[DogParkList] Noise

[EZ Rhino]

Group,

I've been suffering through this same thing for a while.  It took me  
a while to figure out what it was...mostly because I'm a green ham,  
not because it was difficult to figure out.  (Not to be confused with  
green eggs and ham.)

Initially I used some transformer E cores (very good ferrites) to  
bring to noise down to the point where it wasn't so noticeable.  I  
wrapped the CiV cable around the core very near the interface box.   
(I was using a Black Cat CiV; now using USB Interface II.)

That was the band aid fix.  The problem for me was the simple fact  
that my iMac transmits noise which is being picked up by the antenna  
and sent into the radio.  Grounding the computer didn't help  
any...there was nothing wrong with Black Cat or USB Interface II  
either.  I think putting up my tower and beam a little further away  
from the shack helped in my case.  I've got some more emails in my  
work computer on this subject; I'll look for them on Monday and see  
if I can shed any more light on the subject.

I recall Mark B. from the 746 pro Yahoo group suggest hooking my  
feedline to a dummy load (to ensure the coax is acting like coax) and  
take the antenna out of the equation, then try to reproduce the noise.

Hope this helps,

Chris
KF7P




On Aug 25, 2007, at 7:34 PM, ltrranch at vtc.net wrote:


> Thanks for so many replies with suggestions. I have noticed the  

> noise in the past, however, like Jim said it seems worse today. I  

> do have a common ground to all equipment except the iBook lap top  

> which is located with couple feet of my IC-736. I did quickly  

> attach a ground to the computer and the common point, without any  

> drop in the noise level. I'm using the USB CI-V interface from  

> Black Cat Systems. I haven't tried toroids on the leads. Wouldn't  

> know which or where to purchase such. It would seem to me that the  

> offending noise being generated must have a specific frequency such  

> that it just causes interference on the 20 meter band. It could be  

> on other bands, but just not noticeable. Also, I've noticed the  

> Cocoa Modem program doesn't cause noise. Will try the battery idea  

> tomorrow. Thanks Tom N7KCX

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