Model 2350 System  SPECIFICATION  gether (Limit would be 10 rack panels per com-
puter.)  The rack panel is 23.5" (59.7 cm) wide and  7.0"  (17.4  cm)  high.  The power regulators for each oscillator are  mounted  behind  the  panel  and  are  properly  en-  closed for safety.            This  configuration  provides  a  stable  envi-
ronment  of  fixturing,  time  of  measurement  and
supply  voltage  (room  ambient  temperature  may
vary) to perform oscillator aging and measure this
aging. To simplify expansion, the system is sup-
plied  as  self-contained  rack  panels  that  hold  5
personality  cards  (20  oscillators).  These  self-
contained rack panels can be "daisy chained" to-  Basic equipment needed (can be optionally expanded to from 100 OCXOs to 200 OCXOs on the same
computer,counterandDMM):  Qty     Description  1  ControllingPCusinWindows95OSR2  1  HP LaserJet 4P  1  PRAOCXORoomTemperatureAgingTestSystem  HP 34401 DMM
HP53181 or HP53132 Counter -or- Guide Technology GT654 or GT-200 counter
Computerparallelcontroloutput
Allneededcabling
Systemsoftware  1  Agingrackassemblyfor100OCXOs  5 rack panel assemblies - each assembly holds 20 OCXOs.  Adding an additional Aging rack assembly for 100 OCXOs (Total system for 200 OCXOs)
{OPTIONAL}  5 rack panel assemblies - each assembly holds 20 OCXOs.
Overallchassistosupporttherackpanels  25Personalitycardsperchassis  HARDWARE CONFIGURATION  NOTE: PRA Inc. reserves the right to make changes to the product contained in this data sheet in order to improve the design or performance
and to supply the best possible product. PRA Inc. reserves the right to make these changes without notice.  Revised9/1/02

           These step down limited supplies are sup-
plied  with  adequate  heat  sinks  to  withstand  an
indefinite shorted output. The design of the supply
is such that any failure of the IC and its internal
switch transistor will cause the position to lose
power and not be powered with an unlimited and
uncontrolled voltage. A flyback switching regula-
tor is used to provide this fail safe feature.            If the oscillators being tested have additional
power supply voltage needs; these voltages will be
derived on the oscillator personality cards. Simple  integrated circuit (IC) 3 terminal regulators could
supply low current positive voltages. If negative
voltages  are  needed  or  higher  current  positive
voltages, simple IC switching regulators can be
supplied on the personality cards. The possible
power supply options and voltages are only limited
by size of the personality card and the designers
creativity.            A chamber mounted version of this system
(Model 2201) is available to permit checking the
temperature stability of the OCXOs.  PERSONALITYCARDS  which oscillator that potentiometer controls. The
potentiometers will be screw driver adjustable.             The personality card also has a connector on
the card for connecting power. This is a simple
PCB mount connector that can be used to keep
power  applied  to  the  4  oscillators  if  the  card  is
withdrawn from the edge connector. Any one or
all  4  of  the  oscillators  can  be  changed  and  the
personality card reinserted into the aging fixture.             Each oscillator under test is mounted on a
personality card or attached to a cable that termi-
nates  on  the  personality  card.  This  personality
card has gold plated edge card fingers.             Each personality card optionally will have
along  the  front  edge,  4  each  10  or  more  turn
potentiometers  that  supply  bias  to  the  fine  fre-
quency adjust control on the oscillators under test.
The  potentiometers  will  be  labeled  to  indicate             The system treats each individual oscillator
as a separate entity. The system is programmed to
make  tests  on  each  oscillator  at  a  user  defined
timing. The data is accumulated (frequency and
Icc) versus time. The system can curve fit the data
to project the aging or simply be compared against
user  input  limits.  The  aging  data  can  also  be
plotted.             An oscillator can be taken off the system or
added  to  the  aging  group  at  any  time.  Simple
screen prompts let the user complete a test or begin  DATA RECORDING  a  test  on  a  new  oscillator.  The  system  permits
automatic restart if there is a power outage. The
data can be printed at anytime for any oscillator.             The  system  also  operates  on  a  Novell  or
Artisoft Lantastic (peer to peer) type network to
permit data printing and reduction on other com-
puters.             PRA  has  MicroSoft  Windows  3.1  based
data analyses and plotting programs provided with
the system.

 SYSTEMFEATURES  supply  has  been  chosen  to  power  a  group  of
oscillators. If this main power supply was con-
nected directly to the oscillators under test, any
accidental  short  circuit  would  allow  up  to  20
amperes to flow. This amount of current could
cause damage to connectors, would cause over
heating,  damage  the  oscillator  under  test  and
possibly cause arcing that could be hazardous to
the system operator.           This system places a programmable, current
limited supply (Only programmable to off, nomi-
nal, ±5% of nominal and ±10% of nominal) in  series with each oscillator under test. The absolute
maximum current per oscillator is limited to less
than 1.5 Amps. A sense resistor is included with
each programmable supply so supply current can
be  monitored  for  the  oscillator  under  test.  The
sense resistor permits measuring of oven start up
current and static or stable OCXO power require-
ments.           The Model 2350 system is designed to test
and  age  5  to  30  volt  oscillators.  The  system
permits  each  oscillator  under  test  to  have  the
supplied voltage at nominal, ±5% of nominal and
±10% of nominal. (The oscillators operating at
30 volts will not be permitted to be operated at
+5% and +10% levels.)           The  maximum  continuous  supply  current
per oscillator is 800mA. The system can deliver up
to 1.2 Amps per oscillator for up to 5 minutes.           To achieve the ultimate frequency accuracy/
stability from the measurements, a 10 MHz fre-  quency precision reference standard must be con-
nected to the system’s counter that is stable to
better than 0.01ppb (part per billion) and be jitter
free.  The oscillator under test requirements present  several challenging problems. An ovenized oscil-
lator can typically draw over 1 ampere or up to 4
amperes per personality card. To achieve reason-
able  costs,  a  very  efficient  20  ampere  power

  Model 2350 Ovenized Crystal Oscillator Aging System  OCXOs mounted on Personality Cards are powered/operating and  the frequency change versus time is measured.                    Frequency resolution to 0.1 ppb
Power Supply current to the OCXO can be measured Testing  times,  resolution and number  of  readings  per  day
are  user  programmable  for
each position in the system. Each  position  can  have  a
unique supply voltage Each position's supplied volt-
age is computer controlled Frequency  range  100Hz  to
over  500MHz The OCXOs are mounted on
personality  cards 4 each OCXOs per personality card