Results 1 to 9 of 9

Thread: Why would a handheld receive better than mobile or base station?

  1. #1

    Join Date
    Nov 2019
    Location
    Massachusetts
    Posts
    1

    Default Why would a handheld receive better than mobile or base station?

    This is about a VHF system used by a volunteer fire department.

    By day I'm a computer guy, so apologies in advance if I get any of the lingo wrong.

    Our station is in an island community, and about 9 miles away from county dispatch. We are not the town's main station. There is not a whole lot of topography, and sometimes the radios work just fine. Sometimes they don't.

    Each Sunday, dispatch conducts a radio check of all police, fire, and EMS units. This past Sunday, only the handheld received anything at all during the radio check.

    We have a base station with an antenna on the roof, a mobile in the fire truck which was parked outside the building at the time, a mobile in the utility truck which was off at the time, and that handheld.

    Today, there was an alarm call. The utility truck was no more than 1/4 mile down the road when the responder radioed into dispatch, successfully. The base station picked him up, but not dispatch.

    As I said I'm not a radio expert, but I was pretty stunned that the mobile worked better than the base.

    Getting any paid help would be unlikely. I'm all we've got. What should I be looking for?

    Thanks in advance.

  2. #2
    Super Moderator 5B4AJB's Avatar
    Join Date
    Mar 2008
    Location
    Meneou, Cyprus
    Posts
    2,286

    Default

    Most likely water in the coaxial cable, it's not repairable. Change the coax and make sure the new one is properly sealed with self-amalgamating tape at the antenna end...

  3. #3

    Default

    Also, check the squelches on all three radios. They should be set so that even a weak signal opens the receiver.

    Ben

  4. #4

    Join Date
    Nov 2017
    Location
    With my wife
    Posts
    206

    Default

    Is there a CTCSSish issue here? Maybe someone monkeyed with a programming preset on accident.

    I would be getting all over that problem if it were me & my station.

  5. #5

    Default also check...

    Also probably good idea to check the base station and mobile radios grounding. Once you check the grounding cord look into the grounding plane the antenna uses. Alot of mobile (car) radios use a magnetic mount antenna making a grounding plane over the metal in the car (this can improve reception). Alot of base station antennas do the same thing with wires coming off the bottom of antenna (not all antennas have a grounding plane). Hand held radios often have less grounding and power issues.
    Oh and assuming you have not already tried getting the swr reading off the antennas that aren't working well. A swr meter will be needed to do so. But a high swr could be a bad connection, bad radio setting etc.

  6. #6
    gnuuser's Avatar
    Join Date
    Apr 2020
    Location
    NW Pa,USA
    Posts
    47

    Default

    water in the coax cable is a possibility.
    with a base station the coax and connectors are exposed to inclement weather all the time (including wind) while it may not seem like much wind flexing coax can weaken or break a seal on whatever sealing compound you use.
    Its highly important to secure the cable to a supporting structure or run it through pvc pipe( conduit) as close to the antenna or balun as possible( and seal the end with silicone)
    that's how we ran ours up the tower and have had no problems with it

  7. #7

    Default

    Well Sir, I am not going to insult you by trying to put u down, so here is what I will say and I will hope that I do not offend anyone.

    I don't know what country you are in and I don't know your laws. The internet is global.

    In the United States this radio service is loosly called Land Mobile Radio Service. To work in LMRS you pretty much have to have a license. At one time it was called Radio Telephone or something to that effect.

    To work on radios you have to have both a working knowledge of how radio works and some tools and equipment.
    At the most basic level you should have a working 50 ohm dummy load and a SWR meter..

    Each company uses their own antenna connector - depending upon the frequency, so adapters for each type of radio and coaxial cable is a must. Along with that a working radio technician needs to have a service monitor, so they can check inputs and outputs of the radio equipment. They also need a working antenna analyzer. The SWR meter basically tells the operator what the feed line is doing, but can't really tell the operator what the antenna is doing. Its pretty hard to put the SWR meter up at the feed point of the antenna.

    Diagnosing radio problems over the internet is pretty much futile, my crystal ball is broken and I can't see that far into the future. The main point here that everyone missed is a list of equipment, radio make / model / even serial number is important with this type of equipment. The coaxial cable should have a make / model printed on the jacket, even just a picture of the base station antenna would help, documentation would be even better.

    A picture of the location, proximity to trees, power lines, anything that could block the signals. Ive seen locations where the trees grew, radio worked well in the winter, when the leaves came on the trees, reception dropped..

    LMRS uses lots of towers, very high power radios, very high power repeaters, so it isn't like you are trying to receive a signal from 50 miles away. Even a simple pager receives the fire call..

    Find a listed two way radio shop, if you don't know of one, call county control, ask them who their two way radio technician is, Im sure they have one. its time to call a pro.

  8. #8

    Default

    R2D2, a quick look at his profile suggests he is in Massachusetts, USA. And being that state is one of the hardest hit by this virus (therefore assuming money is tight) and this is a public service concern, I wouldnt be so quick to tell him how bad his radio situation is. Furthermore, here in minnesota, similar climate, we are just getting buds on our trees and leaves should not be a factor.

    The first thing I would do is reach out to your LOCAL ham radio club, I guarantee, if they know this is public service issue, they will line up with their radio gadgets ready to help free of charge.

  9. #9

    Default

    Any hams in Mass. willing to don a mask and go help these firefighters??? Blast a TDR pulse down some cables and take a few SWR measurements and give some useful advice? If I wasn't so far away, I'd love to visit an island and play with radios! Heck, one could even make a field day out of it. Come on, hams, this is what its all about ~ don't let this guy down.

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •