[Lowfer] trimmer for pierce oscillator

[Douglas D. Williams]

Sure. I'll do one better and give you the entire article. I hope I don't get
in trouble for posting a thirty year old article...

http://i81.photobucket.com/albums/j231/Goranothos/converter1.jpg

http://i81.photobucket.com/albums/j231/Goranothos/converter2.jpg

http://i81.photobucket.com/albums/j231/Goranothos/converter3.jpg

http://i81.photobucket.com/albums/j231/Goranothos/converter4.jpg


and a picture of the complete unit:


http://i81.photobucket.com/albums/j231/Goranothos/converter.jpg


Thanks for the advice from those who responded. I will attempt to implement
some of it to get the crystal exactly on frequency. 

-Doug KB4OER



-----Original Message-----
From: lowfer-bounces at mailman.qth.net [mailto:lowfer-bounces at mailman.qth.net]
On Behalf Of WE0H
Sent: Friday, May 25, 2007 12:24 PM
To: Discussion of the Lowfer (US, European, & UK) and MedFer bands
Subject: Re: [Lowfer] trimmer for pierce oscillator

Hi Doug,

Could you scan the complete schematic?

Many thanks,
Mike
WE0H

Douglas D. Williams wrote:
> Years ago I built an LF converter from a design by Doug DeMaw and Jay
> Rusgrove that appeared in the June, 1977 issue of QST. It has proven to be
> an excellent design, outperforming two different commercial converters
that
> I have tried out. 
>
> The local oscillator circuit in the converter is a simple Pierce
oscillator
> designed around a 2N2222A transistor and a 1.7 MHz crystal. The crystal I
> have is 290 Hz high and I would like to add a trimmer capacitor to be able
> to adjust the frequency dead on so I don't have to do any mental
gymnastics
> when trying to tune a certain frequency. 
>
> Here is a link to the schematic of the oscillator circuit:
>
> http://i81.photobucket.com/albums/j231/Goranothos/oscillator.jpg
>
>
> My question is where should I add the trimmer capacitor and what value
> should I use? 
>
> Thanks in advance for any help.
>
> -Doug KB4OER
>   
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