[time-nuts] The 5MHz Sweet Spot

[Magnus Danielson]

Bert,

On 11/03/2013 11:51 PM, EWKehren at aol.com wrote:
> We are looking at room temperature 5 and 10 MHz XO's for cleaning up Rb and 
>  DDS. Filter time 1 to 20 seconds and thermal mass to keep temperature 
> influence  low. Hard to find XO's, so what we are testing is older TCXO's where 
> we remove  the TC and use the tuning circuit for loop control. Any 
> suggestions? Maybe  slightly off subject but the experts are here.
> Thanks  Bert Kehren

Assuming we don't go very upscale in OCXO/DOCXO land in size, power and
cost, the oscillators that best handles thermal stress in room
temperature is either those with thermal mass surrounding the crystal
(MicroCrystal and Oscilloquartz) or those where an additional shielding
(Vectron has a bunch of them now). Although AT-cut, they cut the throat
with competing SC-cut as far as I have seen in that package and cost.

I picked up a few of the MicroCrystal ones from ebay. They have that
extra weight (from the FR4 case surrounding the crystal) that none of
the other DIL14 I've seen has. You can feel the difference as you hold
it in your hand. It also consume less power than any of the competition
OCXOs.

I'm sure there might be others in the same range.

You can always put a simple plastic cover over the oscillator if you
need to. Careful about adding thermal mass to OCXOs thought, it may not
always be beneficial to the loop. Measure and verify!

Cheers,
Magnus