Experimental Question?

[fyreater21]

I own a MFJ-1796, which I converted to a horizontal dipole, and stuck it up in the attic. (Live in an HOA) I also have a FTD-20 and a OCFD in the attic. My Question is this, since the 1796 is a dipole, and I tuned it for the center of the HF bands, (I eliminated the 2 meter portion as I have a 5 element yagi for that in the attic on a rotator), would it be worth while to attach a 4:1 300 watt Guanella balun to feed it in place of the coax wound balun. I mean it is going from a balanced dipole to unbalanced coax or is it just a futile effort on my part. I also have a LDG auto tuner. I have a ft-857d as my base radio output is 100 watts max.
My question for asking is this, because of the narrow band width of the antenna, would the balun and tuner allow me to use more bandwidth with the antenna. Or am I:bdh:

 

[wavrider]

Hello and welcome to the Forum.

How long is the 1/2wl dipole? this will determine operating frequencies.

If the antenna is to be used as an all band doublet, then using low loss ladderline to feed it would be the best bet.

The coax is designed for a 50 ohm impedance, when trying to use a dipole as a multi band dipole there will be high VSWR on the feedline (coax) this will greatly reduce efficiency on frequency that the dipole is not resonant.

If you can use a short run of coax (10' or less) to the attic then connect the current balun 4:1 or 1:1 does not really matter, use what you have.

The small run of coax will not greatly reduce the efficiency of the antenna.
the ladderline will also radiate somewhat depending on frequency of use.

Hope this helps.

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

 

[RatsoW8]

The choke (ugly) balun should be fine.

 

[BJ radionut]

My Question: How did you modify the MFJ vertical antenna to "a Horz Dipole"? And it's working on the center freq's of what bands?...
Not saying it's not a good idea just curious....
The OCFD...how is that set-up? Bands covered/length?
You must have a large attic space...
Give us some more info...
All the Best
BJ

 

[W5LZ]

I'll echo that question; how did you convert that antenna to a 'dipole'? Used two of them??
- 'Doc

 

[fyreater21]

An answer to your questions.

Ok, to answer the question of converting the vertical to a dipole, it is pretty easy. The antenna is center fed anyway, so by taking the bottom "L" portion and inserting it into the bottom end of the mast, you just converted it to a dipole. The antenna was then laid across a couple of wooden supports I extended off of the trusses. The basic idea came from another ham who posted it on the internet.
I built my own remote antenna switch, works 7 to 150Mhz, no problems yet. I have room for 5 antennas on this box. I use a 5 element yagi I made by converting a 6 element analog TV antenna and a Elk 440 yagi. Both are on a PVC mast mounted to a rotor mounted to a plywood plate on the ceiling joists.
The shack is a work in progress and always will be.
I have 40, 20, 15, 10 & 6 meter bands on the MFJ-1796, which I tuned for the middle of their respective SSB portions of the band.The narrow bandwidth of this antenna had me wondering if in fact a guanella balun instead of the "ugly" balun wouldn't be better for performance. I have already made a replacement for that, because the one from MFJ had some issues.
The OCFD is cut to 66' total length and I am using a 4:1 balun there.
My attic is 50' in total length about 12' high and a usable width of 22', but have meandered the antenna through the attic on plastic electric fence standoffs, like a snake and have only about 4' on each end hanging down vertically. It works well, and tunes up nicely on 40, 20, and 10.
I have no visible metal, other than the truss plates in my attic, all stacks are PVC and roof shingles are a composite material with no metal.
I love to experiment and build. I will build anything, as long as it makes sense or is useful.