Condition: Used

This Spectrum Instruments TM4-M+ Rubidium Time and Frequency Reference System (part number 21351-102) is in excellent used condition with minimal usage signs. The unit has been tested in-house and confirmed fully functional, with the following results recorded:

• Almanac Status: OK
• Correct time acquired
• Phase lock confirmed
• Oscillator mode: 4
• Satellites tracked: 5
• Clean 10.000 MHz (100.00 ns period) output verified

These results were achieved under less than ideal GPS conditions, demonstrating the quality and stability of this unit.

Included in the sale:
• Spectrum Instruments TM4-M+ Rubidium Time and Frequency Reference System (21351-102)
• GPS antenna with cable
• USB cable (JDSU P/N 21130024)
• Coaxial cables (various types, including JDSU P/N 80-30662-01)
• BNC and RF adapters
• USB adapter
• Power cable
• JDSU branded soft carry case

The images provided are of the actual item you will receive. Please review them carefully for the cosmetic condition and what is included in the sale.

The Spectrum Instruments TM4-M+ is a Rubidium Time and Frequency Reference System designed for precision synchronisation, frequency calibration, and distribution in laboratory, telecoms, and field environments. The unit combines a rubidium atomic oscillator with GPS receiver disciplining to deliver a highly accurate, traceable reference output with excellent short- and long-term stability.

The GPS-disciplined rubidium oscillator ensures the output remains locked to UTC, making it suitable for standards laboratories, calibration benches, communications test systems, and any application requiring a traceable 10 MHz reference signal. The system is capable of maintaining phase lock even in challenging GPS reception environments.

Key Specifications:
Model: TM4-M+ (Part No. 21351-102)
Manufacturer: Spectrum Instruments
Oscillator Type: Rubidium atomic oscillator
Disciplining: GPS-disciplined
Reference Output: 10.000 MHz
Oscillator Mode: GPS-disciplined (mode 4)
Connectivity: USB interface, coaxial RF outputs
GPS Input: External GPS antenna (SMA/BNC)
Form Factor: Portable / rack-adaptable
Applications: Frequency calibration, standards laboratories, telecoms synchronisation, precision timing

Please refer to the Spectrum Instruments manufacturer website for full and up-to-date specifications.

Shipping & Returns Policy

Shipping Policy

• Processing Time: Orders are typically processed and dispatched within 1 business day.
• Shipping Methods: We offer Expedited Shipping to all destinations using UPS/DHL/Fedex/Royal Mail and other reputable carriers.
• Shipping Times: Mainland UK: 1-2 Business Days / Mainland Europe and USA: 2-3 Business Days / Rest of the World 5-7 Business Days.
• Shipping Costs: These are calculated at checkout based on the shipping method, destination and package dimensions.
• CUSTOMS AND TAXES: It is YOUR responsibility to liaise with customs in your country and ensure your package is cleared and any taxes are paid.
• Shipping Destinations: We ship worldwide.
• Tracking: Once your order is shipped, we will provide you with a tracking number via email.
• Insurance: All shipments are insured. In case of damage, please contact us via email within 48 hours of receiving the product with photographic evidence, please also ensure a report is logged with the delivery driver.

Returns Policy

• Return Period: In the event of an item being received which is not as specified, you can return your purchase within 14 days of delivery.
• Condition of Items: Items must be returned unused and in their original packaging.
• Return Method: All returns must be notified in writing to hello@ttinstruments.com, and the email should include the order number, date and reason for return within 14 days of delivery.
• Restocking Fees: A restocking fee of up-to 20% is applicable for items returned for any reason other than not as specified.
• Refund Method: Refunds are processed to the original method of payment within 5 business days of receiving the return.
• Exchanges: We do not offer exchanges. It will either be a replacement or a refund.
• Return Shipping Costs: Return shipping costs will be borne by the customer unless the item is not as specified, in which case we will arrange a prepaid return label.