Atlanticon 2005
The Crystalizer Bakeoff
Atlanticon 2005
The Crystalizer Bakeoff
There
were 13+ good entries in the bakeoff. They
ranged from a sophisticated microcontroller-operated, compensated oscillator to
several well-insulated devices (a delaying action at best), to several “bare
board” Crystalizers. Ingenuity
was the rule of the day.
The
test itself consisted of using a frequency counter and a receiver based on the
N8ERO WWWV calibration receiver to measure the frequency of each oscillator
entry. Contestants were allowed to
“tweak” their items on frequency at room temperature.
The test setup monitored frequency as a hair dryer was used to expose the
units tested to an elevated temperature for several minutes.
The
top entry was by Steve, N1NB who brought a digitally-compensated Crystalizer using
the Micro908. A thermistor,
thermally attached to the Crystalizer board, fed the Micro908. It was pre-calibrated to feed back a DC signal at each
temperature to tune the oscillator on frequency. Frequency held to within 1 Hertz.
Steve
also had a “gag” entry with a Crystalizer that was temperature-stabilized by
a large aluminum block with chilled water flowing through it.
This held frequency quite well and would have done so until the ice
melted!
In
second place was the entry by Charles, AA3WS. It was
a very well-insulated case which delayed the effects of external temperature
changes.
In
third place was a Crystalizer that Jim, K2SZ mounted in a sealed, insulated case with a Peltier-effect
heater/cooler. There was no closed
loop feedback but there was enough thermal mass to the assembly such that
prolonged periods of added heat did not grossly change the oscillator frequency.
The
fourth place entry was by Carl, AA2JZ
and was another example of a well-insulated case.
Several minutes of heating resulted only in minimal temperature change,
though given enough time *that* would change.
The fifth place Crystalizer was built by Hank, K8DD. It was the best in class of uncompensated Crystalizers that did not have insulated cases. Apparently the stack up of a good crystal and component temperature coefficients kept his frequency within less than 30 Hertz even when well-heated by the hair dryer!
Be sure to take a look through all the photos of the Saturday evening festivities to see some good shots of the contestants' entries. Congratulations to everyone who participated ... there were many winners for this contest!
72/73,
Joe Everhart, N2CX
