New antenna (Tram 1185) - Cannot hear repeater

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KC3FGX, Jul 13, 2016.

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  1. KC3FGX

    KC3FGX Ham Member QRZ Page

    Hi all,

    I'm having some trouble as a new ham with my UV-5R. I purchased an Expertpower 7.5in whip antenna for my radio a few months back and it performs fine with being able to hear my local repeater (VHF) 5 miles away. I can't transmit reliably from my location, but that's not my current concern. I purchased a Tram 1185 for use on my car, and wanted to test it from my inside my home location.

    I have 2 UV-5Rs...one with the Expertpower antenna and the other with the Tram 1185 hooked up via an SMA to UHF cable. With the Expertpower, I can hear talk on the repeater just fine, but with the Tram I hear nothing at all. I also switched the antennas to make sure it wasn't my radio. Can anyone help me understand what might be going on?

    Thanks.
     
  2. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    Do you have a ground plane under the antenna?


    If your receiver is being overloaded with off-frequency signals, it will be silent. I've heard this is a common problem with that radio but can't confirm it myself.

    If you are trying it indoors, it may be receiving strong interference from things in the building. This is very common.
     
  3. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    If the antenna looks like it does in pictures online, it might not work at all on 70cm.
     
  4. KC3FGX

    KC3FGX Ham Member QRZ Page

    Hi thanks for the reply. I don't think I have a ground plane under it (I had to Google for what that is). I'm not worried about the radio as the radio with the other antenna works just fine for receiving. So I suppose I should try testing this on my car rather than in my home?

    Also, the repeater is a 2M repeater, not 70cm, so I'm not too concerned about that yet. On a side note, the Tram 1185 is a 19" antenna.
     
  5. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    OK. A ground plane is necessary for that type of antenna. It could be your car roof or a cookie sheet or pizza pan.

    The radio works well with the stock antenna because the stock antenna is extremely lossy. The radio is designed with that in mind. So it has lots of receiver gain.

    I don't know thought about the Expertpower antenna to say it isn't different than the stock one.

    When you connect an antenna that receives more signal, the high gain causes overload. This is the reported problem with that radio.

    You can try to determine if this is what's happening by attenuating the signal. What I would do is:

    Put the antenna on a ground plane, even your stove top. Put the other one on the other side of the room as a reference.
    Disconnect the Tram antenna from the radio.

    Hold the antenna connector near the connector on the radio. Very close, but not touching. Slowly increase the distance, whilst the reference radio is receiving a signal.

    If you do hear something at some distance, but not when the antenna is actually connected, the first possibility is that the antenna is shorted. The second is that the receiver is being overloaded.
     
  6. KC3FGX

    KC3FGX Ham Member QRZ Page

    Awesome, thanks, I'll give this a shot once I get home today.
     
    KC9UDX likes this.
  7. KC9UDX

    KC9UDX Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    It's also entirely possible that your new antenna is defective.

    Try that first.

    If you still don't receive anything at all, you'll need to determine if the Tram is an open circuit or a short.
     
  8. KC9ZHR

    KC9ZHR Ham Member QRZ Page

    I get so much interference inside my house at 2m&70cm that an indoor antenna is almost useless.....tv's, computers, CFL bulbs, etc. The worst is the RFI from HDMI cables. YMMV
     
    KC9UDX likes this.
  9. KF5FEI

    KF5FEI Ham Member QRZ Page

    I would check the adapter / adapter cable you use between the Tram antenna and the UV-5R -- those are usually not built very well, and if they are open or shorted, you would not hear anything. If you put your Expertpower antenna on your other UV-5R, does the radio work OK?
     
  10. W4JFA

    W4JFA Ham Member QRZ Page

    I would start with checking the SWR on the Tram. Someone above mentioned the Tram could be defective, someone else mentioned the adaptor cable could be defective. I agree that's possible. The SWR test is the place to start.
     
  11. KA9JLM

    KA9JLM Ham Member QRZ Page

    I use a cookie sheet in the morning and a pizza pan at night.

    A car roof is good but it takes a lot of coax to reach the parking area.

    Plus my neighbor don't like me putting my antenna on her car. :oops:
     
    KC9UDX likes this.

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