Quartz crystal resonators play an important role in ensuring the precision and stability of frequency control and timing devices, like oscillators. Among the many standards that govern these components, MIL-PRF-3098 is as a key specification that defines the performance, design and testing requirements for quartz crystal resonators used in high-reliability and military applications. In this blog we give an overview of MIL-PRF-3098 and explain the importance of Qualified Parts List (QPL) quartz crystal resonators in military radio frequency and microwave systems.
MIL-PRF-3098 Overview
MIL-PRF-3098, short for Military Performance Specification for Quartz crystal resonators, Oscillator, Quartz (General Specification), is a standard developed by the United States Department of Defense. This specification outlines the stringent requirements that quartz crystal resonators must meet to be deemed suitable for use in aerospace and defense applications. These applications can range from communication systems and radar equipment to guidance systems for missiles and other critical electronics.
The purpose of MIL-PRF-3098 is to provide a range of standard crystals that can be selected for military or high reliability use and to ensure the reliability, stability, and overall performance of those standard crystals. This performance specification addresses the environmental and operational requirements which approved crystals must meet and describes the qualification process in order that a manufacturer can become an approved supplier. The specific crystal types and requirements are detailed in numerous individual type specifications which are referred to as “slash sheets”. For example MIL-PRF-3098/104 provides a detailed specification for 5th OT AT-cut crystals in an HC-35 enclosure with frequencies from 50 to 125 MHz. There are many specification sheets available which afford the user community a wide range of crystals to address design requirements from 1 to 125 MHz
Key Parameters:
- Frequency Tolerance and Stability
MIL-PRF-3098 establishes strict limits on the permissible deviation of the quartz crystal resonator’s output frequency from the specified nominal value across temperature and at specified load conditions and drive levels. This is critical in applications where precise timing is essential, such as in communication systems. - Aging Characteristics
Quartz crystal resonators used in military applications must exhibit minimal frequency drift over time. MIL-PRF-3098 defines aging characteristics to ensure that quartz crystal resonators maintain their stability over extended periods, contributing to the longevity and reliability of radio frequency and microwave systems. - Environmental Testing
Harsh environments can subject electronic components to extreme conditions, including wide and rapid temperature variations, humidity, shock, vibration and other mechanical stresses. MIL-PRF-3098 qualification ensures that the manufacturers crystal designs and manufacturing processes are able to produce quartz resonators that will remain within specification limits and which will operate reliably when exposed to these challenging conditions.
Ensuring MIL-PRF-3098 Compliance
One of the key aspects of MIL-PRF-3098 is the creation and maintenance of the Qualified Parts List (QPL). The QPL is a comprehensive list of quartz crystal resonators that have undergone thorough testing and successfully met all the requirements outlined in MIL-PRF-3098. Inclusion in the QPL is a testament to a quartz crystal resonator’s reliability and compliance with the stringent standards set by the military.
Advantages of Using QPL Quartz Crystal Resonators:
- Reliability
QPL quartz crystal resonators are proven to meet the high standards of MIL-PRF-3098, providing a level of reliability that is crucial in military applications where equipment failure is not an option. - Consistency
The QPL ensures consistency in the performance of quartz crystal resonators, allowing for easier integration into complex military systems without the need for extensive customization or tuning. - Compliance
Aerospace and defense manufacturers can confidently select quartz crystal resonators from the QPL, knowing that these components adhere to the specific requirements of MIL-PRF-3098. Parts marked with the MIL-PRF-3098 part number come from a qualified supplier and have received the specified Quality Conformance Inspection testing prior to shipment.
Challenges and Considerations in Implementing MIL-PRF-3098
While MIL-PRF-3098 and QPL quartz crystal resonators set a high standard for military-grade components, there are challenges and considerations that engineers and manufacturers must navigate.
- Cost
Achieving compliance with MIL-PRF-3098 and obtaining QPL certification can involve additional testing and quality control measures, leading to higher manufacturing costs. Balancing performance and cost are important considerations for defense programs with budget constraints. - Customization
Some military applications may require quartz crystal resonators with specific characteristics that go beyond the standard requirements of existing QPL crystals. In such cases customization may be necessary but parts based on MIL-PRF-3098 and purchased from an approved supplier will assure the same level of reliability and performance as a QPL part. - Supply Chain Management
Maintaining a stable supply chain of QPL quartz crystal resonators can be challenging due to factors such as limited suppliers and fluctuations in demand. Military contractors must carefully manage their supply chains and select suppliers that can ensure a consistent and timely procurement of qualified components.
Conclusion
As radio frequency and microwave technology continues to advance, suppliers of mission-critical components must evolve accordingly. MIL-PRF-3098 is not static, and periodic updates may be introduced to address emerging challenges and leverage technological advancements. Additionally, the scope of QPL quartz crystal resonators may expand to encompass new applications and industries where stringent performance standards are required.
In conclusion, understanding MIL-PRF-3098 and the significance of QPL quartz crystal resonators is important for anyone involved in the design, manufacturing, or procurement of military-grade frequency control and timing components. The strict requirements set by this specification ensure that quartz crystal resonators used in critical defense applications meet the highest standards of reliability and performance, contributing to the safety of men and women in the armed forces.
Quantic Croven has been continuously approved to MIL-PRF-3098 since 1967 and has a wide range of QPL certified crystals available for general use and also provides custom designs based on specific customer needs.
Authored by:
Luke Mueller, Managing Director
William Walsh, Marketing & Communications Manager