Some years back, I was asked to do a study on the current consumption of a
particular style of beverage vending machine. The device had a water tank
which was well insulated and the water was heated by a 3KW heater, to just
below boiling point. The client wanted to know whether there would be a
saving in consumed energy, if the heater was switched off overnight. Careful
study re4vealed that it actually cost more to heat the water from cold than
leave the heater connected permanently, controlled by its thermostat.
There have been numerous papers published to this effect regarding well
insulated domestic heating systems and although there is sometimes a benefit
in reducing the overall temperature when the building is unoccupied, heating
from cold as opposed to leaving the heating running under thermostatic
control, costs more, even over a short period.
The oven used by a stable crystal oscillator is a thermostatically
controlled heating device. Nuff sed! :-)
73,
Alan. G4GNX
-----Original Message-----
From: Edward R Cole
Sent: Tuesday, October 14, 2014 10:47 PM
To: Elecraft@mailman.qth.net
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
-------------
From: David G4DMP <da...@g4dmp.fsnet.co.uk>
To: Mike Harris <mike.har...@horizon.co.fk>
Cc: elecraft@mailman.qth.net
Subject: Re: [Elecraft] K3EXREF Query
Message-ID: <ulj9aoep0tpuf...@g4dmp.fsnet.co.uk>
Content-Type: text/plain;charset=us-ascii
About 10W for the MV89A double oven CXO, when run from a linear 12V
power supply. NOT trivial at today's prices for electricity in Great
Britain.
73 de David G4DMP
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