Motorola M12 Oncore User's Guide download pdf (Page 26)

Chapter 3 – Receiver Description

Motorola GPS Products - Oncore User’s Guide

PCB Mounting

Hardware

ONCORE RECEIVER MOUNTING INSTRUCTIONS (GT+/UT+ ONLY)

Mounting Hardware Design Guidelines

For all the design validation and process validation tests that were conducted and

completed successfully by Motorola, the Oncore PCBs were mounted on round or

hex female threaded metal standoffs and screwed/tightened down with metal english

or metric screws. The mounting standoffs are available with english or metric

threads.

One of the key points in selecting the four standoffs that will mechanically hold and

secure the Oncore PCB to the application PCB directly or indirectly is the diameter of

the standoffs. Obviously the height of the standoff will be determined by the

customers application. Recommended nominal diameter of the standoffs should be

around 0.165 in. or 4.16 mm (See Figure 3.8).

These standoff should give ample space and clearance between

the outside diameter of the standoff and the outside edge of the RF shields of the GT

Oncore, and

the outside diameter of the standoff and the outside edge of the 10 pin header of the

GT Oncore.

If the recommended diameters of the standoff are not available, one can probably go

higher with the next available diameter. See the following table for a suggested list of

companies that carry standoffs equal or close to the recommended diameters. The

maximum limit is around 0.212 in. or 5.38 mm diameter; at this point the standoffs are

literally touching the RF shields of the Oncore.

Another important point to consider is the mating 10-pin receptacle on the application

PCB. When choosing this mating connector, one must be aware that the outer

diameter of the standoffs should not come too close to this connector.

Obviously the height of the standoffs will be determined by the components that

are populated on the application PCB, especially the height of the 10 pin receptacle.

See Figures 3.9 and 3.10 for recommended layouts of the standoffs and mating

receptacles. Also see Figure 3.5 which is an outline drawing of the Oncore receiver.

The drawing describes the overall placement and height of large components and

connectors populated on both sides of the Oncore PCB.

Revision 5.0 08/30/02

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Motorola M12 Oncore User's Guide Page 26