Clock selection

abzug

Disabled Account
2006-01-18 8:08 pm
whereisit
Various clocks like the Tent, Elso Kwak, etc. are known, but I'd rather not spend much on boutique clocks and buy ones used in industry (also, I couldn't even figure out where to buy a Kwak clock).

Jitter given in spec sheets is useless unless the offset frequency from which phase noise was integrated is known. On the few manufacturers that provide detailed phase noise data, I notice two kinds of clocks: ovenized oscillators which are designed to have phase noise low even starting from 1 Hz or less away from the fundamental and are extremely expensive, and others which have data usually from 1 kHz or at best 100 Hz.

For audio applications, something in between would seem to be needed, and about 10 Hz offset starts being important. The ovenized clocks are overkill (and too expensive), whereas the others I mentioned are probably not sufficient (and I've failed to get more data on them despite having contacted a couple of manufacturers--the response is either we don't have that data, or no reply at all in the case of one).

So, any recommendations of either specific oscillators where such data would be provided, or manufacturers with good customer service?
 
I agree that a good OCXO would be the best solution. The next best choice could be a good TCXO, I chose that way. I bought a Motorola 1 MHz TCXO on eBay and replaced the internal 4 MHz crystal with a 16.9344 MHz crystal. The oscillator itself is a 2-transistor Colpitts circuit. There is a divide-by-four circuit at the output. The whole unit is in a big flat metal can, fixed by four screws and there is a frequency adjustment hole. It is about 6 x 6 x 2 cm. I also had to replace one of the feedback capacitors to meke the higher frequency crystal oscillate in the circuit. Fortunately this unit came with a circuit diagram. Now it is serving as a master clock in my Marantz CD-84 player...
 

jkeny

Banned
2007-02-06 12:43 am
Dublin

jkeny

Banned
2007-02-06 12:43 am
Dublin
I see another site http://diykits.com.hk/ with low jitter clocks for $20 but no specs given. These clocks seem to have a screw suggesting some form of adjustment! What would this be used for?

In both of the sites they seem to use the same PCB with double 317 regulator board & a clock board suspended by bands!
 

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oshifis said:
I agree that a good OCXO would be the best solution. The next best choice could be a good TCXO, I chose that way. I bought a Motorola 1 MHz TCXO on eBay and replaced the internal 4 MHz crystal with a 16.9344 MHz crystal. The oscillator itself is a 2-transistor Colpitts circuit. There is a divide-by-four circuit at the output. The whole unit is in a big flat metal can, fixed by four screws and there is a frequency adjustment hole. It is about 6 x 6 x 2 cm. I also had to replace one of the feedback capacitors to meke the higher frequency crystal oscillate in the circuit. Fortunately this unit came with a circuit diagram. Now it is serving as a master clock in my Marantz CD-84 player...

Hmm...
Somebody said that the OCXO would create noise due to the internal circuits.

Also, sometimes is possible to find rubidium XO from china...

I agree that a high-perf TCXO would be the most viable solution.
I'd like some input on the parameters to look for in telcom/military products:

-ppm
-jitter (some parts are declared "low jitter", some have value, lower the better of course)
-frequency. Assuming that i can choose whatever freq to use in my dac (i'm NOT modding an existing unit), higher is better? Standards are 12 and 16Mhz... but what would be better?

*tired and confused*