[Elecraft] 10 MHz external reference - GPSDO

[Gary Smith]

I appreciate the replies to my question about sourcing a 10 MHz 
external reference for my K3s. I didn't realize I needed more than 
the K3EXREF to gain this accuracy and thanks to these replies, I now 
better understand what will and what will not work. While I would 
prefer to be able to buy a satisfactory GPSDO or kit from Elecraft, 
it isn't an option at this time and not knowing if one is on the 
Horizon, I must look elsewhere to find one. 

What makes it a more difficult choice is understanding what values 
are sufficient and what is excess; some of these devices are in the 4 
figures and some used are less than $40. I was about to buy a $40 
used TCVCXO but learned they need to be recalibrated to maintain 
their precision and I having no equipment to do this, one of the more 
expensive options apparently is a better solution.

Apparently the low cost GPSDO are an affordable way to go for long 
term accuracy but which one to get? Some apparently have jitter from 
poorly isolated interference due to the proximity of their 1pps 
Square wave functions but is that jitter something to affect their 
function as a frequency standard for the K3/K3s, I have no idea. Is 
there an advantage in accuracy by using the GPSDO linked below over 
the BG7TBL versions from China? $226 & needing antenna and power 
supply for low jitter vs $150 for everything but with higher jitter? 
Is a square wave output as useful as a sine wave, both are available 
in the BG7TBL versions. For an external reference function with the 
radio, what is excess? I have no idea.

Apparently the components in the BG7TBL versions change due to their 
supply of surplus components; the versions are the manufacturing 
date, and not all work identically because of this. But does it 
matter, is the least desirable GPSDO still adequate to do this job 
properly? Engineering is not my field and there's a lot to sift 
through in reading peoples discussions and opinions when most of the 
comments are not directed to effectiveness with the K3/K3s.

There are other options available but apparently the prices have gone 
up recently and some once viable options are now not available or 
highly priced, even when used. If Elecraft is not going to make an 
option available for purchase, what would probably be helpful would 
be a listing here or on someone's page, of what kind of affordable 
units are ideal for the 10 MHz reference source and what is 
un-necessary overkill.

Thanks again for the replies, its always fun to learn new things.

73,

Gary
KA1J


> Take a look at this GPSDO 
> <http://www.force12inc.com/products/gps-locked-precision-frequency-reference-low-jitter-gps-clock-450-hz-to-800-mhz-output.html>. 
> Needs 13-15 VDC and a powered GPS antenna, but it is plug and playon any 
> frequency from 450 KHz to 800 MHz, with software-adjustable output level.
> 
> 73, Pete N4ZR
> Download the new N1MM Logger+ at
> <http://N1MM.hamdocs.com>. Check
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> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
> 
> On 3/9/2016 12:37 PM, Gary Smith wrote:
> > I ordered the K3EXREF and thought it was the oscillator itself which
> > would provide the external signal source to the K3s. I thought this
> > was all I was going to need but I see now that is not the case.
> > Looking on the Elecraft order page, they don't sell a reference
> > source.
> >
> > What external 10-MHz reference signal source might I find get that is
> > not terribly expensive that will do the proper job and allow me to
> > get this working?
> >
> > Thanks & 73,
> >
> > Gary
> > KA1J