[DSP-10] CW transmit has a raspy sound

[David and Brenda Holman]

Some bypass capacitors in various areas.  It might take some tinkering 
to figure exactly where.  Maybe try some better shielding, solid metal, 
grounded box and see if the problem goes away.  You might also want to 
try putting a ferrite bead or filter on the cables coming.  The 
fluorescent lights both radiate and conduct through the power lines. 

The biggest pain is going to be figuring out first if it really is the 
fluorescent lights and then figuring out where it is getting in.  As a 
test try shutting off the lights and operate in the dark.  If the 
problem goes away, you know where it is coming from.  You might also 
want to try operating from a battery, in the dark. 

Hope that helps

David, KE3HF


Ron Meiring wrote:

>Mhhh could be true, I have got the raspy audio and the fluorescent 
>lights .....
>However can't get rid of the lights ...
>How do I get rid of the magnetic problems >?
>
>Cheers
>Ron VK6KDD
>
>On Tue, 20 Dec 2005 05:29:00 -0500, David and Brenda Holman wrote:
>  
>
>>Mike and all,
>>
>>The 120 Hz you are seeing could very easily come from fluorescent
>>lights.  This is a very common problem.
>>
>>David, KE3HF
>>
>>
>>
>>
>>kd7ts wrote:
>>
>>    
>>
>>>hello interested parties...
>>>
>>>When I displayed the Lees wave files on a waterfall I saw 120 HZ
>>>signals nicely spaced, and easily observed.
>>>
>>>Thinking back to A.C. power supply theory, we have different ripple
>>>
>>>frequencies with different rectifier schemes, half wave, full wave
>>>and
>>>bridge. I'm a little hazy on this stuff, but would a magnetic field
>>>
>>>generated from 60 CPS mains have a 120 CPS effect ? Maybe there is
>>>a
>>>way to generate a 120 HZ magnetic field ?
>>>
>>>I just tried holding my Weller solder gun next to the DSP-10, and I
>>>
>>>see spurs every 60 cycles, not just every 120, when I pull the
>>>trigger. ( I was watching a signal from my generator at 144.000600)
>>>
>>>I wish I had an answer, but instead, more questions..
>>>
>>>
>>>Mike KD7TS
>>>
>>>
>>>
>>>
>>>_______________________________________________
>>>DSP-10 mailing list
>>>DSP-10 at mailman.qth.net
>>>http://mailman.qth.net/mailman/listinfo/dsp-10
>>>
>>>      
>>>
>
>
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>  
>

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