Cant tune Antenna on cascadia

Discussion in 'CB Radio Forum' started by wa1bsb, Aug 3, 2014.

  1. Voyager1968

    Voyager1968 Road Train Member

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    I'm happy to report SWR of 1.4 across the board with a k40 top loaded 4 foot antenna mounted to a perch.
     
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  3. mike5511

    mike5511 Road Train Member

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    On a Cascadia mirror mount perch? That's pretty good, I'm very surprised! Never tried that antenna. Top loaded is the key though.
     
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  4. JChors

    JChors Medium Load Member

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    You'd think Freightliner would've addressed this issue by now, but nope.
     
  5. kor b

    kor b Light Load Member

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    HF reception is not even on their radar. IMO
     
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  6. mike5511

    mike5511 Road Train Member

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    You are right!!! Walmart complained because their automatic truck wash was tearing off the antennas on the side of the sleeper. Freightliner put them on the back of the sleeper. They are right up against the back of the cab, on the same mounts they use on the side of the sleeper, and only stick about 4 inches over the top of the cab. Every one I've checked so far pegs my RS SWR meter in the red! What a joke!
     
  7. handlebar

    handlebar Heavy Load Member

    Nearly nothing you can do to a truck with a plastic cab, short of mounting your antenna(s) on the roof of your trailer (if you always haul your own) is going to help unless you're able to fit a half-wavelength long antenna (around 18 feet) on your roof and end-feed it.

    For those not blessed with jurisdictions that permit such heights, and have no overhead obstructions with which to contend, please allow me to offer a couple of modest (yet effective) ideas that work for some folks (including me, a 20 wpm Extra Class, commercial GROL licensee, 45-year commercial tech, 50-year CBer, and 53-year ham).

    http://www.thetruckersreport.com/tr...n-fiberglass-cabs.html?highlight=DIY+solution

    or Post #4 in this link:

    http://www.thetruckersreport.com/tr...igh-swr-whats-next.html?highlight=copper+foil

    The second link refers to an earlier post I'd made, but haven't been able to set up the search terms right to find it....

    Mea culpa.

    73
     
  8. mike5511

    mike5511 Road Train Member

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    I tried that using the stock mount on a Cascadia (the one on the side of the sleeper.) However I used the stock coax which was still tied into the AM/FM antenna on the other side. It didn't do a thing for the SWR. I know a counter poise can be very effective, but it didn't work in this case. For those of us using a perch mount on the cascadia, I intend to weld a nut out on the end of the perch and just screw the antenna into it and see what difference that makes. I just haven't done it yet.
     
  9. soremonkeybutt

    soremonkeybutt Light Load Member

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    I dont know why so many drivers go cheap and then expect performance go with a wilson trucker 2000 or 5000 never had any problems
     
  10. handlebar

    handlebar Heavy Load Member

    Mike, that nut welded to the perch oughta work like gangbusters. It sounds like it would be a lot physically neater than my kludged mirror clamp, and it'll be easy to get to if it's either in your way of you want to change the length of the counterpoise half.
    And remember to try to get on-air reports from folks far enough away to be able to let you know what's stronger/better as you test. An awful lot of folks get hung up staring at the VSWR meters and stake all their opinions on that. Remember, a half-wave dipole is around 72 ohms, and a quarterwave element over a flat "ground plane" will show around 35 ohms; either one will present a 1.5:1 VSWR, plus or minus any silliness induced by a strange coax length. I'd personally go for the greatest apparent transmitted signal strength, then make a note of the VSWR and just write it down someplace so you've got it for a reference. If it turns out to be 1.7:1 AND it's the strongest signal in the field, I'd be really happy.
    FWIW, I've just (in the past hour) talked to Spain, Canary Islands, St. Lucia, Venezuela, Namibia, and Slovenia, all with wire antennas that indicated VSWRs of from 3:1 to 5.4:1, and only 40 watts to the antenna. I just backed down the power to take it easy on the coax and transmitter.

    Toodles & good DX
    73
     
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  11. mike5511

    mike5511 Road Train Member

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    I guess you haven't read some of my posts about the Cascadia. I've used a Wilson 2000 with every conceivable shaft length including a custom length. The Wilson works good as far as a low SWR on the back of the Cab. But, I couldn't get a decent SWR on a mirror perch mount with one unless I leaned it forward to get it away from the A-pillar. The 7ft Skipshooter I'm running now performs better than anything I've tried.....including the Monkey Made. The A-Pillar has a significant influence on SWR on the Cascadia. You have to get the load coil away from it to obtain a decent SWR reading. The only useful way to do this is get the load coil above it. It will also work if you lean the antenna forward away from it. However you will be killing your signal strength by doing this. (I don't care how many "Bull Haulers" tell you it doesn't hurt their signal to go horizontal.) The mirror has almost no influence on the SWR reading. I can touch the antenna to the mirror and it won't change the SWR reading. But when I start moving the antenna toward the cab, it rises rapidly.

    There is a difference between "cheap" and "inexpensive". A Francis 5.5 ft. is relatively inexpensive. However, it will perform very well in most cases. I have never been able to tell the difference between one and a Wilson 2000 or 5000 as far as performance goes. The freight haulers ran the Francis 5.5 ftd for years back in the day and you could always hear them coming for miles.
     
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