[time-nuts] Wavecrest DTS-2077 Teardown

[Said Jackson]

Guys,

The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise.

Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve.

Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good..

Bye,
Said

Sent From iPhone

On Aug 20, 2013, at 18:51, Ed Palmer <ed_palmer at sasktel.net> wrote:

> Adrian,
> 
> I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs.  The differences in the noise floor are surprising.  The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077.  The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz.  If I could have, the 1 GHz line might have been lower than it was.
> 
> Ed
> 
> On 8/20/2013 4:42 PM, Adrian wrote:
>> Ed,
>> 
>> thanks for posting!
>> 
>> I'm still looking for a MUX board for my faulty 2077.
>> 
>> Is there anyone using a DTS-207x with TimeLab?
>> 
>> Adrian
>> 
>> 
>> Ed Palmer schrieb:
>>> FYI, I did a teardown on my Wavecrest DTS-2077.  It's posted here:
>>> 
>>> http://www.eevblog.com/forum/testgear/wavecrest-dts-2077-teardown
>>> 
>>> Ed
> 
> <DTS-2077 Noise Floor.png>
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