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Help with Icom IC-765, output issues and more

Discussion in 'General Technical Questions and Answers' started by W4AJF, Jun 17, 2021.

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  1. W4AJF

    W4AJF Ham Member QRZ Page

    Hi all, hoping someone can help with an IC-765 I just received, it has 2 issues:

    Issue # 1:: No TX or RX on 160M (1.8mhz)

    Issue #2: Low and varied output on all other bands (receive is fine):

    TESTED in FM mode in to dummy load, CPU has been reset,tuner OFF, RF output control turned all the way up

    1.8mhz 0 ( mentioned)
    3.5mhzz 58 watts
    7mhz 60 watts
    10mhz 90 watts
    14mhz 40 watts
    18mhz 45 watts
    21mhz 40 watts
    24.5mhz 35 watts
    28mhz 30 watts

    I am hoping someone is familiar with the IC-765 and is familiar with this problem so can tell me specifically which board(s) to check or possible adjustments.

    Thanks,

    Adam Farber W4AJF
    Cooper City, FL
     
  2. W1NB

    W1NB XML Subscriber QRZ Page

    Adam,

    Without knowing what test equipment you have and your repair skill level it’s hard to give you any specific direction. Below is a high level block diagram of the radio between the RF unit and the antenna. I suggest testing the output directly out of the RF unit to see if the amplitude is in spec and flat across all bands. If so, move on to the first section of the antenna switch unit, then the tuner unit, then to the second section of the antenna switch unit. It’s best to test with an adequate bandwidth oscilloscope with a 10x probe so that you don’t load the stage under test. Start with the radio in AM mode and power reduced to a few watts, and look for amplitude flatness across bands. It’s likely that the low power and band to band flatness is related, if not the same issue.

    46FA3B71-2E47-4FE6-A7E1-D17A96E5716F.png
     
  3. W4AJF

    W4AJF Ham Member QRZ Page

    Hi, I really appreciate the post. This is way out of my skill level. I am handy and not afraid to try but I don't even know how to test output from the RF unit for example. Thanks, Adam W4AJF
     
  4. KG7WGX

    KG7WGX XML Subscriber QRZ Page

    Send it in for repair.
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    IC-765 hasn’t been made in decades, Icom certainly won’t touch it.

    Independent repair guys might.
     

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