1. Frequency:
Frequency is specified in Hz (base unit), Khz (Hz x 1,000), or Mhz (Hz x 1,000,000). M H Electronics manufactures AT cut crystals from 980 Khz to 150 Mhz.

2. Mode:
AT cut quartz resonators can vibrate on many frequencies simultaneously. The lowest frequency that the crystal can operate at is called the fundamental mode. Higher frequencies are achieved by operating the crystal on odd multiples 3rd, 5th, etc called overtones.
The following is an approximate guide line for mode versus frequency.
Fundamental mode 960 Khz to 30 Mhz
Third overtone 18 Mhz to 100 Mhz
Fifth overtone 60 Mhz to 150 Mhz

3. Calibration (adjustment) tolerance:
This is the maximum allowable deviation of frequency at a given operating temperature, typically 25C. Calibration tolerance is specified in either PPM (parts-per-million) or percentage. Typical values are between 10 PPM (.001%) and 50 PPM (.005%).

4. Calibration temperature and tolerance:
A. Ambient type: Crystals operating at 25C ambient are said to be "room type" crystals. Frequency versus temperature is specified in PPM or percentage typically between 5 PPM (.0005%) and 50 PPM (.005%) with a minimum and maximum operating temperature. Typical ranges -40C to 0C on the low range and + 50C, to +70C on the high range.

B. Heated type: Other crystals are operated in an oven environment at a fixed temperature between 60C and 85C, these are said to be "oven type". Most ovens operate at 65C, 70C or 75C

C. High stability: We manufacture a high stability crystal unit. The HS-4 is a self contained stabilized crystal. Please see our HS-4 page for further details.

5. Load factor ( load capacitance): This is sometimes specified as CL. The load factor is the dynamic load of the total circuit measured at the crystal socket or printed circuit pads. There is no physical difference between series and parallel resonance crystals. The difference is only in the calibration of the crystal. The frequency adjustment of the resonator in circuit is accomplished with either a capacitor an inductor or both.

A. Series resonance: Crystals operating at series resonance appear resistive in the circuit. This is sometimes specified as FS.

B. Parallel (Anti-resonance): Crystals operating in the parallel mode appear inductive in the circuit. This is sometimes specified as FL. Typical load capacitances range from 13 to 50 pF. Values outside this range may be used. Some standard values are 13, 20, 24,30, and 32 pF Some design considerations of this factor are the greater the LC the less pullability or trim sensitivity (TS [specified in PPM/pF] )

6. Shunt capacitance:
Also known as static capacitance or CO. This is the sum of the capacitance of the electrodes, holder, and leads, measured lead to lead. Typical values range from 4 to 7 pF. Values outside this range may be used. Some design considerations of this factor are pullability or trim sensitivity (TS [specified in PPM/pF] ) and phase noise. Usually the greater the CO the more pullability and the greater the potential for phase noise.

7. Drive level:
Drive level is a measurement of the total power dissipated through the crystal operating in the circuit. Typical drive levels are between 50 uW and 1000 uW (1 mW) Values outside this range may be used. Drive levels should be kept at the minimum level that will initiate and maintain oscillation. Excessive drive may cause correlation difficulties, frequency drift, spurious emissions, "ringing" wave forms, excessive ageing, and/or fatal structural damage to the crystal.

8. Resistance:
Also know as equivalent series resistance (ESR) or activity. This is the maximum allowable resistance of the crystal. Some design considerations of this factor are ease of starting and drive level to sustain oscillation. The lower the ESR the greater the Q and the less drive level required to oscillate the crystal. We use Mil C-3098 (US military specifications) as a guideline for these specifications unless otherwise stated.

9. Holder style:
A wide variety of holders are available to meet your particular requirements. Some design considerations of holder styles are space limitations, mechanical board placement. Please refer to our holder page for the recommended frequency limitations on various holders. If you require a holder not shown please feel free to contact us with your requirements.

10. Ground wires / Third leads:
A wide variety of welded ground wires or third leads are available. Shown on our ground wire page are some of the lead configurations that we currently make. Some advantages of a third lead are superior mechanical stabilization, RF drain, surface mount configuration, tape reel dispensing. If you require a style not shown please feel free to contact us with your requirements.

11. Special requirements:
There are many other specifications for crystals not mentioned above. We use Mil C-3098 (US military specifications) as a guideline for these specifications. If you have special requirements please contact us. Some of these may include specifications for shock and vibration, motional inductance, motional capacitance, extended operating temperatures, trim sensitivity (TS [specified in PPM/pF] ), and matched pairs/sets (temperature versus frequency) of crystals.

12. Insulators:
When "shorting" issues are a problem we have solutions. We have insulators for the lead end of most crystal holders where the metallic base is in close proximity to circuit board traces. We have a polyolefin sleeve that can enclose the entire crystal case where the crystal body is to be placed base is in close proximity to circuit board traces or other components. Please see our insulator page for further details.

For more details on ordering, please go to our request for quote page .

9569 9th Street Rancho Cucamonga, CA 91730

International + (909) 989-1976 Fax (909) 945-4971