[time-nuts] Wenzel oscillator - L1 value?
Philip Pemberton
lists at philpem.me.uk
Sun May 4 11:30:43 UTC 2014
On 24/04/14 23:30, Bob Camp wrote:
> There is no difference at all between a 32 pf series crystal and a 32
> pf parallel crystal. They both resonate with a 32 pf load and operate
> at exactly the same frequency into that load. Your crystals will work
> fine with that circuit.
That's good to know.
I'm actually testing with one of these crystals:
http://uk.farnell.com/multicomp/hc49u-10-20-50-60-30-atf/crystal-hc-49-u-10-0mhz/dp/1666972
On the basis that they're cheap and I don't want to ruin one of my OCXO
crystals. Said OCXO crystals came from QuartSLab, with the following
specification:
Crystal Frequency: 10.00000 MHz, Fundamental Mode
Holder Type: HC-49/U
Circuit Conditions: Parallel Resonant
Load Capacitance: 33 pF
Oven Temperature: 50 Celsius
Those things cost £17 each and had a 20-day lead time last time I bought
one, so I'm keen to avoid damaging them!
They're probably not fantastic compared to a 10811's SC-cut part, but
this is only intended to be a learning experience. I'd consider it "good
enough" if it could hold its own against my LPRO.
The invoice calls them out as "10.00000 HC49 S03F1" -- I'm honestly not
certain what "S03F1" indicates.
> The big claim to fame of the circuit shown is that you can get a nice
> looking sine wave out of it at a pretty big peak to peak voltage.
> It’s not bad for phase noise, but it’s also not the “super quiet”
> that you would expect if you paid kilo bucks for a Wenzel OCXO.
I'll probably be mating it to a 50-ohm driver of some description, then.
That's a job for later, I need to make the oscillator work first :)
For now I just need to keep it under +24dBm into 50R (limit of my
spectrum analyser), preferably less than +13dBm (1V over 50R).
Thanks,
--
Phil.
lists at philpem.me.uk
http://www.philpem.me.uk/
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