Have Radio, No QSO

[KB1SYV]

Cool, I need to talk to him more tommorrow, but I would like to go to him with some sort of cursory plan. I assume the roof is pretty big, conservatively 30X40, I don't know if there is any obstructions up there though. I also don't want to get him skiddish by showing him a plan to take up the whole roof. What can I do without spending too much more and getting multiple bands??

73,

Jethro

 

[Moleculo]

Build yourself a wire antenna. The cost is minimal and they're easy to build. You probably have enough room for a 40 meter loop. Here is a calculator: Loop Antennas and Calculator

It doesn't sound you have enough room for a 40 meter dipole unless you want to build a trapped or loaded version. You could build a 20 meter or higher band dipole, though. What are you going to use for feedline: coax or ladder line?

 

[KB1SYV]

Is there any way I can get something up there that will allow operation on more bands?

 

[Moleculo]

Is there any way I can get something up there that will allow operation on more bands?

That's why I asked you what type of feedline you planned on using. If you use some type of parallel feedline (ladderline, for example), you can tune all the higher bands than your antenna is cut for with minimal loss. It will really work well. For example, if you put up a 20 meter dipole, you could use your tuner to get 17m,15m, 12m, 10m, 6m. You could do the same thing with coax, but it won't work nearly as well.

The other option if you use coax is to make multiple dipoles fed off of the one feedpoint. This is called a fan dipole. There are a lot of other types of wire antennas you can make; I'm just giving you some examples.

 

[KB1SYV]

I can buy ladderline if it will get me better result's. What could I use as posts to wrap the wire around? I'm probably going to have to do a horizontal. Do I need to wind wire more than once? What kind of gauge wire that will hold up to ice and snow. I have an ldg at897 autotuner without a balun, will I be able to direct feed the antenna to the ladder line, to the tuner? Any suggestion on how I would ground this as well?

thanks for your time and patience by the way.

73,

Jethro

 

[Moleculo]

I can buy ladderline if it will get me better result's. What could I use as posts to wrap the wire around? I'm probably going to have to do a horizontal. Do I need to wind wire more than once? What kind of gauge wire that will hold up to ice and snow. I have an ldg at897 autotuner without a balun, will I be able to direct feed the antenna to the ladder line, to the tuner? Any suggestion on how I would ground this as well?
Jethro

You can use just about anything as posts; the key is to make sure it can stand up to the weather. Even a wooden broom handle can work if you can weatherize it. You should be able to find some TV antenna style masts at a local hardware store and figure out a way to mount them on the roof somehow. You'll at least need one to support the center of the dipole and you may need one for each end. You need some insulators of some type, as well. You can make your own out of something or buy them. Here's a little picture:

You can see in this picture coax is used. If you use coax, you can run the feedline next to anything practically. If you use ladder line, you have to be a bit more careful. You certainly don't want to wrap it around masts! Most dipole calculators assume 14 gauge wire, but any size can be used. 14 gauge will probably handle whatever weather you can throw at it. It doesn't matter how many wraps you use to tie it off to itself...just enough that it is secure. On the outside of the insulators you can use guy wire, rope, whatever you have to work with.

Unless that autotuner has terminals for parallel feedline, you will need a balun if that is the type of feedline you want to use. They're not expensive for a 100 watt rig.

 

[Moleculo]

Here's a link for building a simple doublet (That's what a dipole is called with parallel feedline)

The All Band HF Doublet - 80 thru 10 Meter Ladder Line Multiband Antenna

 

[KB1SYV]

Any suggestions for suitable grounding, or is it necessary?

 

[Moleculo]

It's not necessary to make that type of antenna work. You should try to do some type of station grounding at the rig, but that can be difficult to accomplish if you're in an apartment and not on the first floor. Try it without and see what happens...