Thread: Sorting out a RX issue with a VX-7R...

  1. #1
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    Default Sorting out a RX issue with a VX-7R...

    I think I have narrowed down my issue but just looking for a little confirmation...

    I volunteer as a first responder at a ski area that uses commercial HTs on 152.450 and 157.710. When I'm not on duty with one of the provided radios but still on-site, I have used my VX-7R just to monitor what is going on (in case they may need extra help in the treatment room). Lately, when compared to the provided radios, RX has static and I only catch ~50% of the transmission, if at all. This issue seems to coincide with the area switching to narrowband to meet the FCC deadline.

    I've tried to do some research but haven't come up with a great single reason for my problems. I reprogrammed to 12.5kHz then 5kHz steps with no improvement. I do not have an antenna specifically tuned for the 150mHz band, but I have considered it. The specs of the radio show TX/RX in the 144-148mHz range. I am getting the sense that the VX-7R with dual band rubber duck wasn't a great solution to monitor those frequencies to begin with, but it worked. Now with the switch to narrowband, it is struggling to pick up those transmissions at all so new/different hardware specific for commercial use may be needed.

    Does this make sense? I'm relatively new to the HAM/radio world and this is one of my first experiences troubleshooting. Would an antenna more specific to 150mHz solve my issues or do I need a different radio?

    Thanks!
    Last edited by zuren; 01-07-2013 at 08:38 PM.
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  2. #2
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    An antenna tuned to the proper frequency should help. That said, since you are not transmitting on the 15X.XXX frequencies, switching you radio back to wide band may improve reception as well.

  3. #3
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    Quote Originally Posted by GlennA View Post
    An antenna tuned to the proper frequency should help. That said, since you are not transmitting on the 15X.XXX frequencies, switching you radio back to wide band may improve reception as well.
    Agree on both counts. I replaced the stock rubber ducky on my VX-7R with a longer one from Diamond (don't remember the model number and I'm currently away from that radio) and a home-made "tiger tail" counterpoise and it improved both Tx and Rx range considerably, but I rarely use anything else than the standard 2m freqs.
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  4. #4
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    Quote Originally Posted by zuren View Post
    I've tried to do some research but haven't come up with a great single reason for my problems. I reprogrammed to 12.5kHz then 5kHz steps with no improvement.
    The steps is for tuning frequencies in VFO mode. What you need to do is set each Ski frequencie into a memory channel and set the modulation to NFM (narrow FM). When a memory is set to FM it is actually Wide FM. That should help. A good quality antenna will also help.
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  5. #5
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    I have never used the VX-7 but I can tell you that if it is looking for a wide signal and the signal in Narrow you will get poor RX performance. If your radio can be set to narrow by channel that is your solution. I doubt anything you can do with the antenna will improve things if this is set wrong. If the radio will not do it there are many that can and I would advise trading it out.
    To reemphasize what others have said, this is not about channel spacing or VFO steps. "Narrowband" is a modulation method. The radio needs to be able to do it.
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  6. #6
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    Here are the instructions for selecting wide vs narrow

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  7. #7
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    ^^
    That describes wide-FM as for high-fidelity broadcasting (FM Stereo band), in which case the "narrow band" mode they refer to is actually the recently-obsoleted wide-band standard (5KHz deviation). The new narrow-band standard is 2.5KHz which it looks like that radio does not support (that excerpt reads the same as from my FT-50R, which also does not support the new narrow standard).

    A wide band radio should still be able to receive a narrow signal, however the audio level will be lower, and the signal-to-noise ratio won't be quite as good, but for reasonably strong signals it should still receive them.
    I would say your issue most likely is a combination of the antenna not being resonant at the freq you're trying to receive, together with the radio's RX sensitivity not being as good out of the band it was designed for.
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  8. #8
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    So were you ever able to sort this out and get it working?

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