2m mobile wiping out XM roady mobile mag-mount antenna?

Discussion in 'Mobile Radio Systems' started by WA7ARK, Jun 17, 2020.

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  1. WA7ARK

    WA7ARK Ham Member QRZ Page

    I am using a Delphi Roady XT with the small mag-mount amplified Sat antenna to be placed on the vehicle roof. How far should it placed from a two-meter mobile transmit antenna (1/4wl whip; radio runs ~45W)?

    The XM antenna died recently. I am wondering if RF overload from the 2m rig might have killed it?
     
  2. KC7YRA

    KC7YRA Ham Member Volunteer Moderator QRZ Page

    While I cannot say for absolute certainty that your 2 meter rig didn't cause the damage, I will say that I've had those little XM magmounts since XM first started as a company. Even with HF and VHF/UHF mobile stuff up to and over 100 watts, I never had one fail.

    By anecdotal evidence makes me think the antenna just failed and was not influenced by your 2 meter rig.
     
    WA8FOZ and K0UO like this.
  3. AI3V

    AI3V Ham Member QRZ Page

    Classic case of common mode.

    Try a choke right at the base of the antenna, and be sure to attatch the coax to a ground rod right before it attatches to the rig.

    Rege
     
  4. WA7ARK

    WA7ARK Ham Member QRZ Page

    Negative Rege, blocking common-mode on the feed line to the XM patch antenna or the 2m whip antenna would make them work better, thus more likely that the XM antenna gets wiped out.;)

    I did pry the lid off and look inside the dead one. There are at least 4 transistors, several diodes, and what looks like a MMIC. The dead one draws about the same current (~50mA@5V via a bias-T) as the new one. I relocated the new one further from the 2m whip....
     
    K0UO likes this.
  5. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    Honestly I've never had one fail and I run high power in various mobiles, all with XM.
     
  6. KD4UPL

    KD4UPL Ham Member QRZ Page

    My 1/2 wave 2m antenna is about 18" from my satellite radio antenna. It's been that way for about 10 years. I haven't had any problems with the antenna. My rig will only run 50 watts. I don't know what a higher powered radio would do.
     
  7. WA7ARK

    WA7ARK Ham Member QRZ Page

    It might have been coincidence, but the new XM antenna is working fine. I increased the distance from the 2m APRS antenna because I could....
     
    K0UO likes this.

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