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Thread: EFJohnson 5100 not outputing full RF power?

  1. #1
    Michaeldim No Longer Registered

    Default EFJohnson 5100 not outputing full RF power?

    I have a UHF 380-470 EFJohnson 5100 that I bought recently. At first, the radio worked fine, but recently it seems to have developed an odd issue. It would seem that the RF power output is low despite the power setting being high. I found that I could no longer access repeaters from my house. I initially surmised that this was an issue with the repeaters, but my cheap chinese radio (with the same 4 watts specified) was able to reach them with ease using the same antenna.

    I went on to assume that the issue was with the settings on the radio's codeplug. I verified the frequencies and CTCSS tones being used in the settings as correct and confirmed that the radio was outputting them correctly with my scanner. I went on to write an entirely new codeplug and that did not solve the issue.

    I suspected that there was a problem with the power output. Without specialized tools, the best way I could test was to compare how far away the radio could be heard by my scanner without an antenna attached to the scanner. The 5100 could only break squelch from about three feet from the scanner at high power setting. Comparatively, the chinese radio with the same antenna would open the scanner's squelch from across the room with ease.

    I allowed the charging unit to condition the battery to confirm that it was not the issue. The radio behaves normally otherwise.

    My experience with commercial hardware is limited to my brief time with this unit. I have no tools to verify my assumptions and these are only the most logical conclusions I could draw.

    The radio is running Firmware v4.4.16. I know this is not the most current firmware for this model. If anyone could tell me how to go about acquiring the most up-to-date firmware, I'd be appreciative. Additionally, any other help or thoughts will be greatly appreciated. I hope to resolve this issue without expense.

  2. #2
    Join Date
    Jul 08, 2012
    Thanked 99 Times in 34 Posts
    Country: United States


    It is possible that the finals in the radio are fried, especially if you are saying you are not able to hear the radio on your scanner past three feet away. The easiest way to tell is to get a dummy load and a power meter to verify the output of your radio. If you have any friends that are hams you might try asking if they could verify power output for you. You might try looking up local ham radio clubs and visiting one of their meetings with your radio as I am sure someone would have the equipment and would be more then happy to check it out and try and recruit you. Or, if you plan on being involved in radio for any appreciable amount of time a dummy load and watt meter would be a wise investment.

  3. #3
    Join Date
    Mar 01, 2012
    Houston, TX
    Thanked 193 Times in 84 Posts
    Country: United States


    I would concur, either a PA or driver failure.