Mobile Base Station?

[Watergate]

So here's the situation. I spend 5 days a week living on the road. I do my best to get out on the air, but my mobile antenna choices are limited due mostly to abuse received from trees and uneven roads. You wouldn't believe how fast a shaft on a Wilson Trucker will snap just from the truck swinging back and forth.

So it got me thinking, I shut down most evenings around 5 pm and get going at 4 am the next morning. Where I park is quiet RF wise, and I hear lots of traffic on SSB. I have been wondering about mounting a base antenna such as an A99 on the top of my trailer when I park. Or maybe even a 102 whip. I am concerned with the durability of a fiberglass antenna. The antenna would have to come down of course when I drive, and it would have to ride it a hose tube which is only 16 feet long. So an A99 would have to be taken apart every day and reassembled each time I use it. Not sure I want to do that. 16 feet is all I can get for storage, no more. I could lay the antenna down on to of the trailer, but then it would be subjected to cement powder being spilled all over it when I load.

Then there is the mounting issue. Here is what I'm working with.


The trailer is all aluminum, except for the suspension. It is also basically one piece of aluminum. From the frame to the top rails, every piece is welded. The only bolting together of pieces is between the frame and the suspension and the fifth wheel plate. Mounting any kind of antenna in the center if the trailer would require drilling a hole to mount it, and that is out if the question. These trailers unload under pressure. 14.5 psi doesn't seem like alot till you see an end cap come off at 10 psi and compound fracture a leg. Not pretty.

I have three possible mounting points.

First on the front of the trailer is this lip.

It is 1/8" aluminum. I could fabricate a mount that would attach with wing nuts or some sort of quick release. Something to pinch the lip.

Or I can do the same with this lip.
I MIGHT be able to talk my company into letting me drill a hole there, but most likely not.

Here is a top view of these two lips.


The other option I have is clamping an antenna to the back of the trailer on the access ladder, but that would require alot of coax.

So I guess my questions here are am I up in the night with this idea? Is it worth the effort? Will I gain enough signal to make it worth setting up and taking down each time I use it? If it is worth it to try, would I be better off running an A99 or would it be more practical to put a 102" whip up there. And would any of my mounting options provide for efficient antenna operations, and if so what would be the best choice.

Sorry for the book, but I've been reading alot about RF grounding, and I have learned that I need to read alot more about RF grounding.

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[cordova lucky 13]

Hello Watergate : I,ve got a couple cheap quick-fix ideas you might try for your set-up ? Both i,ve used in different situations with some success & might work for you . The first item is a metal clamp set used to clamp truck caps onto pick-up trucks you will find them at RV centers that sell truck caps . I,am sure this would allow you to clamp antenna brackett to the lip on top of your tank rail , without drilling holes. Used with a swivell brackett you could possibley lay the antenna down across the length of the tank ? Secound item i,ve used is the mount & arm used to mount the small sattellite dishes ? Around here they can be found at waste sites , scrap yards , yard sales etc; for next to nothing . I,ve used this dish arm to mount A-99,s in several set-ups & would think you could use it clamped to the top rail ?? Not sure if installing the A-99 would be worth the trouble of assembley each nite butt the 102" steel whip might just work fine? Good Luck ! will stop back by for your progress update & pics ? Bob.Cordova Lucky 13 .

 

[Watergate]

The reason I ask about the A99 in particular, is I can get one for the low price of climbing on a roof and taking it down. A former neighbor of mine mounted one to a vent pipe on his roof and started talking to me over the TV.

I have considered laying it down on top of the trailer, but I do worry about cement powder turning to concrete on it, and it jumping up and down at 75 mph.

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[cordova lucky 13]

Hi Watergate ; what about a homebrew diapole between the trailers elevated just above the tanks ? I,ve used them portable before for ssb skip with some decent results , horisontal it would radiate off the sides ? Just not sure how much the tanks would effect match or pattern , but are cheap to build. later Bob.A.

 

[W5LZ]

How much trouble is keeping that concrete dust off of your truck? If it's not a huge problem, then I don't think I'd worry about the antenna.
Is there any way/place to mount the antenna where you park the truck instead of -on- the truck?
Just for grins, you might try using that 102" whip mounted to one of the places you listed. I would think that it would certainly work, no idea how to guess on the differences in performance.
Any trees/poles/whatever where you park? How about hanging an antenna from one of them? If they are tall enough, hang the thing vertically, and carry the feed line with you?
Good luck.
- 'Doc

 

[hookedon6]

The reason I ask about the A99 in particular, is I can get one for the low price of climbing on a roof and taking it down. A former neighbor of mine mounted one to a vent pipe on his roof and started talking to me over the TV.

I have considered laying it down on top of the trailer, but I do worry about cement powder turning to concrete on it, and it jumping up and down at 75 mph.

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couple of thoughts,.... that rig is SOOOOOOOOO clean, you must pressure wash it daily, I wouldn't be worried about some dust on a FREE(!!!!!) antenna

second,.... do you park in the same place nitely? why not mount the 99 on a pole near where you park and just run the coax to the rig?

 

[Watergate]

Hi Watergate ; what about a homebrew diapole between the trailers elevated just above the tanks ? I,ve used them portable before for ssb skip with some decent results , horisontal it would radiate off the sides ? Just not sure how much the tanks would effect match or pattern , but are cheap to build. later Bob.A.

I have definitely been considering the homebrew route Bob. A couple of ideas have floated around in my head for that.
Funny thing about radio, before I started getting interested in radio as a hobby, homebrewing was making beer. And my user name, which I have used for 15 years, had no other meaning to me than a reference to my name.

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[Needle Bender]

I'll have to leave the location & style of mounting system up to you, (Maybe a mounting bar to go across the tops of the diagonal vertical side rails with a monster size Vice Grip on each end?) but if you needed to shorten the A99 you could get a 4' Firestik (or equivalent) and simply unwrap the wire until it duplicates the performance & tuning of the stock top 6' whip.

You'll also find a more affordable price for the very rugged Hustler quick release at many Truck-stops, (I usually see them for $12-$15) which you could use to speed up removal of the top if you would still want or need to, once shortened to ~16'.

I hope to hear you hammerin' in on the band from your "Mobile Base Station", but you might have to fight 'Pound Puppy' for that description which he's been using for years on Ch.17 AM! :laugh:

 

[Watergate]

How much trouble is keeping that concrete dust off of your truck? If it's not a huge problem, then I don't think I'd worry about the antenna.
Is there any way/place to mount the antenna where you park the truck instead of -on- the truck?
Just for grins, you might try using that 102" whip mounted to one of the places you listed. I would think that it would certainly work, no idea how to guess on the differences in performance.
Any trees/poles/whatever where you park? How about hanging an antenna from one of them? If they are tall enough, hang the thing vertically, and carry the feed line with you?
Good luck.
- 'Doc

The dust is actually a big problem. The top of the trailer has alot of cement, and barite that has collected over the years. Most places i load have a way to clean it off after they load me but some are very picky about me not getting on top of my trailer on their property. Then the powder sticks, gets damp, before you know it it's staying put. The thing about it is, it is a very fine layer of dust, then another the next time, then another.

I have thought about claiming one spot out here as my own, but it just doesn't ever seem to work out that way. I park every night in one of many places in the high desert. Just me and the coyotes. I have looked at hanging an antenna or wire from a tree, but the only tree i could that was suitable for that out here, the state knocked over to make an access road last month.

couple of thoughts,.... that rig is SOOOOOOOOO clean, you must pressure wash it daily, I wouldn't be worried about some dust on a FREE(!!!!!) antenna

second,.... do you park in the same place nitely? why not mount the 99 on a pole near where you park and just run the coax to the rig?

The picture was snapped right after a wash job, believe me, it's not always clean. This job is dusty and a real mess when it rains.

As far as putting the A99 on a pole, there is a few cell towers and other communication towers out here I have had my eye on for a while. Ha ha.

It would be nice, but impractical since I am not in the same spot each night, just the same open nothingness each night.

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[Whiplash-265]

what about two u-bolts hard-mounted into the front bumper...once you're parked you take two 10' lengths of fence poles, attack them together, attach an a99 (possibly with a gpk) or 102", raise it and drop it into the ubolts? 1, ur not screwing with something the company might get pissed over (much) and 2, you're getting some decent height, and lastly, once you take the top section off the a99 it all fits nicely into a tube

 

[Watergate]

What I'm leaning towards now I think is building a clamp mount for the flat plate of aluminum. That plate is a safety cable tie off and is 1/2 inch thick. The mount would have a tube that I could drop a pole into.

I'm thinking of building a dipole with 108" steel whips. Once they are tuned the first time I should be able to unbolt them from the mount and reattach them without loosing my match shouldn't I?

Dipole with the steel whips, light weight tubing to put it up in the air, and it should all break down and set back up quick.

I don't need to worry about wind load since I am not going to be on top of a 13 foot tall trailer in the wind.

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[Needle Bender]

What I'm leaning towards now I think is building a clamp mount for the flat plate of aluminum. That plate is a safety cable tie off and is 1/2 inch thick. The mount would have a tube that I could drop a pole into.

I'm thinking of building a dipole with 108" steel whips. Once they are tuned the first time I should be able to unbolt them from the mount and reattach them without loosing my match shouldn't I?

Dipole with the steel whips, light weight tubing to put it up in the air, and it should all break down and set back up quick.

I don't need to worry about wind load since I am not going to be on top of a 13 foot tall trailer in the wind.

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That's a good antenna design. Excellent idea for a camping antenna using the hub from an A99/Imax GP kit and a trucker mirror mount, atop a 10' pole, which the whips could slide inside for transporting.

Since we posted only 3 minutes apart, did you miss my post above about the quick releases?
You wouldn't need to "Unbolt" anything, just a quick push & turn for each one and it's together.
And don't worry about power handling, they are BEEFY!

 

[Watergate]

That's a good antenna design. Excellent idea for a camping antenna using the hub from an A99/Imax GP kit and a trucker mirror mount, atop a 10' pole, which the whips could slide inside for transporting.

Since we posted only 3 minutes apart, did you miss my post above about the quick releases?
You wouldn't need to "Unbolt" anything, just a quick push & turn for each one and it's together.
And don't worry about power handling, they are BEEFY!

I did see your post, and will look at the quick release systems available. I can leave a mount of some kind on the trailer and not worry about it.

I'm looking to get some height out if this so I want it to be up on top if the trailer.

As far as power, I'm running a Rogerbird tuned 2510. So an amp is not in my future. He does have another of my 2510s right now, maybe I'll have him put a variable power mod in it for an amp down the road.

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[Watergate]

I should have used a different thread title. I keep picturing a Cobra 2000 on my passenger seat.

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[Watergate]

Ok Needle, I thought you were referring to a quick release to mount the whole thing, mast and all. I looked at your post again and saw you had included a link. That hustler release would be mounted at the base of the whips themselves correct? If that's the case, then with the additional length they add, I would have to trim the 108s down or use 102s wouldn't I?

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