eHam Forums => Computers And Software => Topic started by: VA7DXC on December 03, 2009, 03:23:32 AM

Title: CI-V Cable noise?
Post by: VA7DXC on December 03, 2009, 03:23:32 AM
Just trying to setup a Rigblaster Plug & Play with my IC-7000. All is working ok until I plug in the CAT control cable from the back of the transceiver to the play & play box. The functionality is working ok, I can control the rig in HRD, N1MM etc but the RX audio is now plagued with a weird cyclical switching/ticking sound.

The noise only occurs when the control cable is in use by the software. When the software is closed but with the cable still plugged-in the noise cannot be heard. I've tried it on both a desktop and laptop with the same results. I can actually hear the clicking/switching noise in my desktop PC when the CAT cable is in use by HRD.

I'm guessing the noises are the actual control/switching signals generated in the PC? Has anybody come across this before and what has been the remedy? I'm guessing some amount of ferrite may choke it off but want to be sure before I go and part with more cash.

Title: RE: CI-V Cable noise?
Post by: G4GOY on December 03, 2009, 04:18:52 AM

A friend of mine had exactly the same problem.  Its caused by HRD polling the transceiver for status updates.  I believe he solved the problem by using ferrites on the CAT cable

Best 73,
John G4GOY

Title: RE: CI-V Cable noise?
Post by: VA7DXC on December 04, 2009, 12:28:09 PM
I had an old ferrite rod lying around, not sure what mix it was. About ten turns seems to choke off the noise above 12Mhz or so. I might have to go and get some more though to make 30m usable. 80m is the worst, the noise is S9 and I don't think any amount of ferrite is going to solve that.

I've confirmed that the noise is generated interally by the PC. It is the polling signal created by any software that controls the radio over CI-V.

So to really solve the problem I probably need to opto-isolate the CI-V lead between the rig and the PnP box. Should be simple to find plans for that because  it's only a simple mono to stereo 3.5mm patch cable.