Condo HOA issues-multi band diapole attached to balun, fed by only coax

I've been silent for 15 years, studying to take General exam, forgot most of what I learned then. Pls make reply simple to understand.

I have attached 45' of 1" PVC from first floor bedroom to roof top (building is 4 story all concrete with flat roof and 3' wall around top) PVC will hide RG-8 coax running from Tuner to Hy-gain BN-4000B balun mounted on top of a 6 foot - 2" aluminum pipe on inside of wall on roof. Building, PVC and pipe was just painted so looks like supposed to be there. Will attach two - 60' braided wires directly to balun and run each end across roof top to two separate peaks approx. 7' above the concrete roof creating a "V" of about 90 degrees almost parallel with the roof. Have driven 8' copper rod outside of bedroom window and hidden with a bush.

Cannot mount anything directly to roof floor, commercial antennas are out because they would be seen. This is only way I can get anything "in the air" without it being seen.

Question is : can I run coax from tuner, direct to balun and make "V" wire antenna work. I really don't see any other way since I can't use ladder line.

 

Wow! How did you manage to attach 45' of 1 inch pipe to the building without anyone seeing you?
Any chance you could run some ladder line up the pipe instead of coax?

 

Why braided wire?

The only way to tell if this antenna will work is to build it and implement it. If the roof has some sort of RF conductive material in it, it may not work well.

I would suggest the following amendment to your plan - run six regular wires, two 66 ft. long (you can use loading to make them a little shorter or bend the ends around to fit available space), two about 33 ft. long, and two about 16 1/2 feet long, making a parallel-fed inverted vee on its side. This will get you 80, 40 and 20m (the best bands right now), can all be fed by one feedline, and once pruned, won't require a tuner on significant portions of each band (a tuner is still desirable for band-edge excursions). If the wires are run in the same plane vertically then it should be possible to keep the included angle for all of them at 90 degrees. Just separate the ends by a foot or two.

This is the part I would think about next. You need to know if it's significantly less than 90 degrees; if so, your antenna, as planned, has a big strike against it, since dipoles with the included angle smaller than that can suffer significant losses from cancellation. The first dipole I ever built, as a Novice, had an included angle of about seventy-five degrees, and was worthless.

To answer your implied original question, can you feed a multi-band doublet with coax instead of balanced line and not be disappointed in the result, the answer is two old saws: "anything 'works,'" but "most knowledgeable and experienced hams don't do that."

 

I am on the Condo board and had the painters attach the PVC while they were painting using a sky lift. In the PVC will also be run RG-8X for the Ed Fong dual band. I could try to replace the RG-8 and try to fold the ladder line around the
RG-8X. If so, where do I attach the balun --- inside my bedroom and run 3'-4' of RG-8 to the tuner???

Building a "fan diapole" will surely be spotted by the adjacent building. I'll be lucky if I can get buy with just one off each side of balun. Normally only people allowed on roof are board officers, me and one other and air-cond. repairmen. I had to put the 6' pole on the roof wall to keep from cutting their heads off!

Because of where attachment points have to be, the "V" is very very close to 90 degrees. I'm really trying to do this a proper way and I really appreciate all your help-really do.

 

It's a "dipole".

If you are limited to coax feed, you want a trap dipole. The classic W3DZZ design is a good one.

 

Thank you for correcting me and for your suggestion of a trap dipole. I will read about it and see if I am able to do it.

 

I maybe reading it wrong, but, The way I read it is, he has an inverted inverted V.
The feedpoint @ 6 ft and the ends @ about 10 feet

 

The feedpoint is at top a of 6' pole anchored to the 3' wall around roof. The "V" runs across the concrete roof and ends at 7'. The angle is just shy of 90 degrees. Would it make any difference if I made the V level at 7' ?

 

Use coax not ladder line. Look at a multi band trap dipole. You will get out

 

True, BUT if you hang diapers on it to disguise it as a laundry line it then becomes a .........