How to roof mount a vertical antenna?

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Martin G. (Marty) Blaise:
I am considering purchasing a Hustler 4BTV antenna. I have heard the best way to use this antenna if possible is to roof mount it with 4 radials wires. I have never installed a vertical antenna, but have wanted to try one. My question is what is involved in roof mounting an antenna such as this? How many holes have to be drilled into the roof? How high is the antenna feed point above the house? Can one person raise the antenna? Are guy wires needed? I'm basically looking for a tutorial on how to do roof top mounting of a vertical hf antenna, particular the 4B or 5BTV. Thanks.

KQ6Q:
First, you do NOT want to make your roof leaky !
What part of the country do you live in, what kind of roof - flat, peaked, sharply peaked ? Composition shingles, tile, tar and gravel, metal ?  Community restrictions ? Likelyhood of lightning ? Trees in the area ?
A vertical on the roof may be a good idea, or it may not. Have you contacted any radio clubs in your area, for a local elmer to have a look at your situation ?

What are you using for an HF antenna in the meantime, and how well is it working ?

Fred Wagner, KQ6Q

Steve Jackson:
Looks like you are still trying to recover from the hurricane.  My hat is off to you, and hang in there, you'll be back up to speed in no time!

To put up a roof vertical for HF (which I've done... but which may be something different that what you wish to do)  ... You'd typically need a roof mount of some type, and a short section of mast.  The antenna would mount to the mast, as would the radials.  Depending on many variables, everything from pitch of the roof to wind expected to the manner you secure the mount, guying is a complex decision.  Whether you could install this yourself is a pretty subjective thing.  I would not even attempt doing it by myself unless the roof was big, flat, and not too high.  Your dexterity, strength, and so forth are major factors, of course.  To what degree do you want to bullet-proof this installation??  Can you get to the underside of the rafters in the attic?  Is there a web site where you have pictures of any of this?

Lastly, are you certain you'd be happy with so few radials?  I should think I'd want at least three per band.

Sadly, the internet is really a poor replacement for providing better-done-in-person types of assistance, and this may well be one of those cases.  You have lots of local resources, of course, so you should be good to go.

Tom Hybiske:
Actually, I think elevated mounting can be  problematic.  Radial-wise, 4 radials, elevated high enough, over decent soil is equal to the much ballyhoo'd 120 buried radials of a ground mounted vertical.  The problem is you can't do it with just 4 radials....you need a set for each band of your BTV.  You need to keep them far enough apart, and you need to keep them away from other objects.  You need to sufficiently decouple the feedline, and because your radials are literally the missing half of your antenna, you need to make sure they are meticulously tuned, keeping in mind the VoP of the wire, rather than physical length.  Then it come down to what is too long or too short, the antenna or the wires.  Because it's probably right over a living space, your electronic devices, ie radios, telephones, TV, VCR's etc will be subject to high RF fields and possible RFI.  It can be a labor and time intensive procedure in order to get a roof mounted installation  right.

Answering your other questions:

One person can easily raise and lower it.  If you loosen the bottom most hose clamp, you can lift it righ off the mounting bracket.  Trust me, you will need to do this a lot in order to tune it.  Rarely, does it tune up according to the dimensions in the instructions.

The height of the feedpoint is up to you, but it is advisable that the radials slope away from the base of the antenna.

You will neeed something to fasten the mounting bracket to; a light mast, post, etc. In doing so, you will need to guy the mast with light wire. The guys will act as radials, so they need to be broken up with  small insulators.  Because the antenna is in the clear, it will be subject to high winds.  You may need to guy the radiator with a light Dacron line. 3 point guying will suffice.

Ground mounting has it's own set of problems, but if you're just starting out, I'd advise ground mounting it initially using a few dozen radials laid out on the grass, and pinned down every few feet along their length.  Perhaps after using it for a while, maybe then attempt an elevated mount.

THe Hustler is a fun antenna, works well, and is easy to assemble.  I'd not bother with the 5BTV, and the 80m resonator offers only a frustrating sliver of bandwidth.

Steve Katz:
4 radials is not sufficient, but 4 radials "per band" is.

Here's an article on roof mounting a 6BTV, which is very similar to the antenna you're considering, and it includes photographs:

http://www.eham.net/articles/4148

WB2WIK/6

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