[eagle] Re: The DS4000 Digital Controlled TCXO

Jim Sanford wb4gcs at amsat.org
Tue Jul 3 20:07:41 PDT 2007

I can't imagine it NOT being a problem.

For the sake of completeness, let's assume that it IS, and solve it.

Thanks for all your hard work.

wb4gcs at amsat.org

Juan Rivera wrote:

>Hi Bill,
>Aren't all these tools neat?  I though you'd like the audio!
>I'm thinking that the uplink guys are going to have to weigh in and tell us
>if these jumps are a problem or not for data.  I'd think that they would be
>for demodulating data and a major annoyance for SSB.  It's the sort if
>subtle stuff that I didn't notice at first.  I'm sure there are a few more
>surprises waiting to be discovered.
>I'm curious about the beat since the two oscillators produced IF outputs
>that were fairly far apart and yet the beat seems to be around 1 Hz.  I
>guess I could try to sniff the internal oscillator to see exactly where it
>really is.
>-----Original Message-----
>From: Bill Ress [mailto:bill at hsmicrowave.com] 
>Sent: Tuesday, July 03, 2007 6:49 PM
>To: juan-rivera at sbcglobal.net
>Cc: eagle at amsat.org
>Subject: The DS4000 Digital Controlled TCXO
>Hi Juan,
>The audio is a fantastic addition to your super analysis regime. Just 
>really fine work!!
>I've already addressed the issue of the two 10 MHz oscillators beating 
>as heard in clip #1.
>Now what you hear in the second audio clip doesn't surprise me. Just 
>another reason why I remain digitally challenged and analog biased.
>The DS4000 is a "digitally" corrected voltage controlled oscillator. I 
>believe what you are hearing is the frequency being corrected in finite 
>digital steps. An analog temperature corrected VCO will not do this. The 
>correction will be continuous and smooth. The key advantage of the 
>"digitally" corrected VCO is the ability to "remotely" correct the 
>frequency with a digital input. I would submit, that feature is not 
>needed for our application.
>The "analog" TCVCXO used in the S2 concept converter uses a low cost 
>device (available from several suppliers) and offers +/- 1 PPM stability 
>over temperature (-40 to 85 C).
>Regards...Bill - N6GHz
>Juan Rivera wrote:
>>I should have gone to work today but I ended up working on the 70 cm 
>>Receiver all day instead. Today marks a milestone for me -- my first 
>>use of audio files. You'll find two in my write up if you click HERE 
>><http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Stability.htm>. I 
>>think they work much better than descriptions and graphs. Now you can 
>>hear what I'm talking about...
>>Have a great 4th! I plan to do a temperature run on the receiver 
>>tomorrow to celebrate! Let's see what that internal oscillator does 
>>when it's not at room temperature!
>>P.S. to OSCAR guys... If you have time come on over and help me run 
>>this test. I'll probably start early to beat the heat. If you've never 
>>been gassed by CO2 before, now is your chance!
>>Juan - WA6HTP
>Via the Eagle mailing list courtesy of AMSAT-NA
>Eagle at amsat.org
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