[time-nuts] Wenzel oscillator - L1 value?

Bob Camp lists at rtty.us
Wed Apr 23 17:47:26 EDT 2014


Hi

Roughly (very roughly) speaking, the series combination of C1, C2, C3 and L1 should equal the load capacitance of the crystal. If there is a varicap, it’s likely in series as well. If the crystal is cut for series, then L1 resonates with the caps in series. 

You can put it on a Spice program and get more accurate results. 

Bob

On Apr 23, 2014, at 10:23 AM, lists at philpem.me.uk wrote:

> Hi,
> I'm currently playing around with crystal oscillators (specifically a homebrew OCXO) and came across the Wenzel low-distortion crystal oscillator:
> http://www.wenzel.com/pdffiles1/pdfs/xtalosc.pdf
> 
> This uses an inductor (L1) to trim the crystal frequency, with the note that a varactor/varicap could be added to allow the frequency to be trimmed electronically.
> 
> Has anyone built one of these oscillators?
> 
> How would you pick a value for L1? I've been reading up on other crystal oscillator types (Colpitts, Clapp,...) and have yet to find anything which uses this style of frequency trimming.
> 
> Where would I add the varactor if I wanted to add EFC? Across C3?
> 
> Thanks.
> -- 
> Phil.
> philpem at philpem.me.uk
> http://www.philpem.me.uk/
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