[time-nuts] Wenzel oscillator - L1 value?

Tom Knox actast at hotmail.com
Wed Apr 23 21:06:41 EDT 2014


Does adding these filter elements lower Q or affect Phase Noise?
Thanks;

Thomas Knox



> From: lists at rtty.us
> Date: Wed, 23 Apr 2014 17:47:26 -0400
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Wenzel oscillator - L1 value?
> 
> 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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