K3EXREF Query

[Geoffrey Downs]

Ed, you restate the problem and a simple solution but quite apart from the
cost (which is trivial or not depending on your circumstances) we should
all, in my view, be trying not to use energy unnecessarily in the interests
of our grandchildren. There is also a potential fire risk with a unit that
is running permanently.

A preferable solution would be some means for the K3 to ignore the external
reference until it has stabilised after switch-on. This issue has so far
deterred me from buying a K3EXREF but it's not a big issue because the K3 is
so stable and accurate and Ref Cal needs to be checked only occasionally. In
fact I presume that once the external standard has set the K3  through the
EXREF the K3 stays put when the reference is switched off so you could leave
your reference off most of the time and only put it on when you are not
planning to use the K3 for half an hour or so and want to check the
calibration.

73

Geoff
G3UCK

-----Original Message-----
From: Edward R Cole
Sent: Tuesday, October 14, 2014 10:47 PM
To: [hidden email]
Subject: Re: [Elecraft] K3EXREF Query

David,

10w is 7.3 kwH/month.  I would doubt that is a large expense, even in
GB.  Locally, its about 8 cents/kwH but in the bush it might be as
high as a couple dollars since diesel fuel for the generators costs
are huge (local diesel is $4.10).  I know it would require conversion
to liters and all that to come up with equivalent costs, but most
households run hundreds of kwh/mo.  Leave your TV plugged in but
turned off and it still consumes about 50w.  I have plug strip to
remove ac from all my home TV systems when not in use.  I leave power
to the satellite receiver as it keeps the LNB powered and stable
(Otherwise it takes 5-10 minutes to acquire signal and download data
at startup).

Simple solution is to leave the reference oscillator running
continually.  The K3 TCXO-3 will still drift on power up but this is
compensated by EXREF every 4-seconds so frequency stability is held
to better than 0.1 ppm.  I measured +/- 2 Hz at 28-MHz on my K3.  But
if you watch the REF*CAL frequency you will note it incrementing from
49.380.000 to something like 49.380.080 in several minutes and then
settle down near that value (indicating start-up drift has stopped).

By not running your reference full time you will have to wait 15 to
30 minutes for it to fully warm up.  I also have a rubidium but run
it only for precise frequency calibration of the OCXO couple times
per year.  My mw counter internal TCXO is always in agreement with
the Rb so I do not bother for routine frequency checks.  The rb is
only +/- 5 E-11 so not as good as GPS but good enough for my use.

73, Ed - KL7UW
-------------

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[Bob-270]

Maybe my concept is wrong but I do not see the need to leave a GPSDO on.  Once
the GPSDO locks to the satellite it is all that is required. I have decent sky
view and it locks up using multiple satellites quite quickly.  So before the K3
has warmed up the GPSDO has locked and I'm locked to it.
The K3 and XCO drift in the GPSDO  are really out of the picture. Using a
Trimble Thunderbolt here.

To me it was overkill in the 1st place. A "want to" rather than a "need to".  
Now that  I have the 10MC reference available I'd like to lock the 2 & 430 XV's
to it.   Wayne and Eric you listening? Might be another product to consider, an
add on kit.

73,
Bob
K2TK  ex KN2TKR (1956) & K2TKR


On 10/15/2014 12:15 PM, Harry Yingst via Elecraft wrote:

> Typically (from my understanding) you leave the TCXO and GPSDO running all the timeI believe the the Rubidium standards have a lamp that wears out in time so some turnthem off to conserve the life of the lamp.
> I leave the Oven in my Counter on all the time to keep it stable.
> I just purchased a GPSDO and plan to leave it on all the time.
>
>
> As for the expense....to me the expense is minimal.
>
>
>
>
>

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[W7CS]

Don't you guys have anything better to do than nit pick over a
negligible warm up drift.  I don't think that you will be planning to
do any ARRL Frequency Measurement Tests, within the first 10 minutes
of your K3 turn on !

I have bought several 10 MHz DOUBLE Oven Controlled Crystal
Oscillators, from off shore surplus dealers.  They are reselling
surplus American or Russian built, high quality devices.   Warm up
drift time to within < 10 cycles (Hz), has been less than 10minutes,
usually about 5.  Some are spec'd of stabilities of 10 to -11th.

With these quality OCXOs, I have not found it necessary to use a Ruby
or GPSD oscillators to provide at least digital communication
required stabilities, even when used to stabilize 10 GHz xvrtr
L.O.s.  The power savings, by using this type of device, is
especially valuable in field operations.  I even have mounted one on
the inside of the blank back panel of my K3/10.

For supplying other devices with your now stable 10 MHz, DEMI has
nice four way 10 MHz signal splitters that even have LP filtering on
each output.

W7CS

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