[Elecraft] XG3 Quesiton

[Phil Hystad]

Thanks for the quick answer.  This may be a winter project.

PEH's iPad

On Oct 25, 2012, at 10:28 AM, Wayne Burdick <n6kr at elecraft.com> wrote:

> A crystal oscillator generally produces something approaching a sinewave, with varying degrees of harmonic distortion depending on how much output power the designer was trying to get out of it.
> 
> The XG3's signal is quite stable as it is derived from a crystal oscillator. But its output will be very close to a square wave, and if the RX/TX stages that follow don't have a lot of filtering of their own, you'd be better off filtering the XG3's signal with a simple 5-element low-pass filter. The ARRL Handbook has examples.
> 
> A crystal oscillator will have one more advantage over an XG3, usually: lower phase noise. The XG3's phase noise is a relatively constant -105 dBc/Hz at all offsets, whereas a crystal oscillator might be down to -140 dBc/Hz at 1 kHz and -150 to -160 at 10 kHz.
> 
> The practical implication of this is that the XG3 should not be used as the local oscillator for a high-power station (100 W+). That -105 dBc/Hz figure for phase noise would translate to wideband noise on key-down if you have hams as neighbors. The phase noise is less of a concern at QRP levels.
> 
> 73,
> Wayne
> N6KR
> 
> 
> On Oct 25, 2012, at 10:17 AM, Phil Hystad wrote:
> 
>> Follow on question...
>> 
>> What type of signal (wave?) does a crystal, as used in old rigs like the Eico 720, produce?  I am thinking that the oscillator of something like in the 720, would clean up the output of the XG3 a little bit.  I was actually thinking of using the XG3 as a crystal replacement type of VFO in my Eico 720 but I never even got around to think too much about it (probably because I was having too much fun putting together Elecraft kits and operating them).
>> 
>> PEH's iPad
>> K7PEH
>> 
>> On Oct 25, 2012, at 10:00 AM, Wayne Burdick <n6kr at elecraft.com> wrote:
>> 
>>> Lee Buller wrote:
>>> 
>>>> Does the XG3 have the stability and output power to be used as a VFO
>>>> for older
>>>> (1950-60s) CW and Phone rigs like the T-50, DX-40, etc.?
>>> 
>>> Yes, with appropriate level conversion, and possible filtering (the
>>> output of the XG3 is closer to a squarewave than a sinewave, so a low-
>>> pass filter may be needed).
>>> 
>>> 
>>>> 
>>>> Are there software programs that have been written that allows "VFO"
>>>> operation?
>>> 
>>> You can use XG3 Utility for this, or write your own app pretty easily.
>>> The full command set is documented in the manual.
>>> 
>>> Wayne
>>> 
>>> 
>>>> 
>>>> Lee - K0WA
>>>> 
>>>> 
>>>> 
>>>> In our day and age it seems that Common Sense is in short supply.
>>>> If you don't
>>>> have any Common Sense - get some Common Sense and use it.  If you
>>>> can't find any
>>>> Common Sense, ask for help from somebody who has some Common Sense.
>>>> Is Common
>>>> Sense divine?
>>>> 
>>>> Common Sense is the image of the Creator expressing revealed truth
>>>> in my mind.
>>>> -  John W. (Kansas)
>>>> 
>>>> Never interfere with anything that isn't bothering you.
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