Building a mobile mast for 2M use.

[BigJimCruising]

Having done comm's for races in remote areas before I've found that simply adding 30 to 50 feet of height to an antenna doesn't really make a whole lot of difference unless it's supporting a good high gain beam antenna. Another option to consider which works much better if there are some tall hills nearby is setting up a cross band repeater. You can station this quite some distance from where you are operating (observe rules for cross banding) and improve your range considerably over a mast design. If you can put one of your vehicles with radio already in it then it's easy. Or you can build a portable station with a battery and generator and just have someone go up from time to time to add gas. Done right you can work your check point from nothing more then a handheld radio with a couple spare batteries. Or something along these lines, you get the idea of where I'm going with this. I've done these systems and they work out very well the higher the hills around you are. Food for thought! Jim.

 

[crawler#976]

A crossband repeater would be nice, but a my radio gear is not capable of that. A beam might be an option, but we also contact other check points and recovery trucks. We usually have multiple radios tho, so I may look into a beam for the Parker.

Sent via gigawatt laser...

 

[DaveInDenver]

True, putting your V/UHF antenna on a mast is a marginal performance gain but does get it above people and thus reduces chances of having someone touch it while transmitting.

 

[DaveInDenver]

I suspect getting it just above people, cars, fences and shrubs would make a big difference in attenuation. At my QTH just moving the antenna 6 feet higher from the side of the house to the roof made a huge difference by being above all the neighbor's roofs. Doesn't change line of sight limitations much, though.

 

[crawler#976]

6 poles for a 24' mast, three paracord guys, three 12" stakes, and a 24" concrete stake to anchor the base, to which I added a fourth petal. Worked like a charm! Got good reports from Flagstaff - 48 miles away. It takes a few minutes to assemble, but once in place, I think it will help my comms out quite a bit.

 

[crawler#976]

Found a heavy wall cardboard tube to stow the folded antenna and cable, and without the pieces that Lance is getting for a discount (since I'm keeping the bag), it all fits into the original bag. For the few times a year it will get used, I'm pleased with the result and cost.

 

[crawler#976]

When I assembled the antenna, instead of installing the radial per the instruction manual, I bought new hardware to attach them to the outside of the case. With them setup that way, they fold up along the sides of the case, and that makes it very compact for transport, yet very easy to deploy when needed.

 

[briansocal]

Good job on that mast. Looks like you could probably equip it to handle a wire antenna of some sort as well. That'll come in handy.

 

[crawler#976]

Used the mast this last weekend at the Prescott Rally. Worked great!

I had the chance to do some testing, specifically trying to reach the Smith Peak Repeater that links to San Diego. The distance from my location was 89.4 miles, and I have several mountain ranges in between the two points. Elevation wise, I was at 4450', going over a range at 7000', and Smith Peak is at 5100'. At 75W with the Larsen NMO 150B 5/8 wave antenna on the truck, I could break squelch on the repeater, but was unable to get out. The mast had no problem getting thru with a clean signal at 25W.

Mark

 

[1911]

Good deal, thanks for reporting back on your success.

 

[crazy]

I haven't read the whole thread but I thought about a collapsible/telescoping flag pole for a mast. That's what I had planned for. Not sure how strong the cheaper ones are.

 

[Prybry]

4 section paint pole from Lowes works too...

I use a three section aluminum painters pole I picked up at Lowes for less than $25
I have a Arrow 2M/440 antenna clamped at the top and sometimes run a PAR 10/20/40 HF end fed antenna at an angle to the top as well.
In the photo you see the antenna deployed at the John Beargrease sled dog race about 100 miles north of Duluth
The pole is attached to the back of the camper and puts the antenna about 25 ft in the air...



Prybry

 

[DaveInDenver]

That looks great Prybry!