PC running Linux (Mandriva 2008.1).
> When I run the fldigi software and tell it to use hamlib to perform rig
> control everything works perfectly BUT...
> 
> I now have RX audio interference. It sounds like a low volume puffing
> steam train or a chuff-chuff type noise. It is pretty obvious what is
> causing it. The constant serial data stream being sent by the fldigi
> program.
> 
> The interference is all bands and all frequencies so far as I can tell. It
> is very low level but quite audible and would drive you mad if you tried
> to use the radio for any length without turning the volume down. Needless
> to say it will no doubt play havoc with weak digital signals.
> 
> Questions is: Am I looking at a fault in my particular K2 set-up or just a
> design limitation? (you would never notice the issue except for the
> constant polling by fldigi). And how does one go about trying to fix the
> problem?
> 
> Any ideas, anyone?
> 
> 
I have used a K2 on data modes for years without observing anything like you
describe. I doubt that it is anything in the K2 that is causing the problem.

My experience of USB devices is that some of these can cause low level wide
band interference. I once had the bright idea of using a cheap USB soundcard
as an extra audio input for a second receiver - the noise it generated more
or less wiped out the signals I was trying to decode.

So my guess is that your USB to serial connector is the culprit.

-----
Julian, G4ILO
http://www.g4ilo.com/ G4ILO's Shack 
http://www.ham-directory.com/ Ham Directory 
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