Tilt-Over Mast For Scanner and CB - A Noobs Endless String of Questions

[kingshootr]

In about a year from now, I'll be retiring and one of several things I look forward to is enjoying listening to the scanner. No broadcasting, but having a CB would be fun I think. I'm in a city now, with 2 SDR dongles and this antenna mounted about 15ft off the ground.

I'll be in a rural area of NE Arizona - Lakeside/Show Low area. My land is at the edge of the forest so there will be about 100yds/meters of pine trees between the antenna and the clear area of the surrounding towns.

My "shack" will be the corner of a metal building. I don't really want to mount the antennas on the roof (unless you tell me there is a significant upside), instead I'm leaning to a tilt over mast design. I like the ability to lower it for maintenance, the inevitable upgrades, etc. I'm also planning ahead so at 70, I won't be risking life and limb messing with it on a roof.

My other hobbies are metal working/fabricating/welding - so the construction of one is pretty well in my wheelhouse, at least by looking at all the designs I've researched so far.

So, on with the first questions...

1] I get quite intimidated reading the other threads regarding grounding/bonding and the like. Are most licensed electricians savvy with the ins and outs of working with antenna installations (the electrical safety side of things)?

2] I'm not going to go crazy with the height, 30ft is where the dart I threw landed. That will still be below the treetops. Am I doomed with this setup for the ability to listen to local municipalities and such? My property is up on a hillside so I'll have that as a bit of an advantage.

3] I want to get a better scanner antenna - discone or the like. I know it's been asked a zillion times, but if you made it this far - I'd appreciate recommendations on the latest and greatest, or the tried and true designs to consider.

Well, that's enough boring for now. Thanks in advance for any and all critiques, advice, and assistance.

 

[fxdscon]

Check this article in the Wiki:

Tilt-Over Mast - The RadioReference Wiki

wiki.radioreference.com

 

[mmckenna]

I'll be in a rural area of NE Arizona - Lakeside/Show Low area.

Nice area, I was through there a few years ago and really liked it.

My "shack" will be the corner of a metal building. I don't really want to mount the antennas on the roof (unless you tell me there is a significant upside),

The upside to mounting on a metal roof is you get a nice ground plane for the antennas.

instead I'm leaning to a tilt over mast design. I like the ability to lower it for maintenance, the inevitable upgrades, etc. I'm also planning ahead so at 70, I won't be risking life and limb messing with it on a roof.

Not risking injury is a pretty darn good reason in my book.

You can easily fabricate a ground plane for any antenna with your skills, so, yeah, go with the tilt over mast.

My other hobbies are metal working/fabricating/welding - so the construction of one is pretty well in my wheelhouse, at least by looking at all the designs I've researched so far.

So, on with the first questions...

1] I get quite intimidated reading the other threads regarding grounding/bonding and the like. Are most licensed electricians savvy with the ins and outs of working with antenna installations (the electrical safety side of things)?

A good electrician should be able to properly ground your system to meet National Electric Code, and that's what you want at minimum. For receiving/CB, that's way better than what most have.

2] I'm not going to go crazy with the height, 30ft is where the dart I threw landed. That will still be below the treetops. Am I doomed with this setup for the ability to listen to local municipalities and such? My property is up on a hillside so I'll have that as a bit of an advantage.

Without knowing exactly where you are, it's hard to say. But being on a hill side and adding 30 feet of mast is a pretty good setup. As long as there isn't a huge pile of dirt between your antenna and what you want to hear, you'll be fine. For VHF/UHF and up, line of sight is what works, so the higher your antenna is, the more you'll be able to hear.

3] I want to get a better scanner antenna - discone or the like. I know it's been asked a zillion times, but if you made it this far - I'd appreciate recommendations on the latest and greatest, or the tried and true designs to consider.

Letting us know what your budget is would help us make a better recommendation.

However, a discone is a good place to start. The real benefit to a discone is that they are really broad banded. That can be useful if you have a wide range of frequencies you want to hear.
The drawback to a discone is that they have zero gain.

That trade off is something to consider. Gain improves the signal strength of the signals you can hear. Looking at the agencies around you, it looks like everyone is pretty much VHF with a few UHF users scattered in. A purpose built dual band base antenna designed for the commercial (not ham) frequencies would have more gain than a discone does.

Since you really don't need anything other than VHF and UHF to hear your local agencies, the wide band benefit of the discone antenna may not be something you need.

Avoid the gimmick antennas. Get a good dual band vertical. Something like a Diamond X50NC2 would be a contender in that field.

And make sure you use good coaxial cable suitable for the length of the run.

 

[kingshootr]

That is the basic design I see mostly. I'm working on the numbers to see if a counter balance system will work instead of a winch.

2.5" schedule 80 is 7.5lbs/ft. 7.5 x 33ft = 250lbs or so. With a 5ft fulcrum point and a 250lb counter weight, the tip over effort should be in the 30lb-ish range.



I'm not smart enough to calculate how the mass of the pipe actually affects the balance, so these are rough estimates. I have a 250lb and a 330lb counterweight already, and building a stout pivot mechanism is within my skill set.

Just a possible way to be different.

 

[mmckenna]

Don't forget the weight of the antenna(s), coaxial cable, mounting hardware, etc. That'll add to your weight.

But I like the design. Some railroads use a similar setup for trackside installations. Removes the need to send a human up a tower, which is always risky.

 

[kingshootr]

Nice area, I was through there a few years ago and really liked it.



The upside to mounting on a metal roof is you get a nice ground plane for the antennas.



Not risking injury is a pretty darn good reason in my book.

You can easily fabricate a ground plane for any antenna with your skills, so, yeah, go with the tilt over mast.



A good electrician should be able to properly ground your system to meet National Electric Code, and that's what you want at minimum. For receiving/CB, that's way better than what most have.



Without knowing exactly where you are, it's hard to say. But being on a hill side and adding 30 feet of mast is a pretty good setup. As long as there isn't a huge pile of dirt between your antenna and what you want to hear, you'll be fine. For VHF/UHF and up, line of sight is what works, so the higher your antenna is, the more you'll be able to hear.



Letting us know what your budget is would help us make a better recommendation.

However, a discone is a good place to start. The real benefit to a discone is that they are really broad banded. That can be useful if you have a wide range of frequencies you want to hear.
The drawback to a discone is that they have zero gain.

That trade off is something to consider. Gain improves the signal strength of the signals you can hear. Looking at the agencies around you, it looks like everyone is pretty much VHF with a few UHF users scattered in. A purpose built dual band base antenna designed for the commercial (not ham) frequencies would have more gain than a discone does.

Since you really don't need anything other than VHF and UHF to hear your local agencies, the wide band benefit of the discone antenna may not be something you need.

Avoid the gimmick antennas. Get a good dual band vertical. Something like a Diamond X50NC2 would be a contender in that field.

And make sure you use good coaxial cable suitable for the length of the run.

This is fantastic - thank you for the detailed reply.

The Diamond is towards the top of my budget for an antenna so that's cool. $150 or so would be about the max. Simpler = more gooder.

With slack for the tilt over and into the building - 50ft of Coax will be what I need.

Any thoughts on how to incorporate a CB antenna into the design? Can one be offset from the other or will there be some negative effects?

It is indeed a beautiful area - can't wait to make it permanent!

 

[mmckenna]

This is fantastic - thank you for the detailed reply.

The Diamond is towards the top of my budget for an antenna so that's cool.

With slack for the tilt over and into the building - 50ft of Coax will be what I need.

Consider cost of good coaxial cable in your budget. Times Microwave LMR-400 is about the minimum I'd use for UHF at that length. LMR-600 would have less loss, but more weight/cost.

Any thoughts on how to incorporate a CB antenna into the design? Can one be offset from the other or will there be some negative effects?

You'll want some separation between them. While a stock CB is going to be around 4 watts, and less will actually make it to the antenna, you do want to keep that RF energy from getting into your scanner. That needs to be vertical and/or horizontal separation.

While it'll add to your weight, a braced cross bar on top with some suitable sized pipe sticking up about a foot on either end would give you some mounting options.

It is indeed a beautiful area - can't wait to make it permanent!

I was there in the late spring, and it was green and absolutely beautiful. Unfortunately I was heading to a work thing and couldn't hang around. I'm headed that way later on this spring and might try to spend a day out there.

Was at the south rim of the Grand Canyon in the middle of winter a few years ago. Absolutely breathtaking in the snow. I thought it was better than in the warmer months (A lot less people.).

 

[kingshootr]

Me and the missus did a lot of camping - Bryce, Zion, the Canyon - wintertime is the best. As you said, no crowds and the scenery was spectacular.

 

[kingshootr]

5/8 wave antenna for CB. Researching CB antennas, I'm gathering that a 5/8 wave is a pretty good design to shop for?

If so, they seem to be in the 18ft-21ft range in height, yes?

Are they designed to be mounted closer to the ground rather than on a mast? Would putting one on a 30ft mast help or hurt it's performance? Would I gain that much putting it on the mast?

Since I also am going to have a VFH/UHF scanner antenna, you had mentioned separation between of them is best. I would be able to have the tilt mast with VHF/UHF on one corner of the building, and the CB antenna 12ft-32ft away horizontally from it. Depending on the weight I believe the base of the CB antenna could be approx. 5ft off the ground.

Here are a couple rough drawings that better show the location, structures, etc.

 

[mmckenna]

Either location for the CB antenna will provide enough separation if you are running legal power levels.

Mounting it so the base is above the roof on a mast.

 

[kingshootr]

Avoid the gimmick antennas. Get a good dual band vertical. Something like a Diamond X50NC2 would be a contender in that field.

Would this antenna also cover GMRS Receive/Transmit duties?

Also, would it be able to pick up aviation in the low 100-150MHz range?

 

[mmckenna]

Would this antenna also cover GMRS Receive/Transmit duties?

Should work well for that.

Also, would it be able to pick up aviation in the low 100-150MHz range?

It'll pick it up aviation frequencies, but not as well as a dedicated VHF air antenna. The X50NC2 is tuned for use up above 150MHz.

 

[kingshootr]

Should work well for that.



It'll pick it up aviation frequencies, but not as well as a dedicated VHF air antenna. The X50NC2 is tuned for use up above 150MHz.

With the brief, recent CB experience, and researching GMRS, neither sound very appealing or particularly useful to casual listening in on.

I was thinking at least with GMRS, you could hear people conversing at will, just not communicate with them. It appears that is not the case. I was also thinking (I need to stop doing that...) that businesses and companies used them for internal communications like maintenance, security, or whatnot.

Anyways, I'm now leaning back to just airbands and public safety/municipalities and the odd other industries (trains and/or?)

I saw your other explanations with diplexers for two antennas to one scanner. I'm using two SDR dongles on one multi-band antenna, and nothing more than a "Y" adapter cord to tie them all together.

I believe what I'm envisioning is an airband specific antenna Navajo County Airports, and a separate antenna for the rest. Looking at the frequency database for the area - I do not see any trunked systems - they are all in the mid-150MHz range Navajo County Municipalities

Soooo.... Perhaps a scenario or three:

* Two Sirio GPA antennas, a 108-136MHz and a 135-175MHz (If so, any idea how far apart they should be to not cause problems?)
* Something like an AirNav Airband and a VHF in the 136-175MHz range Any opinions on one like that - almost all I'm finding are short little mobile ones - which is fine if some don't need a ground plane. Although in the past, I believe t may have been you, I was guided to making a ground plane for my current antenna using horizontal rods welded to the steel base that it is stuck to.
* Get a discone and call it a day...

I'd like your opinion on if it's worth it to spend for antennas, diplexers, etc - vs a single discone. Loss of efficiency with the two antenna setup vs a discones shortcomings?

 

[mmckenna]

With the brief, recent CB experience, and researching GMRS, neither sound very appealing or particularly useful to casual listening in on.

I was thinking at least with GMRS, you could hear people conversing at will, just not communicate with them. It appears that is not the case. I was also thinking (I need to stop doing that...) that businesses and companies used them for internal communications like maintenance, security, or whatnot.

Don't completely write off CB, it may be interesting at times, but in reality, it's not the 1970's and you won't hear lots of traffic. Maybe the occasional trucker or off roader, but that's about it for the useful stuff. Personally I don't want to listen to someone yelling the same thing at me for hours on end from across the country. I've got the internet if I want that….

GMRS/FRS listening can be interesting as there are a lot of people that use it. But your existing scanner will do that just fine.

Anyways, I'm now leaning back to just airbands and public safety/municipalities and the odd other industries (trains and/or?)

I saw your other explanations with diplexers for two antennas to one scanner. I'm using two SDR dongles on one multi-band antenna, and nothing more than a "Y" adapter cord to tie them all together.

I believe what I'm envisioning is an airband specific antenna Navajo County Airports, and a separate antenna for the rest. Looking at the frequency database for the area - I do not see any trunked systems - they are all in the mid-150MHz range Navajo County Municipalities

Soooo.... Perhaps a scenario or three:

* Two Sirio GPA antennas, a 108-136MHz and a 135-175MHz (If so, any idea how far apart they should be to not cause problems?)
* Something like an AirNav Airband and a VHF in the 136-175MHz range Any opinions on one like that - almost all I'm finding are short little mobile ones - which is fine if some don't need a ground plane. Although in the past, I believe t may have been you, I was guided to making a ground plane for my current antenna using horizontal rods welded to the steel base that it is stuck to.
* Get a discone and call it a day...

I'd like your opinion on if it's worth it to spend for antennas, diplexers, etc - vs a single discone. Loss of efficiency with the two antenna setup vs a discones shortcomings?

Sounds like you think VHF Air band and VHF public safety is what you want to listen to. Looking at the database for your (and adjacent) counties, that's probably a good plan. There's a bit of UHF stuff, but not sure it's worth the effort.

Looking at your scenarios, I'd choose the Sirio antennas, but I'd go with the higher gain model for the VHF public safety:

GP 3-E

5/8 λ ground plane, Omnidirectional, 135…175 MHz Tunable, Systems: 2m-HAM, VHF Marine Band, ORBCOMM M2M, AIS-162MHz, ISM-169MHz

www.sirioantenne.it

I've got one of those at work that is plugged into a ship tracker. The antenna has been up for about 10 years, and I'm impressed with it. Very suitable for hobby use and a decent price.

 

[paulears]

I suspect your engineering background is going to make construction part of your version of the radio hobby. I like your idea of doing it with counterbalance but it brings back memories of television jib arms I used to use in the 80s. When I left one job being closed down, I bought lots of my old amazingly well engineered gear, including the arm I loved. Cameras back then were heavy and big, so the things they were attached to were equally massive. The one I have has a two meter reach, with the rear section about half that. It has a flight case full of lead weights that go on the back. Fully loaded, and it doesn’t even notice today’s lighter cameras, it goes up and down and spins with little finger pressure. Perfectly balanced.
the snag is that the arm itself has to be more massive than necessary with a winch in the antenna tower design. The load on the fulcrum is double what it would be if it was a mere hinge. So the size of the tower structure has to be increased when with a winch it could have less mass. Modern tv jibs have light weight tubing and a vertical extension going up at the fulcrum when the arm is horizontal has a cantilever wire that prevents bending. On a tower, you just omit the rear portion and winch from the extension. It saves half the overall weight, reduces the amount of steel or ali, and while not as elegant as perfect balance, the damn things tend to go up, and stay up! Does double the weight also increase the concrete base requirement? It’s fun engineering but I wonder about how sensible it is. A winch and ratchet is a lot less work.

 

[kingshootr]

I had seen those home-made/diy extendable masts. I did not put two and two together how doing one like that, combined with a much more reasonably sized counterweight, would be pretty ideal.

Even if using heavier square tube, it only being 8ft tall +/- when collapsed eliminates the overhang load substantially while being stronger when extended vertically. A small electric winch and I'm off to the races.

I like it! (except for the current costs of steel... )

 

[kingshootr]

I think I have a design to stick with - against all the ideas I've been babbling about here. I was looking at scaffolding parts and pieces - this caster mount is beefy and can easily be connected to some deep concreted in imbeds. I can't find a local supplier of just the poles though.



Then I saw these, which are a dime a dozen for sale around here:

Racking cross bars. Like on the shelves at the home improvement stores.



12 feet long for $50. Stiff as heck with mounting feet already welded on. Unfortunately I'm now 4-5 months from being able to do anything. Weather, construction delays - you know. life.

 

[kingshootr]

You couldn't pay me to live in California, but dang - I keep seeing sailboat masts for sale. $50 for a 24ft aluminum one. I have to believe that could make a pretty good antenna tower that would work for me.

 

[KB4MSZ]

it's not the 1970's and you won't hear lots of traffic

No wonder sales are down

 

[murphcc1]

For an idea of what elevations are around you go to this site, drag the blue icon to where you live, you can zoom in, then move the green icon around to see local elevation changes.

RF Line of Sight - SCADACore

RF Line-of-Sight provides radio path information for mapping long distance SCADA radio communications by using antenna height and topography.

www.scadacore.com