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Author Topic: travel trailor antenna considerations  (Read 774 times)
WB6LNH
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Posts: 67




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« on: April 19, 2008, 02:16:10 AM »

I have a 29 ft Rockwood, Modest trailor that i spend quite a bit of time in traveling to Hi Power rifle competitions.  Icom 706MK II G and 20 meter hamstick in truck and hy gain colinear gain vhf also.

Have been toying with the idea of a semi perm mt on the tongue portion of the trailor for some kind of vertical, not necessarily a single band hamstick type but a longer verticl with some kind of "U" bolt mount on the 4" box beam that makes up the trailor frame.  Do not want to dril any holes in the side of the trailor for mounts, only the barell connector for coax.  want a antenna that could be erected on site for what ever period i would be visiting and removed for transit.

way too many antennas out there to 'hunt and peck' one
suggestions please
tnx Rick/WB6LNH
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KG4RUL
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« Reply #1 on: April 19, 2008, 04:52:33 AM »

The first idea that comes to mind is either the Diamond BB-7V or the Comet CHA-250B.  These are both radial-less verticals which easily telescope down to a short length for transport.

Ths next rung up the ladder is a screwdriver either manual or remote, power tuned.  

A few manual tuned possibilities are the MFJ-1664 and MFJ-1668 along with the Super Antenna MP-1 portable.

Remote, power tuned possibilities are Lil Tarheel II along with other Tarheel models.  Hi-Q antennas, and High Sierra also come to mind.

Then there is a whip with a wide range auto-tuner such as the SGC line.

I am sure there are MANY other possibilities that I have not touched on.

Dennis Raymond Zabawa - KG4RUL
ARRL SC Section, Public Information Coordinator
Berkeley County SC ARES/RACES, Information Officer
SC Army MARS - AAR4GC/T
Trident Amateur Radio Club(TARC), Charleston, SC
Community Emergency Response Team, Charleston, SC - Team C9B - Instructor
W4VEC Volunteer Examiner
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K0BG
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« Reply #2 on: April 19, 2008, 04:52:54 AM »

That depends on how complicated you want the assembly to be. You could use a 4, 5 or 6 BTV. You have to replace the clamps with worm gear type hose clamps.

You could use one of the fiberglass pushup masts with a wire in the middle with an AH-4 at the base.

Or, you could even replace the Hamstick with a HiQ or High Sierra and increase your signal by a good 10 dB.

In other words, there are lots of options. Just remember, the trailer isn't going to be the best ground plane in the world (neither is the truck for that matter). Length matters, and a 30 foot vertical works very well, even if it's matched with an AH-4.

Alan, KØBG
www.k0bg.com
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K0BG
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« Reply #3 on: April 19, 2008, 04:54:43 AM »

Dennis, both of the antennas you mentioned are nothing more than a 50 ohm load with an element attached to the center conductor. In actual signal strength, he'd be better off with Hamsticks.

Alan, KØBG
www.k0bg.com
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KG4RUL
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« Reply #4 on: April 19, 2008, 11:02:48 AM »

Well Alan, I am taking your opinion with a grain of salt.  In fact, I am ordering a BB-7V with my income tax refund.  I'll let you know how it works.
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K0BG
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« Reply #5 on: April 19, 2008, 02:50:37 PM »

Dennis, you don't have to take my word for it. Read the review in QST.

If you buy one, you'll be throwing your money away, but what the hey, it's either that, or Bush will spend it for you!

Alan, KØBG
www.k0bg.com
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K7AAT
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Posts: 413




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« Reply #6 on: April 19, 2008, 09:23:37 PM »


  My choice would be ( and has already been quite successfully ) to simply buy telescopic aluminum tubing and make yourself a collapsing vertical antenna at least 20' tall and get yourself a little SGC tuner to feed it at the base.   Mount a piece of PVC to your square bumper that the bottom section of the aluminum tubing will fit into and use that as the support.  I put a machine screw into the bottom of my mast, with nut on the outside, and another wing nut on top of that nut, and simply connect my tuner to that connection.  A large braided copper connects the ground side of the tuner to the trailer chassis and should provide a good counterpoise for such a vertical on your 29' trailer.

   A Tuner such as the SGC-237 does not require any control lines,  only the RF on the coax cable and 12VDC.  You can tap off a rear light for the 12VDC. That keeps things pretty simple in that department.

   Telescopic aluminum tubing is readily available from Tower Electronics.  I just hacksawed slits in the ends and use hose clamps to hold each element in place.

    I am amazed how well mine works compared to any mobile antenna.... of course one can't go mobile with a 23' vertical but then again, I only operate when we're stopped.

    Good luck.

  Ed   K7AAT


   Good luck.
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WW5AA
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« Reply #7 on: April 21, 2008, 09:31:44 AM »

Diamond BB-7V, Comet CHA-250B, you might be able to work anyone you hear. (:-)

73 de Lindy
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KG4RUL
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« Reply #8 on: April 21, 2008, 01:54:20 PM »

Alan,

R.E the CHA-250B and BB-7V

From the QST Short Takes, 26 FEB 2006:

I toggled between the CHA-250B and a Fluidmotion SteppIR vertical antenna with a conventional radial system.

Now that is HARDLY a fair comparison.  We are talking about an antenna that can be optimized for a particular frequency and is working against a radial system and comparing it to the CHA-250B.

It turns out this antenna is NOT just a resistor as some have posited http://www.vk5zdb.com/cha250bxii.pdf.

Monitoring Times in their MAR 2006 issue compared it to a Gap Titan.  http://www.monitoringtimes.com/html/mtrevumar06.pdf

The eHAM review of the CHA-250 was hardly scientific and in fact had some satisfied reviewers.

==================


As far as the BB-7V, there never was any review in QST.

Again as with the CHA-250, the eHAM review of the BB-7V was hardly scientific and in fact had some satisfied reviewers.

There has NEVER been a test of either these antenna on a testing range that I am aware of.  

My goal is to place the BB-7V near to my Force 12 Flagpole and make an A/B comparison.  I will report back on the results.
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KC3EF
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« Reply #9 on: April 21, 2008, 07:00:11 PM »

Rick,

I am installing a Shakespear marine HF SSB antenna with an ICOM AH-4 tuner on my class A RV.  It will be folded down under way and deployed when parked. Its hard to get a 23' antenna through an underpass, hi hi.
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