[Elecraft] 10 MHz external reference - GPSDO

[David Anderson]

Hi Gary,

Because the K3 only -frequency- locks the frequency to within about 2Hz you won't notice any difference between them. Similarly because the K3 TCXO isn't -phase- locked to the external reference any phase noise on the reference won't affect low phase noise of the synthesiser in the K3.

So buying a kilobuck reference isn't going to gain you anything at all. 

The BG7TBL or the Leo Bodnar unit would be my choice. (I have both here and a Z3801A) . The Leo Bodnar being a nice low power consumption unit, and a lot more versatile than just a 10 MHz GPSDO. It has many other uses around the shack, covering up to 800 MHz.


73 from David GM4JJJ

> On 11 Mar 2016, at 12:53, Gary Smith <Gary at ka1j.com> wrote:
> 
> 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
>> out the Reverse Beacon Network at
>> <http://reversebeacon.net>, now
>> 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
> 
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