[DSP-10] CW transmit has a raspy sound

[Bob Larkin]

I posted the second picture of the 126 MHz oscillator, free-running, at
http://www.proaxis.com/~boblark/127mz2.jpg
You can see that it has picked up some 5 kHz modulation , but otherwise is 
clean.  The 5 kHz is likely stray pickup from the PLL IC that is still 
running. The output of the phase detector is removed by a wire across C113. 
The frequency at this voltage has moved down to about 123 MHz.

73, Bob W7PUA

At 05:52 PM 3/28/2006 -0800, you wrote:
>One more test---I just made the 126 MHz osc free run by a short across 
>C113. It looked reasonably clean at 5 kHz/div and 1kHz BW. Much, much 
>cleaner than what I see in your SA shot.. Later, I will post it for reference.
>
>Good luck,
>  Bob
>
>At 05:36 PM 3/28/2006 -0800, you wrote:
>>Hi Lee,
>>
>>I agree, something is quite wrong!!
>>
>>I dropped a loop near the 127 MHz Osc ( I moved up to get roughly the 
>>tuning voltage you have) and snapped a picture of the spectrum analyzer:
>>http://www.proaxis.com/~boblark/127mz1.jpg
>>
>>This was done with the BW I had available, 100 Hz, as I don't have 300 
>>Hz.  But  BW=1 kHz looks clean also. There was nothing to see outside of 
>>2 kHz/div so I
>>
>>Maybe loop filter components? Possibly, but not likely the PLL IC.  Maybe 
>>someone else has ideas.
>>
>>Also, the spectrum to the right  in the unlocked pix seems strange. How 
>>did you achieve "unlock?" Maybe this is the residual on the phase 
>>detector output.
>>
>>I will pursue this further, after dinner.
>>
>>73,.  Bob W7PUA
>>
>>At 04:43 PM 3/28/2006 -0500, you wrote:
>>>I have been playing around some with an HP 141T spectrum analyzer I just 
>>>purchased and have been looking at the local oscillators.  While the 
>>>19MHz osc looks fairly clean, the 124MHz osc does not. As a mater of 
>>>fact, it is pretty bad in my opinion.  I don't know if anyone else has 
>>>had the opportunity to look at theirs but I've put up a web page on my 
>>>web site showing what I've found.
>>>
>>>When taking the measurements, I've removed the coax jumpers from the 
>>>outputs of the oscillators and used a pigtail coax with an SMA connector 
>>>to get the signals to the analyzer.
>>>
>>>The URL is http://www.aa1yn.com/dsp-10/spec_ana/ and the images are 
>>>linked to medium resolution images.
>>>
>>>Any thoughts? Any questions? Any ideas?
>>>
>>>
>>>Lee Scott - AA1YN http://www.aa1yn.com
>>>Home of the VHF & Up Register http://www.aa1yn.com/vhf
>>>Home of the VHF Talk chatroom http://vhftalk.aa1yn.com
>>>Hooksett, NH
>>>FN43gc52
>>>
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>>
>>
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