[Boatanchors] oscillator waveform

[hwhall at compuserve.com]

Hello!

> Should the waveform from a hetrodyne oscillator in a 
> receiver front-end be a  clean sine wave? Does it matter 
> if it is a skewed or not symmetrical waveform?
> I'm working on a receiver which seems (to me) to have a 
> lot of birdies or
> tweets and I'm wondering if that waveform could be 
> significant contributing factor.
 A waveform that is not a clean sine will be composed of some, possibly many, other frequencies of different amplitudes. If that distorted signal is getting into the converter stage, then unpredictable odd signals can  be output from the converter. If I were working on that, I'd see if I couldn't clean up the local oscillator output.  But beware that what you see (I assume you have a 'scope) may not be the true situation. There is a possibility the scope display is not accuratly representing the signal, or that the connection of the scope to the oscillator is affecting the oscillator.

Wayne'
WB4OGM

 

-----Original Message-----
From: Richard Knoppow <1oldlens1 at ix.netcom.com>
To: Paul Kraemer <elespe at lisco.com>; boatanchors <boatanchors at qth.net>
Sent: Sun, Dec 12, 2010 3:52 pm
Subject: Re: [Boatanchors] oscillator waveform



----- Original Message ----- 
From: "Paul Kraemer" <elespe at lisco.com>
To: <boatanchors at qth.net>
Sent: Sunday, December 12, 2010 2:05 PM
Subject: [Boatanchors] oscillator waveform


>A tecnical question for the group:
> Should the waveform from a hetrodyne oscillator in a 
> receiver front-end be a
> clean sine wave? Does it matter if it is a skewed or not 
> symmetrical
> waveform?
> I'm working on a receiver which seems (to me) to have a 
> lot of birdies or
> tweets and I'm wondering if that waveform could be 
> significant contributing
> factor.
> Alignment of the xtal oscillator "by the book" looking for 
> maximum voltage
> produces somewhat distorted waveform.
> A slight mis-tuning while observing the scope to make the 
> waveform more pure
> is possible on some bands but not all.
> Paul K0UYA
>
    What model of receiver? Most LO's are designed to put 
out a reasonably clean waveform.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com 

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