Icom R-71a antenna input question

Discussion in 'General Technical Questions and Answers' started by WHICKSPAR, Nov 27, 2019.

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  1. WHICKSPAR

    WHICKSPAR QRZ Member

    My Icom R-71a has two small ceramic disc capacitors shunted to ground on each of the two antenna connectors. These capacitors don't appear on any of my schematics. Does anyone know the purpose or actual ratings for these capacitors? They are very small, size of a pea, and have 33 on them. I am assuming this must be 33 pf. owing to their small size. I am replacing the electrolytic capacitors and broke the lead on one of these small capacitors.
    Any help would be appreciated.

    Wayne Hicks
    Austin, Tx.
     
  2. N5RFX

    N5RFX Ham Member QRZ Page

    You have to look at the correct schematic.

    upload_2019-11-27_12-6-15.png
     
  3. N5RFX

    N5RFX Ham Member QRZ Page

    These are 33pF 50V ceramic capacitors. One quick check to make is to use a DC voltmeter and check the voltage between the center pin and ground of the SO239 antenna connector. It should measure near 0V. If it measures somewhere around 6 volts, the receiver has had an overload on the input.

    Mark N5RFX
     
  4. WHICKSPAR

    WHICKSPAR QRZ Member

    You are sooooo right! I never noticed this overall schematic. I have looking at individual board schematics. Thanks for the help.
     

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