C2PC Overview

FCC ID: XEU2703240

Cover Letter(s)

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FCCID_1227690

Jason Heimer Program Manager Government Systems Suface Solutions 400 Collins Road NE Cedar Rapids, IA 52498 319.295.0521 JJHeimer@rockwellcollins.com December 1st, 2009 Federal Communications Commission 7435 Oakland Mills Road Columbia, MD 21046 Subject: FCC Class II Permissive Change for FCC ID: XEU2703240 In this memorandum, I am providing details of modifications to the existing Rockwell Collins Model Number, 270-3240-020, FCC ID: XEU2703240, for consideration of Class II Permissive Change. Overview The Rockwell Collins Part Number 270-3240-020, has undergone a series of modifications, to improve receive performance, environmental durability and improve production assembly and maintenance. The part in the configuration which was Part 90 and Part 15 tested and certified has not been manufactured. However it is the intent that the changes described in this document for this part, will be the configuration that will be manufactured. The Part 270-3240-020 consists of: 2 x XR25 7TC Transceiver Circuit Boards (termed VRS1 and VRS2) Carrier Circuit Board Daughter Circuit Board Mechanical Assembly components RF Cables and Connectors Heatsinks External Chassis and covers In summary Transceiver modifications have been made to passive components to improve receive performance. Mechanical changes have been made to improve manufacturing, mechanical integrity, heat dissipation and maintenance. Photographs on internal components and changes are described in the following sections. Sincerely, Jason J. Heimer Program Manager Rockwell Collins


Transceiver Circuit Board Changes Photographs Figure 1 Transceiver Board Top without Shielding Figure 2 Transceiver Board Top with Shielding Figure 3 Transceiver Board Bottom Transceiver Board Schematic Changes

Update Reason Details First Rx RF LNA Optimised Optimised to improve Inter- Supply voltage altered. modulation performance. Second Rx RF LNA Optimised to improve Inter- Supply voltage altered, attenuation added. modulation performance. 455MHz Rx LNA Optimised to improve Inter- Supply current and transistor matching modulation performance. improved, attenuation added. 455MHz Rx IF Saw Filters Improve Receive Inter- Avoid interaction between SAW filters and replaced by Discrete Filters modulation performance active devices. Transceiver Board Layout Changes Update Reason Details Tx/Rx switch Incorporating modifications Minor tracking changes. from previous design on to PCB. 455MHz Rx LNA Incorporating modifications Layout changed to fit new circuit topology, from previous design on to to improve signal flow and input/output PCB. isolation. 455MHz Rx IF Saw Filters Incorporating modifications Layout changed for new circuit topology. replaced by Discrete Filters from previous design on to PCB. TX VCO Incorporating modifications Minor layout change for different sized from previous design on to parts in VCO. Replacing previous transmit PCB. path elements with new topology. TX VCSO To avoid radiated spurious. Minor tracking change.

Transceiver Board Mechanical Changes Update Reason Details Tx VCO RF Shielding extended Extended shielding to cover Improved screening & layout. Tx VCSO filtering and mixer. Carrier Circuit Board Changes Photographs Figure 4 Carrier Board Top

Figure 5 Carrier Board Bottom Carrier Board Schematic Changes Update Reason Details RS232 IC changed Manufacturing and 2 x MAX3243E replace 2x ISL4243EIRZ maintenance Addition 8 indicator LEDs Assist product maintenance Parts. 4 x SML1209-0ER-TR 4 x SML1209-0UG-TR GPIO Header lines removed 8 GPIO lines removed to allow for LED signals from daughter card Power Supply Filtering To improve Power supply Addition of ACM1211-102-2PL choke to filtering to meet FCC Part provide additional noise suppression on 15 class B. power lines. Grounding of all Mounting holes To provide improved transceiver grounding to chassis Carrier Board Layout Changes Update Reason Details Location of GPIO Headers Location moved closer to 401 and 402 moved from RF connector side changed side access cover of PCB to opposite board edge near access cover General Traces relocated to provide greater clearances between mechanical mounting holes

and traces Carrier Board Layout Changes Update Reason Details RF Connector Cut Out To facilitate production and PCB cut out, located under the RF maintenance connectors DSUB44 Cut Out To prevent physical PCB cut out, located under DSUB44 interference with the rubber seal of DSUB44 Updated Transceiver and Improve mechanical Added 2 Carrier to VRS2 Transceiver Daughter card mounting integrity, grounding and standoffs to replace above standoffs. assembly. Added new Carrier to VRS1 Transceiver standoff Moved location of the six Carrier to daughter board standoffs

Daughter Circuit Board Changes Photographs Figure 6 Daughter Board Top Figure 7 Daughter Board Bottom Daughter Board Schematic Changes Update Reason Details LED Signals Added New GPIO signals to control LEDs added, and unused GPIO signals removed Mounting Holes grounded Mounting holes grounded to provide improved Transceiver grounding

Daughter Board Layout Changes Update Reason Details Updates to reflect Schematic changes Daughter Mechanical Changes Update Reason Details RF Connector Cut Out Added RF Connector cut out added to improve assembly Location Change of Daughter to Mounting holes moved to Carrier Mounting holes due to updated Daughter board dimensions as a result of daughter board cut out.

Internal Mechanical Changes Photographs Figure 8 Internal Base showing Heatsinking

Figure 9 Internal with Carrier and Daughter Board Figure 10 Internal with Carrier/Daughter and Transceiver Boards

Internal Mechanical Changes Update Reason Details Updated Transceiver and Improve mechanical Removed two Daughter card to Transceiver Daughter card mounting integrity, grounding and standoffs. assembly. Added 2 Carrier to VRS2 Transceiver standoffs to replace removed Daughter card to Transceiver standoffs. Added new Carrier to VRS1 Transceiver standoff, using right angle standoff. Moved location of the six Carrier to daughter board standoff. Power Converter Heatsink Improve heat dissipation Added machined aluminium heatsink in from DC-DC Converter place of padded heatsinks. Heatsink retaining screws Improve heat dissipation Screws added to fasten heatsinks against and mechanical integrity chassis.

External Changes Figure 11 External Top

Figure 12 External Bottom External Mechanical Changes Update Reason Details Heatsink retaining screws Improve heat dissipation Screws added to fasten heatsinks against and mechanical integrity chassis. External chassis fins machined to allow for fastening of one screw.


Document Created: 2009-12-22 11:32:55
Document Modified: 2009-12-22 11:32:55
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