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Discussion Starter #1
Does the 91XG come with a boom extension?

What's the difference with, w/o?
 

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No extra boom with the 91XG . Wish it did for testing purposes but it consists of 3 booms , 93 " long . I am tempted tho to purchase another 91XG and add the middle boom to the existing 91 . The remainder 2 booms and components i would save as a backup ant. in which it would be now called the 43XG . Thats the diff. between them (the middle boom). The reason i would do this is because there is a ridge 1/2 mile away from me blocking the line of site needed to recieve Buff. and Toronto stations . So i`m only good for Erie and Cleveland stations . Of course i want more channels . I`m very impressed with the distance i`m picking up , 120 mi. plus but i cant seem to get the distance for Detroit way . I`m quite curious if adding another section will help me out with this. I`m not worried about ridgibility because the 91XG has it already and by adding extra length you can place the mounting bracket further down the boom where one would see fit .
 

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Discussion Starter #3
Sounds like an interesting experiment!
 

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My guess is not much will be gained, maybe around .5 dbi, if pointed right. The XG91 already has enough directors to the point of marginal utility.
 

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Discussion Starter #6
What if the directors or reflector was increased in size?
 

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I added a boom section to my 91XG. It seemed to help somewhat but it was nothing earth shattering. My next mod is to try adding mesh to the corner reflector.
 

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Increasing the reflector size would be the easiest way to get more gain on it for the lower uhf channels. But it would have to be carefully modeled so the SWR doesnt go sky high.

Changing the directors size would also generally mean changing all the spacings too. Thats a ton of work on something like the XG91, heh.


The bandwidth of a Yagi can be increased by sizing the reflector for the lowest frequency of the band while sizing the directors for the highest.
http://www.hdtvprimer.com/ANTENNAS/types.html
 

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Hi All:

I have a 91XG in my attic, and it provides reliable reception (including during mid-day) out to around 50-55 miles. I have a few stations at 55-65 miles that come in better at night but pixelate or drop out altogether during the mid-day. I was trying to get these additional stations while still keeping the 91XG in my attic if possible, so I called Antennas Direct (at the suggestion of a few others on these boards) to request an additional middle boom section. The people at Antennas Direct were very nice and helpful, and when I explained what I was trying to do, they readily sent me an additional middle boom section at no charge. I suspect that others could do the same, especially if you explained that you're a regular on these message boards.

I added the middle boom section last weekend, but the results were inconclusive (still have some more testing to do). The additional boom section tends to cause sagging in the boom, which gets it somewhat out of alignment. I was going up in the attic a number of times to adjust and readjust, and I thought that it increased the signal strength on one of my medium-range stations from 87-88 up to maybe 90, but then I moved the antenna a little and it was around 85 thereafter and I couldn't repeat that result. I was not able to get any of those 55-65-mile stations to come in reliably during the mid-day, but I'm not done testing things just yet.

I currently have the boom support above the main boom, causing the ends to sag quite a bit with the additional boom section. Next, I might flip that and support the main boom from underneath, to see if I can get any decent alignment in the boom. The tilt mechanism in the attachment bracket is complicating things a little as well, so I might see if I can just remove it to simplify things. When I get the chance to make those changes and test out the signal strengths again during the mid-day, I'll report back to the group.

I had also heard that increasing the reflector size might help as well, but I wasn't sure how much you'd need to increase the size. Was thinking about maybe putting some aluminum foil over some pieces of cardboard and putting them right in front of, or behind, the existing reflectors and seeing if that made any difference.
 

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Some great feedback here . Thanks guys . The sagging of the extended boom
isn`t sounding good . I`m assuming gcd your moving the boom mount down the boom to try to compensate for the extra length and weight . I`m still interested in the idea of bigger reflectors to improve gain abit to help with the fallout of some stations. With this in mind i ended up moving the Cm7777 preamp as close to the ant. as possible and adding alittle more tilt to the boom . Did a manual scan moving the rotor box 2 increments at a time , time consuming but i doubled my channels pulling in Buffalo fairly well and pulling in stations from Detroit which are in & out depending on time of day . I`m even pulling in a station from Lansing Mich measuring 193 miles away , not sure if thats running through a repeater in Detroit . I`m so impressed with this 91XG and CM pre-amp (only 25' in the air) I highly recommend this set up to anybody far from transmitters . Money well worth spent in my eyes . I recieve now a total of 48 digital channels and 21 of them are HD . Not bad for being in the boonies . I have a few pics of my sey up in my profile . Love this forum !!!
 

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I did move the boom support somewhat toward the front end of the 91XG after adding in the extra middle boom section. First, I put it where it would balance out the weight evenly between the front and rear ends of the antenna. But at that spot, the front mount for the boom support was still behind my second (from the front) boom connection, which really made the front sag. So I moved it forward in front of that boom connection point, which resulted in more weight at the rear, so that the 91Xg then tilted somewhat upwardly at the front, but with the boom sag more evenly distributed at both ends. I tried to fix the tilt with the mast bracket, but I had trouble with that.

My testing isn't done yet (just haven't had the time to work on it more). I think I could still get this to work right. My boom support right now is above the boom, which isn't any good, I'm now convinced. I had it this way because I was previously using a too-short PVC pipe hanging from the attic rafters that was barely long enough to reach. If the boom support were below the boom, it might work better. Also, there is only one mast clamp; if there were two (one for the boom, another for the boom support), I might be able to prevent some of the sagging by forcing clamping both to the mast.

Of course, the best solution (which I might try at some point) would be to fashion a longer boom support out of the square 1" aluminum tubing that others are using for homemade antenna masts. I still think there's a chance that the additional boom section might provide some benefit if the alignment could be straightened out.

I also plan to try the quick test of enlarging the reflectors by placing some aluminum-foil-covered cardboard in front of or behind the existing reflectors and testing my signal strength numbers before and after. Anyone have any thoughts about how much to enlarge before it would get impractical? Maybe 5 additional inches on each side (except you can't enlarge the side mounted to the boom)? If that ended up helping, outside users could use larger garden screening of some sort.

When I get the chance to mess with this some more, I'll do so, and I'll report my findings back to the group.
 

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A quick fix for the sagging boom is two self tapping screws on the top of each boom end with a piece of stainless steel trolling wire or dacron fishing line pulled taut and clamped by the screws.
 

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I`m still interested in the idea of bigger reflectors to improve gain abit to help with the fallout of some stations.
Nice install loveota!! Have you ever tried moving the antenna up or down a few "inches" in additional to tilting? Vertical fine tuning has greatly increased relaibility of difficult stations more than once for me. I usually start around 10 feet above the roofline, but surprisingly enough find better results when I lowered the antenna 6 to 12 inches. A recent install actually worked best at only 6 feet above the roof with the 91-XG. Raising it just one inch completely wiped out 1 desired station.
 

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My 91xg seems to have a weak set of rear reflectors, if I put small bolts in them thru the exisitng holes and a metal clamp with a twist screw on the back to tighten up the reflectors will it interfere with the antenna?

Also some of my directors are coming lose , Bird sits?

Can I just silicone them back into place ?

can it be combined with a cm 7777 preamp and then added to an db-8 ?

or do I need a cm4228hd moded for that ?

Thanks
 

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if I put small bolts in them thru the exisitng holes and a metal clamp with a twist screw on the back to tighten up the reflectors will it interfere with the antenna?
Keep the metal pieces small. Plumber Goop/Locktite Plumbing and Marine adhesive dries harder and holds better than silicone sealant for that purpose. Its also as electrically inert as silicone sealant.
 

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Discussion Starter #16
Increasing the Life of the 91XG

So for those with new 91XGs, is it recommended to seal all fasteners/joints with a lock-tite substance- to increase durability/longevity?
 

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Antennas Direct 91XG Hardware Hacks For Better Performance

Instead of extending the boom, I would try adding a second slightly larger 1" X 2" mesh screen behind the existing corner reflector with the horizontal wires offset to make a 1/2" gap. I tried it on my 43XG and it made a substantial improvement.

I'll climb my tower and try it on my 91XG and report back.
 

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I added a boom section to my 91XG. It seemed to help somewhat but it was nothing earth shattering. My next mod is to try adding mesh to the corner reflector.
Well, I tried adding a second piece of 1" X 2" mesh from a 4221 clone to my 43XG (which is my second 91XG with a boom section removed).

The mesh is 20" wide by 36" long.

Picture here:

http://www.digitalhome.ca/forum/album.php?albumid=211&pictureid=1411

I compared it to the regular 43XG in the exact same position on my test tripod approx. 15 ft. up. All tests with a CM7777 amp.

The results were quite impressive. My signal strength went up by varying degrees with the most noticeable change on WGRZ which is real 33. I have consistant 70 - 95 on this channel which matches my extended boom XG91 30 ft. up with an RC 9260 amp. Before the extra mesh, 33 was from 60 - 82 signal strength on the test setup.
 
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