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Removing Resister R3 from the TRF7960A EVM

Amir Phillips
Prodigy 20 points
Other Parts Discussed in Thread: TRF7960A

Greetings,

I am connecting an edge mounted SMA connector to the TRF7960A EVM for an external antenna and needed some clarification as to how to exactly "remove" the resister R3. Also do you all have a specific model for the SMA connector that is advised to solder on. Also could someone please provide some clarity to the comments, "At no time should resisters R4 and R5 be placed simultaneously." 

The reference pages that my inquiry comes from is the TRF7960A EVM User Manual pages 14-17 under Hardware Description.

www.ti.com/.../slou192c.pdf

Thanks in advance for of your help.

Best Regards,

       A

  • 0
    TI__Mastermind 29105 points

    Hey Amir,

    You just need to unsolder it using a soldering iron.  

    Amir Phillips said:
    "At no time should resisters R4 and R5 be placed simultaneously." 

    This is because it would connect both antennas to the 50 ohm point.  This will interfere with communication and could possibly damage the TRF79xx.  You can look at the full schematic but I've also captured this section for you here:   

    Typically, you would only populate either R3 or R4 to choose between the on board antenna or an external.  R5 is there to allow us to tune the onboard antenna through the RF test point.

    Thanks,

    JD

  • 0 in reply to JD Crutchfield
    Prodigy 20 points

    Greetings JD,

    Thanks for the prompt reply, all of your help is deeply appreciated. I understood that it needed to be unsoldered. I should have been a little more specific. I was asking the exact method someone from your company would recommended that would not damage the board. (hot air iron, chisel tip, pencil fine tip, ect.) No worries, I found someone who specializes in SMD Soldering and they have assisted me with that. I also appreciate the clarification on the R4-R5 situation as well.

    Thanks

    Amir 

  • 0 in reply to Amir Phillips
    TI__Mastermind 29105 points

    Great to hear you got it off.  Let me know if you have any more questions.

    Thanks,

    JD