[time-nuts] Wenzel oscillator - L1 value?

Bob Camp lists at rtty.us
Wed Apr 23 21:38:29 EDT 2014


HI

The circuit they show is not very low phase noise, so adding stuff is not going to degrade it much. It will lower Q, but again, it’s not really Q limited over most of the range. 

The real issue with the circuit is that it has lousy load isolation. 

Bob

On Apr 23, 2014, at 9:06 PM, Tom Knox <actast at hotmail.com> wrote:

> 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/
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
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>>> and follow the instructions there.
>> 
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