AN762 CCI Amp and LPF Project

Discussion in 'Homebrew and Kit Projects' started by K9VPR, Jun 13, 2019 at 10:54 AM.

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  1. K9VPR

    K9VPR Ham Member QRZ Page


    This is a porject I building now, a 180w an762 Motorola CCI amplifier I got off eBay built. Seems to work into a dummy load.

    I ordered a ptt rx-tx sense switch from Pacific Antenna qrp kits, then I'm using a ic-781 lpf from eBay,(seemed easier to work on with the schematic) with a rotary switch to provide 12v to open the lpf relay I want to use.


    Attached Files:

  2. W9GB

    W9GB Ham Member QRZ Page

    RF-sense switching for external linear amplifiers ... was never a good idea.
    It entered “folk-lore” status during the 1970s CB era ... as illegal amplifiers were widely produced for 5 watt CB radios that did not have external T/R contacts.
    Direct switching — properly Sequenced — is the best approach.

    Jim, W6PQL (retired HP Engineer) offers a variety of parts for the DIY amplifier builder.

    Relay Sequencer, featuring a Transmit Inhibit feature for the Yaesu FT-817.
    The AN-762 is in reference to the Motorola Application Note #762 (AN762)
    written by Helge O. Granberg, K7ES (SK, 1996)

    AN-762 Construction Hints
  3. K9VPR

    K9VPR Ham Member QRZ Page


    Thanks I really didn't know much about the rf sensing part of it. If I use key in on the relay that would be good though, it would switch over before the tx?


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