[eagle] Re: The DS4000 Digital Controlled TCXO

Bill Ress bill at hsmicrowave.com
Tue Jul 3 21:23:32 PDT 2007


Yes indeed, Jim.- a happy and safe Independence Day to you all.

The BBQ's cleaned (well sorta) and ready for tomorrow's hot dogs and 
hamburgers!!!

Regards...Bill - N6GHz

Jim Sanford wrote:
> Juan:
> Based on what I REMEMBER (I'm senile, so take it with a pound of salt) 
> -30 to +50C is plenty at this point.
>
> Thanks for all you're doing. You are producing good data and 
> articulating valid concerns, which I'd rather deal with NOW than ON ORBIT.
>
> Happy Independence Day to all. Please take some time out to enjoy 
> family, celebrate our Nation, honor our Veterans, and spend some time 
> in what my wife calls, "Norman Rockwell America."
> Thanks & very 73,
> Jim
> wb4gcs at amsat.org
>
>
> Juan Rivera wrote:
>>
>> Jim and group,
>>
>> I can’t either, but here’s another area where we need requirements. 
>> How stable does this receiver need to be to satisfy the needs of the 
>> users? Is it driven by the human ear or the ability of a data decoder 
>> to stay locked up? – We need long term / short term requirements?
>>
>> I’m getting set up to do a temperature run tomorrow. I just ran the 
>> radio from +26C to +50C to get an idea what to expect. Here’s what I 
>> found:
>>
>> That missing chunk in the middle is me re-patching my test equipment. 
>> When I saw those saw-tooth’s I wanted to hook the TS-2000 up so I 
>> could listen again. Sure enough they are jumps in frequency just as 
>> the chart shows. Each “tooth” is made of multiple data points so this 
>> is not the +/- 1 digit LSB frequency counter error I mentioned earlier.
>>
>> For this preliminary test I didn’t have a temperature probe inside 
>> the radio so I don’t know how close to +50 it actually got. Tomorrow 
>> I’ll do a much more thorough job and take it down to about -30C. I’m 
>> thinking -30C to +50C. Any other suggestions as to temp extremes?
>>
>> Juan
>>
>> ------------------------------------------------------------------------
>>
>> *From:* Jim Sanford [mailto:wb4gcs at amsat.org]
>> *Sent:* Tuesday, July 03, 2007 8:08 PM
>> *To:* juan-rivera at sbcglobal.net
>> *Cc:* 'Bill Ress'; eagle at amsat.org
>> *Subject:* Re: [eagle] Re: The DS4000 Digital Controlled TCXO
>>
>> Juan:
>> 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.
>>
>> 73,
>> Jim
>> wb4gcs at amsat.org <mailto: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.
>>  
>> 73,
>>  
>> Juan
>>  
>> -----Original Message-----
>> From: Bill Ress [mailto:bill at hsmicrowave.com] 
>> Sent: Tuesday, July 03, 2007 6:49 PM
>> To: juan-rivera at sbcglobal.net <mailto:juan-rivera at sbcglobal.net>
>> Cc: eagle at amsat.org <mailto: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:
>>   
>>> All,
>>>  
>>> 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!
>>>  
>>> 73,
>>>  
>>> Juan - WA6HTP
>>>  
>>>     
>>  
>>  
>>  
>> _______________________________________________
>> Via the Eagle mailing list courtesy of AMSAT-NA
>> Eagle at amsat.org <mailto:Eagle at amsat.org>
>> http://amsat.org/mailman/listinfo/eagle
>>  
>>   



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