text: JL9113 Rev. B CRYSTALS AND OSCILLATORS By Jerry A. Lichter Frequency control devices are generally piezoelectric devices, electromechanical in nature. Mechanical considerations (such as vibration, shock, and handling) of these devices are as important as electrical considerations. Frequency control is required in varied applications from microprocessor timing to radio station transmission. Frequency control devices such as quartz crystals and oscillators are quite fragile. These devices should be handled much more carefully than most other components used in the electronic industry, even though the packaging looks very rugged. Resonators and filters are usually discrete piezoelectric devices. Oscillators incorporate a resonator along with an active device and several discrete components to produce a stand-alone frequency control device. RESONATORS AND FILTERS Resonators and filters use the piezoelectric properties of various materials. The word piezoelectricity means "pressure-electricity". Thus, those devices are electromechanical in nature. Some of the materials which could be used are Rochelle salt, Tourmaline, ceramic, and silicon dioxide. Of these, ceramic and silicon dioxide (quartz) are used almost exclusively. Theory of Operation Monolithic quartz crystals are generally used for two pole filters. These devices are typically "AT" cut and the theory of operation is similar to resonators except that the characteristics are highly dependent on the electrode configuration. Quartz crystal resonators and crystals used in discrete crystal filters have an equivalent circuit as shown in figure 1. Figure 1 The motional capacitance C1 and motional inductance L1 define the series resonance of the device by the equation fs=1/(2ð((L1*C1)½)). This is the point when the magnitude of the motional capacitance impedance equals the motional inductance impedance and thus they cancel out. In many cases the series resonance point can be approximated by finding the point of minimum impedance (this series resonant point is also near the zero phase shift point) and this minimum impedance will be approximately the motional resistance(R1) for these cases. 1 JL9113 Rev. B Series resonance crystals are generally used in crystal filters and resonator circuits which require no phase shift from the crystal in order to oscillate. The effective resistance of the crystal in this type of oscillator circuit is approximately equal to the motional resistance R1. The frequency of operation in this case is the series resonant frequency of the crystal. The shunt capacitance Co (the sum of electrode capacitance Ce and holder capacitance Ch) becomes important in working with frequencies above series resonance. In this region the motional inductance impedance increases and the motional capacitance impedance decreases, resulting in a dominant inductive impedance. When the motional inductance impedance equals the shunt capacitance impedance the anti-resonant point is realized. Crystals intended to operate between series resonance and the anti-resonant point are called "parallel resonant crystals". These crystals are specified by the load capacitance (CL) that they are intended to work into. The equivalent series resistance (the equivalent resistance at the load capacitance specified) of a parallel resonant crystal can be calculated by ESR=R1*((1+Co/CL)²). The shift in frequency from series to the parallel resonant point is given by ªf=(C1/2)*(1/(CL+Co)). ªf*106 would give the answer in ppm. The shift in frequency from one parallel resonant point to another is given by ªf=(C1/2)*((CL2-CL1)/((CL2+Co)*(CL1+Co))). Again ªf*106 would give the answer in ppm. Also note in all the above equations that all capacitances must be in the same units (ie pf). Although it is possible to operate a crystal intended for one application in another, it is important to note the calibration will now be off by the original calibration plus the shift per the above calculation. Also, the temperature drift varies from one CL to another and thus is no longer optimized for the applications. For this reason the idea of a universal crystal for multiple applications is not advisable. Ceramic resonators are similar to quartz resonators with an addition of a shunt resistance Ro due to a high resistance path through the ceramic resonator. Other resonators, by the definition of a resonator, will be similar in nature to the above resonators. The resonant point will be set by the equivalent inductive/capacitive resonance. Characteristics Many different cuts of quartz (different angles of cut from a reference) have been developed for commercial use. AT, BT, and SC cuts are all a thickness shear mode of vibration (see figure 2). FIGURE 2 Thus, these cuts generally cut into round thin disks with the thickness inversely proportional to the frequency. These disks, or blanks, have electrodes placed on each side which are used to make the electrical connection to the crystal. The lowest frequency response is the fundamental mode of the crystal. There are also responses at approximately three times this fundamental frequency, five times, seven times, etc. Those are the third overtone, fifth overtone, seventh overtone, etc. 2 JL9113 Rev. B The AT cut is the most commonly used of these "high frequency" cuts. It is estimated that over 90% of quartz crystals produced today are AT cuts. The AT cut temperature coefficient is a cubic curve (see figure 3). FIGURE 3 The specific shape of the curve and turnover points can be adjusted by small changes in the cut angle. This temperature characteristic gives this cut of crystal versatility for a wide range of applications and temperature ranges. The frequency constant is 1.661 MHz-mm, and is generally limited to approximately 40 MHz on the fundamental mode for small diameter blanks. Using contouring techniques the low end of the AT frequency range is approximately 500 kHz, but is dependent on holder size. Spurious or unwanted responses in the AT cut are typically predictable and can be controlled well using energy trapping techniques. However, spurious margins may need to be traded off with such parameters as pullability (the amount the frequency changes with load capacitance changes). The BT cut, having a frequency constant of 2.536 MHz-mm, can extend the upper frequency range above that of the AT cut to more than 50 MHz. The BT cut is not as widely accepted as the AT cut because of its poorer temperature characteristics in most applications. The temperature curve is a downward parabolic curve. The turnover point can be varied with the cut angle and the curve formula is generally f=-0.040*(To-Ta)² where To is the turnover temperature (EC), Ta is the temperature of interest (EC), and f is in ppm. The SC (stress compensated) cut is similar in design to the AT cut except it is a doubly rotated cut. This means that the angle it is cut out of the quartz bar is rotated about two axis instead of just one from the three reference axis. The frequency constant for the SC cut is 1.797 MHz-mm. Coupled modes are generally worse than the AT cut and crystal resistance is generally higher. Much more care must be used in converting designs from one overtone of operation to another. With proper design considerations the SC cut yields a usable crystal with a very small frequency variation with temperature (approximately +/- one ppm over a ±25 EC. range). 3 JL9113 Rev. B The CT and DT cuts of quartz crystals are both a face shear mode of vibration (see figure 4). FIGURE 4 These two cuts have similar characteristics. The CT cut can generally be designed for frequencies within 300 kHz to 900 kHz and the DT cut from 75 kHz to 800 kHz. Both cuts have a downward parabolic frequency vs. temperature curve. The DT is generally preferred where the frequency allows either because of its lower temperature coefficient (approximately -0.060ppm/EC². for the CT and -0.018ppm/EC². for the DT). The GT cut of quartz crystal is a width-extensional mode of vibration. The GT cut can be designed for frequencies from approximately 100 kHz to 3.0MHz. The temperature coefficient is very nearly zero over the temperature range from -25EC. to +75E C. A temperature variation of ±15EC. on either side of the midpoint of this flat region will not change the frequency more than 0.1 ppm. The E (or 5 deg. x cut) and the MT cuts of quartz crystals are both a longitudinal mode of vibration (see figure 5). FIGURE 5 The E cut can generally be designed in the 50 kHz to 250 kHz range. The E cut is widely used for low frequency crystal filters because it has a low Co/C1 ratio and reasonable low temperature coefficient. In most cases the turnover temperature can be varied from approximately 0 EC. to 50 EC. The MT cut can usually be designed in the 80 kHz to 200 kHz range. The temperature coefficient for the E cut is approximately -0.040ppm/EC² and -0.038ppm/EC² for the MT cut. The H, J, NT, and XY cuts are all flexure modes of vibration. The H, XY, and NT cuts are length-width flexure (see figure 6). FIGURE 6 4 JL9113 Rev. B The J cut is a length-thickness flexure (see figure 7). FIGURE 7 The J plate (cut) has the lowest frequency range (1 kHz to 12 kHz) of these low frequency crystals. The J plate is actually two quartz plates bonded together. The two plates are selected so that one plate's mechanical motion is out of phase from the other for a given electrical field applied. This produces very low frequencies. The H plate (cut) can be designed within a frequency range of approximately 8 kHz to 130 kHz. The H plate crystal is used extensively for wide band filters (ordinarily below the E cut frequency range). The temperature coefficient is linear and varies from about [-8 x 10^-6 /EC to -16 x 10^-6 /EC]. The NT cut can be designed within a frequency range of approximately 8 kHz to 130 kHz. The turnover temperature can be varied from +15 deg. C to +80 deg. C in most cases. The temperature coefficient for the NT cut is approximately -0.036ppm/EC². The XY bar is popular in the 3 kHz to 85 kHz range. Its smaller size than many other low frequency cuts, low impedance, and low Co/C1 ratio make it very popular. Real time clock applications are possibly the biggest user of this cut. The temperature coefficient for the XY bar is -0.033ppm/EC². The calibration, frequency at the reference temperature of high frequency crystals (AT, BT, and SC) to be within +/- 10 ppm and within several Hz for low frequency crystals is considered to be a tight tolerance, but with reasonable yields. Drive level must be limited in the application to prevent abnormal aging or damage. This drive level may need to be limited to 1 mW for high frequency crystals and as low as 0.1 mW for some low frequency crystals. Aging can also be affected by the mounting, imperfection in the quartz, and extended periods of time at high temperatures. Ceramic resonators are generally used for less accurate applications. Initial accuracy (calibration) of these devices' ranges from ±0.05% to ±1.0%. Temperature stability is approximately 15 ppm/EC for ceramic resonators. Aging is in the range of ±0.5%/10 years. These devices are much lower Q than quartz crystals and also seem to be more prone to spurious modes of operation. SAW (surface acoustic wave) devices are generally used in frequency ranges above that of the BAW (bulk acoustic wave) crystal such as the AT cut. All of the previously discussed crystals have been BAW crystals and thus the bulk of the quartz is involved in the area of excitation. The SAW involves only the surface of the substrate used. The frequency is set by the distance between the electrode "fingers" (see figure 8). 5 JL9113 Rev. B FIGURE 8 Quartz, LiTaO3, and LiNbO3 are common substrates for such devices. Initial accuracy is dependent on the accuracy of the printing of the "fingers". Initial accuracy can be in the ±50 to 200 ppm range. The approximate temperature constant of quartz is 0.03 ppm/EC² and -20ppm/EC for LiTaO3. Upper frequencies of 3.5 GHz are currently obtainable. The lower end is limited primarily by size, since the AT becomes more practical. Construction The high frequency cuts (AT, BT, and SC cuts) are generally mounted on the edges using springs or channels mounted to the posts of the holder. The mass of the blank and the mechanical shock and vibration of the application must be carefully considered. If the mounting is too stiff, the blank will break more easily. If the mount has too much "give" for the mass of the blank, the blank will hit the holder and break. Strip resonators, which are usually AT cuts, have been used in much smaller packages than the disks used for the more conventional high frequency crystals. Because of this, manufacturers have developed numerous methods to mount these basically rectangular crystals. Because of their lower mass and smaller size, the mechanical shock and vibration is not as critical as with conventional high frequency crystals. Low frequency cuts, instead of having relatively stable edges, have nodes which remain relatively motionless. These nodes are used for the electromechanical connection. Depending on the mode of vibration, there exist either one or two nodes on each of two sides. Thin wires are attached to these nodes and then the other end is attached to the posts of the packaging. This means that these crystals are suspended by two to four thin wires. Because of this and the mass of some of these very large crystals, it is obvious the mechanical shock and vibration of most low frequency crystals cannot be as high as the high frequency crystals. To package a crystal, the following factors must be considered: 1. A crystal vibrates, and thus requires air space around the area which vibrates. 2. A crystal can be quite fragile, so mechanical shock and vibration of the application and handling are very important considerations. 3. The crystal must be surrounded by an inert atmosphere. Thus, the package must be hermetically sealed. 6 JL9113 Rev. B Glass vacuum tubes and metal packages were, for many years, used exclusively for crystals. Still, one of the least expensive packages is made of metal. Sealing techniques for these metal packages can be resistance welded, solder sealed, or cold welded (a compression fit). Atmospheres inside must be void of moisture. Vacuum, nitrogen, or helium are commonly used. With the advent of the strip resonator, smaller packaging has been the focus of many companies. Some of the materials used recently are: ceramic, plastic, and glass. Ceramic or glass may be a good option as the seal is reliable and hermetic. To date, plastic is not hermetic and requires the crystal to be sealed in a secondary package inside the plastic. Ceramic resonators are either dipped epoxy or plastic encapsulant similar to capacitors commonly used. SAWs are generally packaged in resistant welded metal packages. Two sources for standard packaging for crystals are EIA (Electronic Industries Association) RS-417 and MIL-STD-683. Some of the common military type packages are HC-49/U, HC-25/U, HC-45/U, or HC-18/U for high frequency AT cut crystals, and HC-6/U, HC-33/U, HC-13/U, or HC-32/U for lower frequency crystals. EIA RS-192A can be used as a reference for standard package size for vacuum tube types. The EIA is also a good source of standard packages and registered packages which may be used in the crystal industry. Common packages must be used whenever possible to aid in developing multiple sources by preventing elimination of very good sources because of unavailable packages. Application For years now the electronic industry has used through hole packages (i.e., either packages with wire leads or sockets on the pc board and pins on the package). The wire lead option is still the most popular package type used. Although the frequency control industry is lagging the rest of the electronic industry, many manufacturers have developed surface mount packages. These packages are mostly used with the AT strip resonators. Some of the factors to consider are as follows: Through hole: 1. Generally, assembly to the pc board is a hand operation. 2. Caution must be used when cutting the leads to prevent damaging the crystal inside. 3. Soldering operation must limit the heat to prevent reflow of any solder inside. Surface mount: 1. Package standard has not yet been established. 2. SMD processes generally get the component itself hotter and thus aging is accelerated. 3. Repair is generally more difficult and may require special equipment. 4. Cost will be higher until a standard package is set and volume of usage increases. An important factor may be to select a package which fits into the flow of manufacturing already established for other components. Many of these factors listed above must be considered to prevent poor yields at the end of the process. Specification The most important factor in specifying a resonator or filter crystal is to know the circuit it will be used in. For digital devices, manufacturer's data sheets or application notes are generally very helpful in identifying the crystal requirements. Transistor and other active device oscillator circuits need to be evaluated carefully before specifying the crystal. Stray circuit capacitance and inductance can affect the actual operating point of the crystal greatly. 7 JL9113 Rev. B Specifications should include the following: 1. The frequency of operation. 2. Series or parallel mode of operation. 3. If parallel, the load capacitance seen in the circuit. 4. The maximum Motional Resistance for a series crystal or maximum Equivalent Series Resistance for a parallel crystal. 5. Frequency tolerance at a reference temperature (calibration) and frequency shift over a temperature range (drift) or the frequency tolerance can be specified to include both in an overall tolerance allowing the manufacturer to trade off one for the other. 6. Aging, or the amount of frequency shift over a long period of time, should be specified or included in #5 above. 7. As discussed earlier, a standard package is preferred. The package must be compatible with the crystal required. A manufacturer may need to be consulted. 8. Co, C1, or L1 requirements need to be specified if the circuit operation depends on it. Generally C1 or L1 need not be specified for oscillator circuits and Co is generally a maximum requirement. Oscillators which require the resonator to change frequencies (such as VCXO) will need to specify Co and C1 or simply specify the pullability (the frequency shift required with a specified change in load capacitance). 9. The maximum drive level the resonator can expect in the circuit. 10. Any mechanical shock or vibration the device will be exposed to in the application must be specified. MIL-C-3098 can be used as a reference for many of these requirements, but it is a good idea to check with a couple of manufacturers for feasibility before finalizing the specification. Testing One simple, but not quantitative, way to test the crystal would be to place the crystal in the circuit. If this method is used, it is common to supply manufacturers with the circuit also for correlation purposes. This method can only verify the resonator functions and the frequency can be measured with a frequency counter. The CI-meter (crystal impedance meter) was designed to measure motional characteristics' R1, C1, and L1 of a crystal. Later models also measure the shunt capacitance (Co). The frequency of operation is measured by adding a frequency counter. It is possible to measure the frequency of operation of a parallel resonant device by simply placing a capacitor of the value of CL in series with the crystal and then placing this combination into the CI-meter. This type of active tester has been improved and expanded upon (such as Saunders and Associates) in recent years. Some of the improvements include direct reading of R1, automatic insertion of the load capacitance, etc. Two methods of passive measurements have been developed into standards for crystal measurement. One is the EIA-512, which uses a Network Analyzer (or similar type equipment). In this method the signal and measurement devices are connected directly to the crystal. The other (developed in Europe) is the IEC#444. This method is very similar to the EIA-512 except that it uses a pi-network to connect the crystal to the signal and measurement devices. Both methods measure phase and impedance versus frequency to calculate the crystal parameters. The detailed standards should be studied if these methods are to be used. To date at least one software program has been marketed to assist testing using the EIA-512 method of measurement. 8 JL9113 Rev. B OSCILLATORS Oscillators require a resonator, per the previous section, and an active device. Typically additional resistors and capacitors are also required in the circuit. Theory of operation Two requirements must be fulfilled in order to obtain oscillation in the closed loop circuit: 1. The closed loop gain must be greater than or equal to one. 2. The phase shift around the loop is N*360E, where N is an integer. In addition, it is important to note that at power up the noise of the component around the oscillator circuit is what actually starts the oscillation. Some of the active devices used are discrete transistors, Field Effect Transistors, Op-Amps, and digital gates. A common transistor circuit is shown in figure 9 (colpitts oscillator). FIGURE 9 A typical digital gate circuit is shown in figure 10. FIGURE 10 Matching the resonator to the oscillator circuit is the responsibility of the manufacturer. In designs where the crystal is not enclosed before it is married with the oscillator circuit, the manufacturer can final adjust in the circuit. This eliminates the frequency shifts due to circuit variations. The oscillator circuit is typically buffered so variations in load do not greatly affect the frequency stability. 9 JL9113 Rev. B Characteristics Clocks are a subset of the general crystal oscillator (XO) type. Clocks are usually used to supply frequency timing to digital circuits and microprocessors. Clocks are typically available in the same technology as any other digital IC's such as TTL, CMOS, ECL, etc. The frequency range of these clocks is primarily limited by the technology being driven such as 75 MHz for STTL, 125 MHz for 10k ECL, etc. The frequency characteristics are basically that of the crystal being used (AT cut is mostly used). Clocks can obtain calibration frequency tolerances of below ±10ppm. The oscillator circuit could add to the crystal drift depending on the temperature change of critical resistors, capacitors, or inductors in the oscillator circuit. Typically the circuit will be insignificant in the frequency variation. The clock is the simplest of all the oscillator types. Because of this, they are smaller, cheaper, and uses less power to operate than other types. Start-up time (the time it takes to start the oscillator once power is applied) ranges from under 1 msec. to 20 msec. The clock oscillator generally requires only one power supply voltage for operation. VCXO, or voltage controlled oscillators, can have the output frequency change with a change in voltage at a control pin of the oscillator. VCXOs are used in many applications such as telecommunications, TCXO, or phase locked loops. The amount of frequency shift with a given voltage change (pullability) is highly dependent on the oscillator circuit. Pullability of 35 to 50 ppm/volt are common and higher pullabilities are obtained by adding an inductor to "de-Q" the crystal. Most, if not all, VCXOs use varactor diodes to vary the frequency. The varactor diode changes the capacitance across its terminals based on the DC (or low frequency AC) voltage across the same terminals. The frequency calibration and drift are basically that of the standard clock oscillator. Calibration may be degraded somewhat by the additional variable of setting the control voltage where this calibration is defined at. Since the crystal load capacitance is varied by the varactor diode, the drift over temperature varies from one end of the control voltage to the other. Thus, the drift can not be optimized for all control voltages. Those circuits that require "de-Qing" the crystal will have worse drift than the crystal by itself. TCXO (temperature compensated crystal oscillator) adjusts the frequency for temperature variation. An integral part of a TCXO is a VCXO. Connected to the VCXO is generally a network of thermistor designed to bias the voltage control of the VCXO properly for each temperature. Recently, other compensation techniques have been used such as digital processing. TCXOs commonly have an outside adjustment for setting the calibration frequency periodically. This is to compensate for the aging of the crystal over time. The period between calibration will depend on the accuracy required and may range from once a month to once a year. Frequency drift can be expected to be in the ±1 to 5ppm range. Some of this tolerance comes from frequency versus temperature hysteresis (i.e., the difference in frequency at a particular temperature depending on whether the temperature was increasing or decreasing. Power dissipation is typically two to three times that of a standard clock oscillator. The size and cost of these devices are also larger than a standard clock oscillator. After power-up it could take as much as 100 msec or more for the frequency to stabilize in a TCXO. The TCXO may also require multiple power supplies depending on the design. OCXO, oven controlled crystal oscillator, uses an oven to stabilize the frequency variation. The oven contains, at a minimum, the sealed crystal. The oven temperature, to maintain control, must be higher than the maximum ambient temperature expected in the application. The crystal is selected so that it has nearly zero frequency change in the range of temperatures expected in the oven (usually less than ±5EC). Frequency tolerances of much less than ±1ppm are realizable with an OXCO. Additional circuitry is required to control the oven and maintain the proper temperature inside. Customarily, similar to the TCXO, a calibration must be done periodically to compensate for crystal aging. A separate power supply is used for the heater in the oven. Isolation between this supply and others required by the oscillator must be established because of the noise generated when the heater is activated. The power required is considerably higher than a standard 10 JL9113 Rev. B clock oscillator (as high as several watts of power). Again, cost and overall size is much more than that of a clock oscillator (as much as 40 times the cost and size). OCXOs are popular as timing standards in the instrumentation market in such measurement equipment as frequency counters, spectrum analyzers, network analyzers, etc. Another variety of "XO" type of oscillator has a sine-wave output. The output is generally specified into a fixed load and has a harmonic distortion specification. The sine-wave oscillator usually incorporates an AGC (Automatic Gain Control) circuit to ensure constant amplitude. Usually the TCXOs and OCXOs are also sine-wave outputs. Two other types of oscillators, more recently developed, are the MCXO (Microcomputer Compensated Crystal Oscillator) and the DCXO (Digitally Compensated Crystal Oscillator). As their names imply, both compensate for the frequency shift with temperature. Either may be capable of improving on the TCXO performance without a large power usage. Combinations of the above oscillators have been developed for some special applications. A TCVCXO is a Temperature Compensated, Voltage Controlled Crystal Oscillator and an OCVCXO is an Oven Controlled, Voltage Controlled Crystal Oscillator. With the ability to put more complex circuits in an IC has enabled IC vendors to produce phase locked loop devices. Although a recent development, they are becoming increasingly popular. They basically use a stable crystal oscillator as a reference to a VCO or VCXO and a feedback loop. This design gives an output close to the stability of the crystal oscillator, but with various dividers can produce various output frequencies which are digitally selectable. This design is becoming very popular in the video market and other applications previously requiring multiple oscillators. Construction The Crystal Industry has long been innovative in packaging. All packages are hybrids of various packaging/hybrid techniques. The common clock oscillator generally uses a thick film circuit printed on a ceramic substrate. Discrete components are either soldered or epoxied to the circuit. High temperature solder must be used, if soldering is done, to prevent the components from letting loose when the clock is soldered to the PC board. ICs are usually placed in DIE form and wirebonded, or procured in SOIC-type packages and soldered in place. Since most clocks use the high frequency cuts (AT, BT, or SC), the crystal blank (disk) is mounted on the substrate without the crystal being sealed in a secondary package. Crystal mounting hardware ranges from solid metal blocks to springs to thin punched metal pedestals. For most applications, the hardware which has some "give" to it seems to be best for mechanical shock, mechanical vibration, and thermal shock. The substrate is mounted to a metal header and has a metal cover which is resistance-welded on. Other more complex oscillators, such as TCXOs, VCXOs, and OCXOs, use much different techniques. Although recently some of the simpler VCXOs and TCXOs have utilized Application specific ICs and other high technology techniques to miniaturize them into similar packages as the clocks, most still use a common pc board, leaded ICs, and a sealed crystal. These are in a rather large metal base with a metal cover either screwed or soldered to the base. Sealing the entire package is not critical, since the crystal is sealed inside. Clock oscillators are available in two package sizes; one is in a hybrid DIP with 0.300 inch row spacings and 14 pin compatible, the other is the same, except that it is 8 pin compatible. Usually only the 4 corner pins are present, since the other pins are not required for either electrical or mechanical purposes (see figure 11). 11 JL9113 Rev. B FIGURE 11 There seems to be very little standardization for the more complex VCXOs and TCXOs. They generally take up three to five times more PC board area than the smaller clock oscillators. Application The frequency control industry has made the metal hybrid resistance weld package a reasonably high volume/low-cost package option. Even today it is by far the most widely used package in either the 14 pin version or the 8 pin version. Although surface mount packages have been slow to come to the frequency control industry, many manufacturers have introduced a version or have one under development. Many manufacturers have offered an SMD version of the above metal package with a gull wing lead bend. This has not been accepted throughout the electronic industry as fulfilling the needs of a true SMD package. A number of true surface mount packages have been developed by a number of manufacturers. Most use either a plastic package with a secondary-sealed package inside (either just the crystal or the whole oscillator), or a ceramic package. None of the leaded surface mount packages are industry standards, but some are being evaluated by the EIA. Because of the complexity of the circuits, the TCXOs and OCXOs are available in through hole versions only. A number of factors need to be considered when selecting through hole or surface mount packages: Through hole: 1. Hand assembly of component to the PC board. 2. Soldering operation must limit heat to prevent reflow of any solder inside. Surface mount: 1. Package standard has not yet been established. 2. SMD soldering process usually gets the component itself hotter and thus aging is accelerated. 3. Repair is generally more difficult and may require special equipment. 4. SMD packages will be higher cost until a standard is set and volume increases. 12 JL9113 Rev. B Other important factors are second source availability and how the oscillator package fits into an already existing flow of manufacturing. All of these factors, plus any special ones, must be carefully evaluated to prevent poor yields at the end of the process. Specification When creating an oscillator specification, it is important to consider what the application expects of the oscillator and not just "boiler plating" a specification. This practice could cause undo expense when purchasing the components. It is common, and possibly easiest, to specify the frequency tolerance over all specified conditions such as temperature, voltage, calibration, etc. If individual requirements are to be specified, all expectations should be specified. Temperature drift, calibration, variation with voltage, variation with load, and aging are all frequency tolerances required to completely specify the oscillator. In addition, voltage controlled versions must also have frequency change with control voltage variation specified. It is important for the aging characteristic for the maximum operating or storage temperature to not be specified higher than necessary for the application. Unless otherwise specified, the aging requirement is assumed to be at 25EC or, at a minimum, the average temperature is 25EC. Whether the oscillator is a clock or a sinewave output, it is important to clearly specify the load that the oscillator will drive in the application. Load capacitance expected may be difficult, but necessary, to specify. The stray load capacitance on the PC board may be distributed over a trace inductance. In this case, an estimate will need to be made. Another problem area may be in using the TTL industry equivalent load at higher frequencies. The diodes customarily used in these loads do not switch fast enough to represent the actual faster TTL technology. For clock oscillators, the digital waveform must be specified. The logic level limits expected into the specified load must be defined. These logic levels are basically defined by the specific device being driven or the technology of the device being driven. The Rise and Fall times or the speed at which the oscillator transitions between logic levels must be specified. The levels at which these measurements are taken need not be the logic levels. The symmetry (duty cycle or squareness) is normally specified as the time the output is higher in voltage than the threshold voltage of the device being driven over the period. The threshold voltage must be between the logic low and the logic high. For oscillators with sinewave outputs, the output waveform characteristics must be defined. The amplitude of the sinewave output is usually expressed in volts peak to peak, or in dBm. Harmonic distortion (the amplitude of the portion of the signal which is at three times, five times, seven times, etc. of the main output frequency) is specified in dB below the main output frequency. In some cases, it is desirable to specify a noise level or non-harmonic distortion. This is useful to limit distortion due to such techniques as doubling (this may produce a distortion at 1.5 times). 13 JL9113 Rev. B All oscillator specifications should limit the power or power supply current to the amount available to the oscillator. Breakdown voltage or absolute maximum power supply voltage must be specified (most digital gates require less than 7.0 volts). Start-up time after power is applied should be included in the specification. Another important parameter, especially in overtone oscillators (oscillators over 25 MHz may use overtone crystals), is the range of time it takes the power supply to ramp up to operating voltage seen during testing and in the application. Very long or very short power supply ramp-up times may cause the oscillator to start and operate on the wrong mode of the crystal (in the fundamental instead of the third overtone, or the fifth overtone instead of the third overtone). Some of this affect is due to critical filtering condition. Also involved is the active device characteristic known as gain-bandwidth product which is lower at lower voltages, and higher at higher voltages. Thus, this gain-bandwidth is changing considerably during power up. Phase noise or phase jitter has become an important parameter recently. Phase noise or jitter is the short term variation in the period. This characteristic can be specified either in the frequency domain or the time domain. The actual specification will depend greatly on the application and should be worked closely with the manufacturer. The mechanical shock and vibration the device is expected to withstand must be specified. Also, any other special application conditions or requirements not listed above should be in the specification if it might affect oscillator performance expectations. Some other examples of parameters needed may be power supply isolation, signal overshoot, or signal undershoot. Testing Most of the basic measurements of a clock oscillator can be measured using a frequency counter to measure frequency, a current meter or DVM to measure power supply current, and an oscilloscope to measure the voltage levels, rise and fall times, and symmetry. In some cases, a Time Interval Counter can replace the frequency counter and oscilloscope. The same setup can be used for a sinewave oscillator if the output is defined as peak to peak voltage. If the sinewave oscillator output is defined in dBm, then a Spectrum Analyzer is required. In most cases, the Spectrum Analyzer is required to measure the distortion of a sinewave oscillator. The bandwidth of the oscilloscope or input stage of the time interval counter is important to the accuracy of the waveform measurement. In the case of the clock oscillator, the ideal waveform would be a square wave. The square wave is made up of sinewaves at the fundamental frequency (the output frequency specified) and all of the odd harmonies of that frequency. Since the amplitude, or the amount each harmonic contributes diminishes as the harmonic order increases, the lower orders are most important in our waveform measurements. If the clock oscillator output frequency was 50 MHz, then the oscilloscope bandwidth must be 150 MHz minimum to adequately involve the third harmonic in the measurement. Also, this minimum bandwidth must be a combined oscilloscope and probe bandwidth. If overshoot or ringing in the waveform is critical to the application, the oscilloscope bandwidth may be set by this rather than the oscillator frequency. It is common for overshoot to have a duration of approximately 1 nsec. If this is assumed to be approximately one-half of its period, the period would be 2 nsec. and the frequency content would be 500 MHz. Thus, the minimum combined bandwidth of the oscilloscope and probe becomes 500 MHz. 14 JL9113 Rev. B Fixturing for clock oscillator testing is becoming a critical factor in measurement ability as output frequencies rise. Sinewave oscillators are generally specified into 50 or 75 ohms and can utilize a clean transmission line for interconnection. But, TTL or CMOS type of outputs for the clock oscillators cannot utilize the standard transmission lines. For these applications it is important to minimize stray fixture capacitance. Keep the load and test points as close to the oscillator output as possible. It is very important to use good RF circuit techniques when building oscillator test fixtures as well as the actual application circuit. As noted earlier, the industry TTL equivalent load uses diodes which may not be adequate for higher frequencies due to switching times. Before using faster diodes, the customer and manufacturer must agree on the change. The power supply ramp-up time should be known for the test equipment being used to power the oscillator. The power supply ramp-up time must be within any limits set in the specification. In some cases start-up may be verified at each extreme if specified. Various methods are used to control this. One is to use a simple RC time constant in the power supply line. Another is to use a waveform generator to drive the oscillator's power supply line. In general, crystal oscillators are simpler to use in a design and require more traditional test equipment than a discrete crystal. The crystal oscillator also puts more of the design and verification burden on the manufacturer. 15 JL9113 Rev. B References: Raytheon Saw Devices Technology 1/87. Toyocom Saw Devices 1989/1990. Sawtek Saw Scene summer 1986. NTK Technical Ceramics 1985. Fujitsu Acoustic Resonator data sheet NEL Catalog 380(1982) NEL Catalog 9001 Quartz Crystal Resonators and Oscillators, a Tutorial by John R. Vig U.S. Army Electronics Technology and Devices. Introduction to Quartz Crystal Unit Design by Virgile E. Bottom, Ph.D. VanNostrand Reinhold Company Design of Crystal and Other Harmonic Oscillators by Benjamin Parzen/Arthur Ballato John Wiley & Sons Crystal Oscillator Circuits by Robert J. Matthys John Wiley & Sons Handbook of Piezoelectric Crystals for Radio Equipment Designers WADC Technical Report 56-156 by John P. Buchaman Office of Technical Services,U.S. Department of Commerce. EIA-512 Electronic Industries Association Engineering Department 2001 Eye Street,N.W. Washington, D.C. 20006 IEC#444 International Electrotechnical Commission 1,rue de Varembé Genève,Suisse 16


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This Turkey Day vacay: host a friendsgiving feast!
This sweetie gave an unexpected kiss for the camera
I know I am pretty but I don't have a BF. Is something wrong with me?
The biggest OMG celeb moments of the week
Feel-Good Friday: Tiffany the Terrier eats her pro-ice hockey playing owner's passport
How to look like the trendy one at Thanksgiving
All-natural lippies you can actually eat
4 sneaky moves for stronger and leaner posture
Should you get back with your ex?
What do you think of our Dec/Jan issue? We wanna know!
Kirby Buckets Clip
It's all about fashion !
I Know What Boys Like!
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For Each Other
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Fashion Everythings
Here's a *free* excerpt from Bella Thorne's new book!
Bella Thorne's got a new book series—
and it's amazing.
CLICK HERE for everything you need to know about the first novel, Autumn Falls—plus a Q&A with Bella and a *free* chapter sampler!
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Added August 9, 2010 4:04 PM
Good morning, KELOLAND! Bundle up: it's windy outside this morning.
Coming up KELOLAND This Morning: Low fuel prices spurs holiday travel; A South Dakota woman is traveling to Buffalo to help with the flood respond.
-331 Minutes Ago
KELOLAND News will be on at 10:40 p.m. Tonight, three people have been arrested after a deadly stabbing in Wagner this weekend. #kelonews
4 Hours Ago
While many didn't like the snowfall that hit Sioux Falls last week, it helped one KELOLAND business. #kelonews
7 Hours Ago


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Ryan Seacrest is showing his dominance in the TV world. After producing not only one or two TV shows, Seacrest is in the middle of producing another one in an area which he has not explored yet, dancing.
In its exclusive report, THR stated that Ryan Seacrest Production is piloting a show that will also bring Lady GaGa's choreographer Laurie Ann Gibson on board. Little is known about the project but it is basically revolving around choreographers and dancers in Los Angeles.
Gibson is confirmed to be one of the cast members. Her credit includes the dance sequence in GaGa's "Paparazzi" and "Telephone" as well as FOX's "So You Think You Can Dance".
Seacrest, the busy man behind "Kourtney and Khloe Take Miami" and "Jamie Oliver's Food Revolution", is also developing another show which will help people with disorder, compulsion, weird phobia and unusual problem. Called "The Incurables", the show puts therapist Paul Mckenna on duty to 'cure' the problems.


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Last week two thirds of the CorvetteBlogger wolfpack was out in Las Vegas
wandering around the desert looking for strippers and cocaine at the annual SEMA show. The SEMA show is the banner event for the automotive aftermarket industry. This year 125,000+ attendees perused the latest wares from hundreds of suppliers. Countless custom rides become the show pieces to display the newest products and industry trends. SEMA is only open to members, buyers, vendors, and media. Don't fret if you couldn't be there as our Corvette photo gallery awaits you just beyond the Read More button below.
C2 Corvette
Last week two thirds of the CorvetteBlogger wolfpack was out in Las Vegas
The third time proved to be the charm for Brian Hobaugh.
Hobaugh had finished third in 2011 and moved up to second in 2012 (losing by just a point) with his 1973 Camaro in the OPTIMA Batteries Ultimate Street Car Invitational before finally pulling out a victory with his family's 1965 Corvette in the sixth annual event held in Pahrump, Nev., on Saturday.
Photo Credit: Barrett-Jackson
The high performance Corvette market is red hot. One of several recent examples was the world's record price set this past September for a Corvette at auction, a 1967 Corvette L88 sold for $3.2M. You can bet that owners of high performance Corvettes who want to sell will be jumping on the bandwagon to take advantage of the sizzling Corvette market and the huge audience the Scottsdale auctions provide.
Taking advantage of the current red hot vintage Corvette market, Barrett-Jackson will be offering George Barris' customized 1963 second generation Corvette known as "Asteroid" during their January auction extravaganza in Scottsdale, Arizona, January 12 -19, 2014.
Brian Hobaugh and his 1965 Corvette to Compete in the 2013 OPTIMA Batteries Ultimate Street Car Invitational
We told you a few weeks ago about a one-of-a-kind 1965 Corvette Sting Ray that has been on the track since it was born – and in the same family for more than 30 years. Brian Hobaugh will again be aiming for the top prize with his family's Corvette in the OPTIMA Batteries Ultimate Street Car Invitational 2013 on Saturday, Nov. 9 from 7:30 a.m. to 4 p.m. (PST) in Pahrump, Nev.
It's time for Throwback Thursday where we feature vintage photos of Corvettes. Today's selection shows a young man distracted as he's fueling up a Corvette Sting Ray.
The National Corvette Museum has received its largest donation ever – a collection of 10 Corvettes in the Don Messner Collection.
Messner, who passed away in May from melanoma, wanted to inspire others to make similar donations in the future.
In 1970, Cliff Gottlob and Jack Blatchford drove a 1967 Corvette to Daytona Beach, Fla., where Gottlob and David Dooley teamed up to drive the L88-powered 'Vette to second place in a 24-hour endurance test.
Now, 43 years later, Blatchford drove the same car onto the lawn of the 18th fairway at the prestigious Concours d'Elegance at Pebble Beach Golf Links.
Once again our friends at ProTeam Corvette Sales will be hosting a NCRS Technical Seminar. This year's event is coming up on November 9th and the main topic is "How Chevrolet's Relentless Pursuit of HP Benefited Corvette". The all-day session is co-sponsored by the Michigan and Heart of Ohio chapters of the National Corvette Restorers Society (NCRS). NCRS membership isn't required to attend and the cost is just $20 at the door. That admission fee also includes breakfast and lunch.


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Maybach Music Group's Meek Mill may be taking his issues with Cassidy to the next level after reportedly posting a photo of himself alongside his rap foe's mother.
Meek posted the photo allegedly alongside Cass' mom Friday (December 28) night.
"Wit y'all mom too! @kattizchillin@slick_np @ambitiousmeen," he posted December 28th. (Meek Mill's Instagram)
Some sites speculate the image could be dated and a strategic ploy to get at the rap veteran.
Anyway, Meek Mill may be taking things to another level on these social networks. The other day he posted a picture of himself and Cassidy's mother! First of all, shouldn't she be watching Oprah or something? Or maybe knitting? I guess not. Now, I am going to assume that this is an old pic that Meek dug up to get under Cass' skin but you never know! Even if it IS old, I think its a bad karma move to start putting parents and kids in the beef under any circumstances. (AHH Rumors)
Coincidentally, Mill promised to fall back on their feud a day prior to posting the shot.
"No more attention on broke n*gga sh*t….. I'm done…. Time 2 get this money! Nothing else #mmg #dcr," Meek tweeted December 27th. (Meek Mill's Twitter)
This all comes days after Meek dropped his hard-hitting "Repo" diss track.
"What you made this year, what you worth n*gga," Meek continues. "I dropped Dreams & Nightmares, I made 'Church' n*gga, I did 'I'ma Boss,' young'n set the summer off/Now these old n*ggas mad at me 'cause they fallin' off/Get your hate on, Cass, and we ain't talkin' Larceny 'cause they all trash/Your goons ain't riding with you 'cause they all mad/You ain't never put no food up on AR Ave/My dog caught a body for you, d*mn, he ain't eatin' from it/Now you mad at Swizz 'cause you can't get a beat from him/Once my n*ggas come at you dog, we gonna keep coming/Weird ol' Forrest Gump a** n*gga, better keep running." ("Repo")
Check out "Repo":


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Md. college hosts discussion of NFL concussions
A symposium at Mount St. Mary's University asks people to consider some difficult questions about National Football League player concussions.
Tags: concussions, nfl, Mount St. Mary
Mount St. Mary's ready for tournament challenge
After battling to win the Northeast Conference championship this week, Mount St. Mary's is ready to take on the NCAA Tournament.
Tags: NCAA tournament, Northeast Conference, Mount St. MaryListen
Sacred Heart upsets Mount St. Mary's, 72-65
Freshman De'Von Barnett fired off the Sacred Heart bench to score a career-high 22 points to lead the Pioneers to their second Northeast Conference victory, upsetting Mount St. Mary's, 72-65 Thursday night.
Tags: Mount St. Mary, basketball
Seminary, Latino community leaders react to pope's election
Monsignor Steven Rohlfs, rector of Mount St. Mary's Seminary in Emmitsburg, picked the right country of origin but the wrong person in predicting who would become the next pope.
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AP Entertainment Writers
UNIVERSAL CITY, Calif. (AP) -- Jenni Rivera's "celestial graduation" was marked by festive music, heartfelt speeches in Spanish and English and passionate chants of "Jen-ni! Jen-ni!"
Rivera's children and famed singers Olga Tanon and Joan Sebastian performed during the nearly 2
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There has been an increase in demand for wireless speakers and headphones lately. So much so, that it gets confusing as you choose from a variety of Bluetooth speakers, with varying specs, prices and quality. Braven decided to set itself apart from the rest by coming out with a fine-looking speaker made for your home … Read More
Gadget Reviews
Sol Republic Tracks Air Review
Lately, there has been an increase in demand for wireless headphones and speakers. And in response to that, Sol Republic, a company founded by music lovers and audiophiles, has partnered with Motorola to deliver a Bluetooth version of its popular Tracks headphones, the Tracks Air. Review is up. Key Features: A2 Sound Engines with premium … Read More
Bose SoundLink Mini Bluetooth speaker review. Buy one.
We've always known Bose to produce high quality audio products. I was blown away by what I've seen (or rather heard) so far. Now, I have the SoundLink Mini Bluetooth speaker here for review. And I think I'm in love with it. SoundLink Mini Bluetooth Key Features: 3.5 mm auxiliary input Micro-USB port Wireless range … Read More
Ekoplay Bluetooth Speaker review. Small Bluetooth speaker under 1K.
The Ekoplay is a small portable Bluetooth speaker by Ekotek. It's light, handy and more important, affordable. We've got one for review. Let's see if it's got what it takes. Review is up. Ekoplay key specs: 250mAh battery 3 hours playing time via Bluetooth, and 6 hours on line-in Built in microphone The Ekoplay is … Read More
KitSound Manhattan Bluetooth Headset review
Most Bluetooth headphones are expensive. Good quality ones are even more so. However, those crafty people from KitSound have begun blending quality with reasonable prices. Enter the KitSound Manhattan Bluetooth Headset. This on-ear upstart is here to prove it can go up against its more expensive counterparts. It's minimalist looks might surprise you. Review is … Read More
WD My Passport Ultra 10th Anniversary Edition Review
WD celebrated their 10th anniversary with the release of the My Passport Ultra Anniversary Edition. We have the 2TB version here and its fast and pretty. Review is up! The WD My Passport Ultra Anniversary Edition is features a beautiful aluminum radial design casing, and a USB 2.0 and USB 3.0 plug. Compatible with both … Read More
Kit: Power Bank review
Kids, charge your phones and tablets before you leave the house. But in case you forget, it's nice to have a high capacity power bank handy. Kit: Power Bank review is up. DESIGN: The Kit: power bank is a shiny square-shaped block. The top and bottom plates are made of a shiny glass-like material. For … Read More
JBL Synchros S300i Review: Style and performance
The JBL Synchros S300i provides that balance between size, style and performance. Is the price JBL is asking for this set of premium headphones worth it? Review is up! DESIGN: The Synchros S300i is made of a beautiful combination of metal and plastic components. The headband is made of metal with a soft cushion for … Read More
Bose Wave Music System III review
Bose usually makes great products. Be it for home, office or personal use, they really deliver in style, comfort and sound quality. The Bose Wave Music System III is no different. It looks good and sounds good as well. Review is up! KEY SPECS: Touch-top controls for on/off/snooze Clock / Alarm FM/AM radio CD/MP3 CD … Read More
JBL J88 Review: Powerful bass, premium looks
JBL has always been proud of what they do best: good sounds with good looks. With the J88, the audio company crafted a good sounding over ear set of cans that features stylish looks and premium design. WHATS IN THE BOX: The J88 over ears came with the following: 1.3M, single-side, detachable, flat elastomer cable … Read More
The LG G3 Review: Is it the new king of the Android hill?
When the LG G3 came out, everyone took notice. It was big. It was fast. It was beautiful. Talks of a new King of Androids were buzzing. And it looks like the G3 is set to take the throne. I know this review is a bit late, but here is my take on the LG … Read More
Moto G Review: My Daily Driver
I can't afford to buy the latest smartphone. Instead, I carefully choose my next phone purchase by looking for that balance between specs, performance and price. So about 4 or 5 months ago, I decided on getting a Moto G. And here is my quick (albeit very late) review of my daily driver. You're probably … Read More


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Ain't joining them greenskins.
Ain't joining them greenskins.
The Garithos incident can't really be blamed upon the new Alliance of Stormwind, and formed only a lesser of many reasons behind the later accession of the Blood Elves to the Horde.
Bran Bronzebeard is a bit of a rebel treasure hunter
My weekly podcast can be downloaded here this week we discuss the Warlords of Draenor launch night and a butcher that goes insane


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"A stunning group unlike any other… absolutely electrifying!" Garrison Keillor, A Prairie Home Companion
Get into a spirited, sing-along, *party* mood this holiday season with award-winning songwriter-pianist Whitney Wolanin and Her Shenanigans™ Band!
Jim Brickman will remind you, on a winter's night, of what we cherish during the most wonderful time of the year - togetherness.
Kenneth Cooper conducts Brandenburg Concerto No. 1, along with more festive and celebratory music by Bach, Mozart, and Haydn!
"100 Greatest Stand-Ups of All Time" - Comedy Central
More info about one of Comedy Central's "100 Greatest"
Conductor Ignat Solzhenitsyn and the venerable Mariinsky Orchestra bring to Troy the best of Russia: Tchaikovsky, Prokofiev, and Rachmaninoff.
Showcasing one of the greatest contemporary voices of our time, Linda Eder's diverse repertoire spans Broadway, standards, pop, country and jazz.
For a pass including both nights of the Bridge Jazz Festival, please call us at (518) 273-0038!
"Sometimes I feel like a figment of my own imagination." Lily Tomlin
Les Violons bring their superior artistry to bear on a program of chamber pieces by Haydn and Mozart, including Haydn's "Farewell" Symphony, No. 45.
"Irish Music at its Best"- Danny Matheson, Celtic Music Radio
"They have it all: lead vocals, brother-duet harmony, instrumental virtuosity, ensemble sensibilities & great original material." -Bluegrass Unlimited
Pablo Ziegler and Christopher O'Riley, having toured the critically acclaimed Los Tangueros, partner again on an adventurous new program.
Making his solo debut at the Hall in a concert that, paired with the room's exceptional acoustics, promises to be a uniquely intimate experience.
"At the top of her game…" - San Francisco Chronicle
Anton Bruckner: Symphony no. 4 in E flat major, "Romantic", world premiere of the 1878 version, researched by Louis Lohraseb and William Carragan
Her voice is spectacularly pristine, a clarion call almost overpowering in its beauty more than 55 years since she first performed


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Jonathan Burchfield
Partner and head of charity team, Stone King LLP
Jonathan's experience covers both private client and charity matters but he has concentrated almost exclusively on charity matters since the early 1990s. He was a partner with Nabarro Nathanson before joining Stone King LLP in May 2006.
Jonathan's work focuses on advising charities on all aspects of charity law and practice, and on their corporate governance. He is also head of Stone King's legacy team and as such advises charities on all aspects of legacy fundraising and administration. He regularly speaks and writes on charity law matters.
Jonathan stepped down in June 2007 after some 12 years' service on the executive committee of the Charity Law Association (having acted as its deputy chairman for some years). He is a trustee (and former chairman) of the Tubney Charitable Trust, a significant grant-making charity.
He has recently completed a term as trustee of Creativity Culture & Education, a charity established by the Arts Council in order to take over from it the running of the government's flagship creative learning programme with schools, and is a governor of St Edward's School, Oxford.
Jonathan is a member of the firm's management team.
Is this profile up-to-date? If not, please let us know at email@example.com
Defending the right
7 Nov 2014
Ian Allsop calls for a charity to be set up to campaign on behalf of oppressed right-wing politicians.
Fiery rocket or damp squib?
4 Nov 2014
As bonfire night approaches, John Tate is cautious about the pace of the new developments setting the...
The social investment arguments are not black and white
3 Nov 2014
Social finance is not wrong for the voluntary sector - but we must learn lessons from history, says Ashley...
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Attending our one day courses is a highly effective way of ensuring new and existing trustees fully understand their role, responsibilities and liabilities.
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12 Feb 2015
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9 Mar 2015
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Spartanburg, SC — AFL announces the introduction of the Noyes OFL280 FlexTester, a hand-held, multifunction OTDR and loss test set offering incomparable flexibility and exceptional value. With unmatched combinations of fiber optic test functions, ease-of-use and portability, all OFL280 FlexTester models include an integrated single-mode 1310/1550 nm OTDR with PON-optimized and standard test modes, optical power meter, 1310/1550 nm laser source and visual fault locator. The OFL280 FlexTester will replace or upgrade four existing OFL250/OFL280 models:
Operating at 1310/1550 nm, the OFL280-100 is suitable for certifying point-to-point or FTTx PON fibers, allowing the detection of macro bends. The OFL280-101 adds 1625 nm, allowing certification of the L-band for transport use. Testing at 1490 nm is required by some network operators to certify FTTx PONs, making the OFL280-102 the best choice. The filtered, three wavelength OFL280-103 certifies dark fibers at 1310/1550 nm, fault-locates live FTTx fibers at 1625 nm, and measures FTTx power levels at 1490 and 1550 nm, all from a single test port. All OFL280 FlexTester models can test through FTTx PON splitters!
As with all Noyes OTDR's, test results may be saved as industry standard .SOR files, which can be transferred to a PC for viewing, printing and analysis using supplied Windows® compatible software.
The enhanced-capability OFL280 FlexTester will replace comparable OFL250 and OFL280 models with no price increases. For additional information, visit www.AFLglobal.com.
About AFL
AFL is an industry leader in providing fiber optic products, engineering expertise and integrated services to the Electric Utility, Broadband, Telco, OEM, Private Network and Wireless markets. It has operations in the U.S., Mexico and the U.K. AFL is a division of Fujikura Ltd. of Japan.
Chris Blair
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AFL associates, including friends and family, boxed, moved and unloaded supplies and furniture from the old location to the new facility, without interrupting operations
AFL has been awarded five patents for new technologies
Catalog features a complete schedule of training dates and locations throughout the United States and Canada for each of Light Brigade's 16 training courses
New 432-fiber OSP MicroCore is one of the world's smallest high fiber count fiber optic cables with a stranded core geometry
Outer diameter of cable is minimized by using Spider Web Ribbon (SWR) technology
© Copyright 2014 AFL. All Rights Reserved | Sitemap


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posted by Colm Hanratty | 0 Comments
This evening I took to the streets of London to take some photos of London at night. The city looks extremely beautiful at night as you can see. I started off down on the Thames to get shots of the London Eye and Big Ben, then went from there to Tower Bridge before hitting the West End to for shots of Leicester Square and Piccadilly Circus.
The above is just one of thirteen photos I took tonight that will be available on our facebook page on Friday and a photo essay at a later stage. In the meantime though, hope you like this one.
And if you're planning on visiting London, you can book cheap hostels for London on Hostelworld.
In our hostelworld.com travel blog we bring you all the latest company news and information on new additions to the site including podcasts, videos and more. You'll also get inside information on a variety of destinations across the globe as they're visited by our travel editor and writers.
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- Musician's Friend Best Selection, Price & Service. Guaranteed.
Call our Gear Heads
at: 800-449-9128
Call our Gear Heads
at: 800-449-9128
Lightweight, portable 8-track digital multitrack recorder.
Portable digital recorders are a necessity for all songwriters, and the TASCAM DP-008EX Digital POCKETSTUDIO is a great choice. Jot down all of the key components to your songs using this professional sounding multi-track recorder. Be ready wherever creativity strikes.
Built-In High-Quality Stereo Condenser Microphones
The DP-008EX comes with two condenser microphones built directly in the front of the unit so you can record vocals or acoustic guitar anytime without the need for extra equipment or setup time. TASCAM held many evaluation tests to secure the best sounding microphones and structures. Modeled after the top-selling DR Series microphones, you can be assured you're receiving top-quality. Moreover the DP-008EX was designed with a tripod mount for versatile set-up and placement.
Simple and Easy-to-Use Interface
The DP-008EX is designed for on-the-spot recording. No unnecessary features were included that might complicate the recording to ensure easy functionality. Designed with analog functionality and dedicated control knobs the DP-008EX POCKETSTUDIO is one of the simplest to use songwriting scratchpads on the market.
Ultra Light Weight Design
Carry It with you everywhere in your gig bag. The DP-008EX features ultra lightweight designs to ensure portability. It weighs in at only 360g (without AA batteries).
Two Analog Inputs for External Mics and Electric/Acoustic Guitar, etc.
The DP-008EX has two input terminals by phone-jack, these terminals provide to connect an external microphone, an electric-acoustic guitar and a line-level device like a synthesizer. Alternately with the help of a conversion cable you can connect a tablet device like the iPad (conversion cable is not included).
Record to SD/SDHC Card (up to 32GB), High-Speed Data Transfer via USB2.0
Both models record to widely available SD/SDHC card media (2GB card included). In addition, both models can connect to PCs via USB2.0 for high-speed data transferring. All song ideas can be transferred via USB or SD card readers to and from the units at any point in the recording process. Files can be used in correspondence with DAWs.
Two XLR Inputs with Full +48V Phantom Power
The DP-008EX can supply phantom power for condenser microphones, even when operated with AA batteries. (Notice: Operating time becomes shorter when used with phantom power supply.)
Grab Your Ideal Sounds with Insert Effects for All Inputs
The DP-008EX is designed with insert effects for all input channels. Insert effects include EQ, compressor, de-esser and exciter. For vocal recording, you can use the EQ to boost your desired frequency range, and compress your tracks to normalize your song.
2-Band Shelving EQ for Each Track
Demo song needs the same high-quality as final masters. The DP-008EX has separately adjustable 2-band EQ for each track. Hi-range EQ can be adjusted from 1.7kHz to 18kHz, Low-range EQ can be adjusted from 32Hz to 1.6kHz.
Ideal for Vocals, Acoustic Guitar, etc. Utilize the DP-008EX's Built-In Effects
The DP-008EX has six different types of reverb to help tailor your ideal sounding vocals to any style song. Easily set your reverb with dedicated control knobs for each track. Reverb effects include: Hall1/2, Room, Studio, Plate1/2. Reverb time and master level can both be adjusted.
Eliminate the Need for Any Other Products with Built-In Mastering Effects
The DP-008EX's built-in mastering effects will provide high-quality master-like file creation. The mastering effects include 2-band EQ, Multi-band compressor and Normalize effect. Finalize dynamic and powerful sounding songs by utilizing the DP-008EX's mastering effects.
The Auto Analysis Mastering Function Allows Easy Track Mastering
Anyone using the DP-008EX can easily master tracks with the Auto Analysis Mastering tool. In one step, select a mastering style, NATURAL or MAXIMUM, then the DP-008EX will make the calculation based on analysis of the song data.
Be prepared whenever inspiration strikes. Order the DP-008EX today.
DP-008EX Digital 8-Track Pocketstudio
Review Snapshot®by PowerReviews
Best Uses
Most Liked Positive Review
Great Product, Great Deal
This is a great little piece of equipment. It is small enough to take with you wherever you go. Turn virtually any space into a make shift studio. While there are better pieces...Read complete review
This is a great little piece of equipment. It is small enough to take with you wherever you go. Turn virtually any space into a make shift studio. While there are better pieces of equipment out there, for the price this one can't be beat.
If you are not familiar with recording, you should take the time and read the instruction manual very carefully. My 16 year old daughter was able to use the manual and have a multi-track song recorded in about an hour. It has great sound on the guitar tracks, but I would recommend picking up a condenser mic to go with it. The built in mics are sufficient for basic stuff, but the additional mic will help tremendously with achieving a professional sound.
You should know that the AC adapter is not included and the battery life is short lived to say the least. Be sure to pick up an adapter to go with the DP008EX and you will be good to go.
All in all this is a great product and I would absolutely recommend it to you!
Most Liked Negative Review
Improved 008
I got this as a SDOTD (with the TM78 microphone) for scratchpadding outside my digital studio. I was surprised at the depth of features and quality of the sound as well as the...Read complete review
I got this as a SDOTD (with the TM78 microphone) for scratchpadding outside my digital studio. I was surprised at the depth of features and quality of the sound as well as the decent internal microphones. The features have been substantially improved over the previous 008.
The construction is good (especially compared to the atrocious DR-08 I bought previously) and the controls are intelligently laid out. The manual is sensible and well-organized, which is important with a product with as many complex functions as this has.
The biggest single problem (in common with Tascam's other portables) is the extremely high battery consumption relative to Tascam's fanciful claimed battery life. This is a real deal-killer for outside use. Incredibly, given this unit's ravenous appetite for AAs (especially when providing phantom power) and its list price, there is no AC adapter included! What were they thinking?
At a very low sale price, I would recommend this unit, with the caution that there would be additional investments in multiple sets of rechargeable batteries and a wall adapter. At typical retail, I would not.
Reviewed by 27 customers
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Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
First of all, I'm not new to multitrack recorders. I have my main recorder in the studio, but I wanted something that was portable and powerful. I was immediately impressed by the build quality. This unit has some weight and feels like you'd expect a quality piece of gear to feel. The internal mics do a decent job of noise rejection and pick up surprisingly well. Having only 2 inputs is limiting, but hey for the price... The good news is that with bounce down recording you can actually have up to 14 tracks. The unit has some basic effects that are decent and can be applied either pre or post recording. The vocal effects and compressor do a good job. If you are familiar with a multitrack recorder the layout and basic recording will be familiar and intuitive. If you are not then the manual can be confusing. The mix down process is somewhat confusing and the manual takes some study. Now for the cons. The unit does not come with a power supply and battery life has not shown to be as long as advertised (surprise, surprise). The supply is five volt two amp, so it's not as easy to find a good generic. I don't know why companies can't just standardize a power supply to neg nine volts and be done with it. Just get a supply. Be prepared to spend some time with the manual and a little head scratching. Also, take the time to make some test recordings and play before recording something vital (I found out the hard way). I haven't used phantom powered mics yet, so I'm not sure of the battery draw there. Take extra batteries. Overall, I am thrilled with the recorder and the folks at MF always make shopping a pleasure.
Best Uses
Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
If you already have a Full Size studio recorder this thing is EASY to use. I had a little trouble down loading to a PC READ every WORD in the manual on Downloading.Final Mastering sounds GREAT!Once you get the Hang of this thing you WILL love it.Do yourself a favor GET the AC power for in the studio 6hr. Batt life goes Quickly when your Busy, But on Batt.go Mix in the livingroom. :)
Best Uses
Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
I found that I was able to use it right out of the box with just a brief run through of the manual. I, being of the cassette tape era and having owned another multi-track found it especially inuitive to navigate.
I've run direct and with the internal mic's at home with guitar and found the sound quality to be quite pleasing. I also use this at band rehearsal and with the right placement, adjustments to trim, output level, gain - that it captures a pretty balanced sound.
It's been two weeks that I've been using this device almost on a daily basis. I can't express how easy it is to use with just a short read of the instructions. It has many more functions which I've yet to explore but for recording on the fly this is very simple to use.
I've played some recordings for people who are your typical listeners and they can't distinguish between this and studio quality recordings.
For me, it's an all in one srcatchpad which has exceeded my expectations and is perfectly suited for what it was designed for.
Best Uses
Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
It's pretty much everything that Tascam says it is.
Great product. Fast and simple (esp. compared to recording software). The manual could have been written in a more concise manner, but when has that ever happened? Get the AC adapter.
Best Uses
Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
I have replaced my Teac Reel to Reels with the Tascam DP-008 and now added the EX Model. I record all my You Tube Covers and Guitar Instructional Videos using The Tascam DP-008 Recorder.I love these Units.
Best Uses
Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
I've been put through the wringer with paying for blocks of studio time to lay down vocals for tracks. With the DP008EX, I have taken that money I would have spent and put it to good use. Ive coupled the DP008EX with an MXL 990 Condenser Mic and, I now have a studio quality set up that is within my budget.
Best Uses
Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
I am an old geezer who has owned a 4-track cassette Portastudio for years (I still have it, and it still works perfectly!).
Around 14 years ago, I made the switch to Cakewalk and computer-based recording. While recording on a computer opens up an entire new world of possibilities, my productivity actually suffered -- any time I tried recording a new song, it seemed like I would spend too much time messing with computer stuff, and not actually recording. Then there's all the upgrades, patches, etc. Recording become less "fun" and more of a "chore".
I saw the DP-008EX on sale at Musician's Friend, and decided to give it a try. I was hoping that, by eliminating the computer, my recording would again become as easy and painless as in the old cassette Portastudio days.
The Digital Portastudio comes close, but has a couple of annoyances that get in the way of me truly enjoying it.
The recording is push-button simple. press the "record" button on a track, and press the master "record" button on the unit -- you're recording a track! In this regard, it works exactly like the old Portastudio does. Once you get your input sources set up properly, you can lay down 8 tracks with ease.
Sound quality is very good.
Super portable! You could record with this anywhere. I'm thinking of carrying it in my car along with a guitar, so I could record tracks on my lunch hour at work.
Bouncing tracks is done in "real time", which is wierd, but works flawlessly.
Unit allows you to Import/Export tracks to/from a computer, via the SD card.
I like the built-in Mastering mode, I wouldn't call the results "studio quality" but I am very happy with it.
The old cassette Portastudio's had a Mic/Line switch, and a trim pot, for each track, right on top of the unit. It was simple-easy to switch between a line or mic source, and set the trim. I switch between microphone, guitar, and a keyboard a LOT. On the Digital Portastudio - the Mic/Line switch is on the BACK of the unit, where you can't see it.. and there's only one switch that applies to all inputs. And there's no trim pot -- to set the input gain of the source, you have to go to a menu mode and select "Ext Input - MIC" or "Ext Input - Line" - this takes several button clicks. And you have to do it for each input (ie, twice). Because the switch and trim settings are "invisible", it's easy to forget where you're set and you'll mess up a few takes before you realize what the problem is. I switch between microphone,keyboard and guitar a LOT, and this is a major hassle for me.
EQ settings are too hard to get to, via the menu. I wish they had added a couple more knobs per channel for EQ, like the old Portastudio's had. I dislike the EQ menu so much, I just ignore it.
Unit only records 2 tracks at a time - I knew this, but it might be important to note. If you want to record piano and vocals simultaneously, you can do so -- but each track will be in mono. A workaround would be to run your mic and keys through another mixer first, then feed the stereo output into the DP-008EX.
Best Uses
Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
This recorder has so many features, I'm not going to get into them here (read the product page). I now actually use this unit as the main recorder attached to my full-sized mixer board in my home studio... It's that good!
How MF can sell this for the price they do absolutely blows my mind. It's simply an incredible value, really can't say enough about that.
Thanks once again to Musician's Friend as always, for carrying quality products and promptly answering questions I had regarding this unit before purchase!
Best Uses
Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
Nice sound quality, easy to use, instructions even for dummies like me.
Best Uses
Comments about TASCAM DP-008EX Digital 8-Track Pocketstudio:
Great price for an outstanding piece of high quality equipment. Worked first time!
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We are looking for any franchise location of a SUBWAY restaurant. These include stand-alone restaurants as well as locations that are a part of another facility.
For those that are not aware, SUBWAY is the largest chain of fast food restaurants in the world. Yes, even the mighty McDonald's has lost ground to this juggernaut.
For information about SUBWAY itself, please see the SUBWAY Corporate Site
To have your SUBWAY added to the directory you will need to provide the following.
Photographic Image of the SUBWAY location, with SUBWAY logo visible
GPS coordinates of the location
Variable - Location Type
Variable - Seating Available
Naturally, we would like to get your opinions about the location as well, like quality of the sandwiches, cleanliness, hours they are open. All of these are optional but helpful.
Naming your Waymark Listing: You may name your Waymark Listing anything you like within reason but it should provide some indication of the nature of the site. Consider adding a descriptive tag at the beginning of the name to further assist Waymarking participants to locate the Waymark.
As a guideline, the following is a suggested naming scheme for listings in this category: Subway - 1600 Pennsylvania Ave.
While you are free to create your own Waymark Listing name, using the suggested style may help people when they visit multiple Waymark locations.
As a suggestion for your visit log, please make every effort to supply a brief-to-detailed note about your experience at the Waymark. If possible also include an image that was taken when you visited the Waymark. Images can be of yourself, a personal Waymarking signature item or just one of general interest that would be of value to others. Sharing your experience helps promote Waymarking and provides a dynamic history of your adventures.
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Subway - YHZ, Enfield NS
in Subway Restaurants
The restaurant is located in the back of the food court on the ground level.
posted by: elyob
location: Nova Scotia, Canada
date approved: 11/23/2014
last visited: never
Subway - Whitney Point, NY
Subway by Route 81 exit in Whitney Point
posted by: ripraff
location: New York
date approved: 11/19/2014
Subway (Futurum) - Ostrava, Czech Republic
CZ: Malé Subway v nakupnim centru mesta Ostravy // EN: Small Subway in the shopping center of Ostrava
posted by: Olii05
location: Moravskoslezsky kraj, Czech Republic
date approved: 11/15/2014
Subway by Rail Trail - Vestal, NY
Subway Store # 29375 is right next to the Vestal Rail Trail on the Vestal Parkway.
date approved: 11/9/2014
Subway Washington Ave. - Endicott, NY
A store in the center of Endicott, near the EPAC Theater.
date approved: 11/8/2014
Subway Vestal Parkway - Vestal, NY
Subway on a service road off of Vestal Parkway. Near Vestal High school.
date approved: 11/3/2014
Subway - Glade Rd & TX 121 - Colleyville, TX
Subway #16239 is located at 3930 Glade Rd, Suite #109, Colleyville, TX. Phone is 817-868-9190.
posted by: QuarrellaDeVil
location: Texas
date approved: 11/2/2014
last visited: 11/2/2014
Subway - Colfax Ave. - Denver, CO
This Subway is located in a busy shopping center, just west of the state capitol.
posted by: bluesnote
location: Colorado
Albury Subway, NSW
Beside a 'suite' of non-food shops, and with a gym at the other end this Subway is in a good position for a quick feed when coming into Albury.
posted by: Grahame Cookie
location: New South Wales, Australia
Subway - Tully - Modesto, CA
A Subway in central Modesto on Tully Rd.
posted by: saopaulo1
location: California
date approved: 10/31/2014
Subway - Oakdale - Modesto, CA
A Subway in north Modesto on Oakdale.
Subway - Oakdale and Scenic - Modesto, CA
A Subway at Oakdale and Scenic in Modesto, CA.
Subway - Coffee - Modesto, CA
A Subway on Coffee in Modesto, CA.
Subway - Yosemite - Waterford, CA
A Subway on Yosemite in Waterford, CA.
Subway - Cross Timbers & Garden Ridge - Flower Mound, TX
Subway #57800 is located at 765 Cross Timbers (FM 1171), Suite 105, Flower Mound, TX. Phone is 972-355-6161.
date approved: 10/30/2014
last visited: 10/28/2014
Subway - US 82 - Gainesville, TX
Subway #10059 is located in the Great Lakes Center at 905 E Hwy 82, Gainesville, TX. Phone is 940-665-8100.
last visited: 10/31/2014
Subway Store #56002 - Medford, OR
This new Subway franchise is located in the new Northgate Plaza.
posted by: thebeav69
location: Oregon
date approved: 10/26/2014
Subway - Seal Beach Blvd. - Seal Beach, CA
A Subway in a busy shopping center.
Subway - Round Grove Rd & Uecker Ln - Lewisville, TX
Subway #58987 is located in the Vista Park shopping center at 291 E Round Grove Rd, Suite 165, Lewisville, TX. Phone is 972-315-1819.
date approved: 10/22/2014
last visited: 10/21/2014
Subway - Lincoln Ave. - Anaheim, CA
This is one of many Subways in the area.
date approved: 10/19/2014
Apalachin Train Station Subway
This Subway has a parking lot and a sitting area. It is right off of 434 in Apalachin.
Subway - Anaconda, MT
On East Park Street, this Subway is at the far eastern edge of Anaconda.
posted by: BK-Hunters
location: Montana
date approved: 10/12/2014
Subway - I-30 & Broadway - Garland, TX
Subway in the Broadway Plaza shopping center, 5970 Broadway Blvd, Garland, TX, just north of I-30.
date approved: 10/8/2014
last visited: 10/6/2014
Subway - Byford, Western Australia
A Subway in a small country township
posted by: blingg
location: Western Australia, Australia
Subway - Six Flags Drive - Arlington, TX
Subway #48791 is located at 916 Six Flags Dr, Arlington, TX. Phone is 817-385-5272.
date approved: 10/1/2014
last visited: 9/21/2014
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