Here's what it looks like for now...
http://i.imgur.com/CifHvnD.jpg
Hard to tell if it's working any better. I had to cut a longer mast to get the bottom antenna over the peak of the roof. The other one was 60", this one is 100".

Performance FM Antennas
 

Well agreed on all. I had an APS-13 @ 60' until a small tornado took the tower down. While it worked well, unless there were E's or TROPO, the line of sight rule dictated what I would hear. When there was TROPO or E's, my friends Winegard 6055P worked as well.

That's NLA also....

The price of performance FM antennas is certainly up there. If there were a few people who wanted one, a group buy might take the edge off the price a bit. Still....

Thanks for the reply, tho...

Are both cables from the 2 antennas the exact same length?

Is your FM reception issue mainly static, or are you still experiencing signal fade as well?

Is TV reception affected by the stacked antennas?

I know for sure one is 6 foot, I'm 99% sure the other one is 6 foot as well but I ordered another one that's quad shielded. TV reception does not seem to be affected, radio reception seems about the same, hard to say if it's improved.

A test I did to compare 1 antenna vs. 2 is tune to channel 11.1 (real channel 11). With two FM6s connected the signal strength was 72%, with one connected (the higher one), the signal strength was 92%.

Is this a good indicator on whether I should use 1 or 2? I know channel 11 is VHF-high whereas FM would be low band.

A signal from real CH-6 would make a fair test signal, it's at the bottom of the FM band.

Real CH-11 is twice the frequency of the FM band center. It's about as bad a choice as one could hope to find because at 200 MHz, the elements of the FM antenna are twice as long as they should be in order to resonate (that actually forms a type of rejection filter). Your test suggests the combined pair rejects real CH-11 better than a single antenna, possibly due to the filter network formed by the coax + combiner harness + antennas.

For the best shot at a balanced combiner harness, use cables of equal length, cut from the same roll of coax. There can be variations between vendors, so that two store bought cable the same length, but from different sources, may not match well enough.

Quad shielding is not worth paying a penny more for... The point of extra shield is to keep signal from getting into or out of coax that's not directly connected to an antenna. (As in the case of a satellite system where there is a low-noise-block converter between the actual antenna and the coax. In a satellite system the LNB shifts the raw signal from the satellite to a lower range of frequencies. The range used in the LNB to receiver connection overlaps with land based radio services. You need to keep the two from interfering with one another, hence the extra shielding.) In OTA TV & FM, you have an antenna coupled directly to the coax, extra shielding buys you nothing, The antenna is a 'huge leak' in the shielding.

Stacking Antennas
 

There are 2 critical distances to be calculated. The first, the vertical distance between antennas. Second, the length of the phasing harness (those 2 lengths of Co-Ax which would run from the feed point of each antenna to, in this case, a Co-Ax "Tee" adapter). It's not at all difficult once you know some of the deign parameters. The first, is the physical, vertical separation of the 2 antennas for a specific result from what will be an antenna array.

Just brainstorming here but I'm thinking the physical separation value might be based on the result being a compromise between gain and frequency "broadbandedness." The mfg might already have that value and you might reach out to them and ask. Or, perhaps someone here has modeled an array using those antennas using EzNEC. The second value necessary to calculate the length of the phasing harness is based on the value of the first. That is, what is fraction of a wavelength should the length of the phasing harness be to accommodate the physical spacing value used to achieve the goal of your array.

You will also need the velocity factor of the specific brand of (probably RG-6) co-ax used to make the phasing harness. That probably going to be something like .82, .85 or something like that.

Lets put it all together. I made an 800 Mhz, 4 vertical dipole stacked array. Each vertical dipole needed to be spaced 57" apart to achieve the design goal which was flattening the pattern toward the horizon. I used 3/4 wavelength phasing sections. To determine the electrical length of those cables, I first divided 2952 by the center frequency of the antenna in mhz or, 2952/855 then multiplied that result by the velocity factor of the cable, in my case, .85 which yields the electrical length of my 1/4 wavelength phasing line. However, I needed 3/4 wavelength lines so, I then then multiplied THAT result by 3. THAT yielded the electrical length of my phasing line. So, the formula looks something like this:

2952/855= P (P* .85) = L1 (L1 * 3) = L3

Where P= Physical cable length
L1= Electrical 1/4 wave cable length
L3= Electrical 3/4 wave cable length (desired length)

So, for 98 mHz, 2952/ 98= 30.122"

30.122 * .85= 25.603" or, right at 25 5/8" for each of the 2 harnesses.

Multiply that times 3 and you get a cut length for each leg of your phasing harness of 76 7/8". Remember that an FM Tee is about 3/4 inches long so SUBTRACT HALF that value from EACH of your 2 phasing harnesses.

So, that's what the formula basically looks like. What I am lacking to make it completely accurate to your situation is the mfg's or modeling result to provide recommended spacing between your antennas.

Th example above should not be regarded as a "build to" example in your situation but rather, an example of how do perform the calculations to determine the phasing harness length once you have:

1- The recommended physical vertical antenna spacing in wavelengths for a design frequency. :confused:

2- The velocity factor of the cable you will be using to construct the phasing harnesses. :confused:

Best

Your rotor may hold up, but that much mast puts an awful lot of stress, on it.

... And the attachment points where the J-pole bracket and building join.

Yeah, kind of a small footprint.
I guess I was giving somebody the benefit of the doubt, that they hit a truss w/ two bolts.

Well when I put that up I had a very small antenna and no rotor. It escalated from there. I can't believe it hasn't blown over or fallen off especially because the past few days have been very windy and rainy. I have checked on it, it's still in there just as good as it was the day I put it up which is amazing.

I only mention it, cause there's no worse feeling, than bent elements, except maybe,for that first dent in a new car.

Any damage to antennas I've ever had, were usually when hoisting it up, or taking it down.

I'll sure it further when it stops raining.

I'm considering returning the second FM6.

I sold the Stacker but I just realized I have nothing to ship it in. I considered buying the Winegard HD7698P and placing it under the FM6, not directly under but maybe 4 feet down. The antenna is VHF-hi/UHF so I wouldn't think it would interfere. Then maybe I'd have a box to ship the stacker in.

Excellent, you sold that Stacker faster than expected!!

If you do decide to go with the 7698, keep the mast length 5 feet or less above the rotor. Mount the 7698 no more than 1-2 inches above the rotor to help keep the torque loading to a minimum. The recommended mast length is usually 3 feet or less with light duty consumer grade rotors as they cannot withstand twisting forces like a heavier duty rotor can.

Have you considered a tripod or chimney mount? Not sure if that eave mount will be able to handle the extra load?

Best of luck when you take that Stacker down to the post office or UPS store to ship it. Be prepared for "oversize" shipping rates.

I took the Sony X3HD on the roof and performed a direction comparsion with 1 FM6 vs. 2. It didn't seem to have much of an affect on 88.7 CIMX other than RDS was always displayed with 1 FM6 and sometimes with two. 101.1 WRIF was fuzzy with two antennas. So I pointed the lower FM6 at Fort Wayne. 101.1 WRIF was clearer with two antennas (one pointed at Fort Wayne) but still not as clear with just. 88.7 remained consistent, and also added 98.9 WBYR which I liked.

In the end, I ended up taking one FM6 down, it's just better with one. If I ever want to listen to 98.9 out of Fort Wayne I can just rotate my antenna or get in the car.

I'm thinking the Antennas Direct 91XG or Winegard HD 7698P. The Antennas Direct has more reviews, not sure which one would be better for UHF. The Antennas Direct is also much shorter.

Great...