After reviewing this forum, the Terrestrial Digital 91XG / Winegard YA-1713 antenna combination appears to be very well regarded.

Post your images of stacked 91XG + YA-1713 antennas here.
Also, please include images of your installation process and/or close-ups of key installation tips.

Feel free to also include similar combinations including:

91XG / Blonder Tongue BTY-LP-HB
Twin-stacked 91XGs
Twin-stacked 91XGs + Twin-stacked YA-1713
Winegard HD-9032 / YA-1713

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http://farm4.static.flickr.com/3312/3639689317_8172d424bc_o.png

http://farm4.static.flickr.com/3179/2659166048_2cd25d1330_o.png

Sharp looking install, very clear image, well annotated, comprehensive documentation, and a perfect blue sky too! :)

I noticed the tree in the background. Do you have any DTV multi-path interference issues?

I noticed the tree in the background. Do you have any DTV multi-path interference issues?Not for the locals and from the main antennas. Fortunately, there is a gap between two trees in the direction to the local transmitters for the main antennas. There is two antennas in the attic, a VHF that is used for local FM and a combo UHF/VHF used for the master bedroom. The lower power stations can have some signal variations but there are not that many dropouts. The channels of main interest does not have any problems with signal level.

The large outside antennas was needed years ago when the new DTV stations were low power. At the time the antennas were used with a pre-amp and fed a single MIT MDP-100. After they raised their power many other devices were added and the pre-amp was removed.

91XG + BTY-LP-HB (http://www.avsforum.com/avs-vb/attachment.php?attachmentid=127816&d=1230477714)
Courtesy of DEEPFRINGEGUY (http://www.avsforum.com/avs-vb/showthread.php?p=15395903#post15395903)

91XG + YA-1713 (http://www.avsforum.com/avs-vb/attachment.php?attachmentid=110335&d=1210740267)
Close-up (http://web.presby.edu/~jtbell/TV/images/91XG+YA1713b.jpg)
Courtesy of jtbell (http://www.avsforum.com/avs-vb/showthread.php?p=13862720#post13862720)

91XG + HD8200P (http://www.avsforum.com/avs-vb/attachment.php?attachmentid=76461&d=1172583648)
Courtesy of Rick0725 (http://www.avsforum.com/avs-vb/showthread.php?p=9889399#post9889399)

Twin 91XGs + Funke VHF
The Monster.pdf (http://www.avsforum.com/avs-vb/attachment.php?attachmentid=115033&d=1215706659)
Courtesy of PCTools (http://www.avsforum.com/avs-vb/showthread.php?p=14260430#post14260430)

Twin 91XGs (http://www.avsforum.com/avs-vb/attachment.php?attachmentid=123729&d=1225950129)
Courtesy of paris_tn (http://www.avsforum.com/avs-vb/showthread.php?p=15014464#post15014464)

91XG and YA-1713
Courtesy of Yensid (http://www.highdefforum.com/846418-post8.html)

Various rigs in general from oldest to newest.

More.

+More.

Wow, that's quite a collection of stacked antennas.

With all your experience, have you found a particular antenna that is better able to minimize DTV multi-path interference for:

VHF-hi?
UHF?
Trees are a fact of life in our neighborhood.

Thanks

Well, in general, multipath rejection requires high gain, narrow beamwidth, and high f/b ratio. Horizontal stacking for both uhf and hi-band vhf best fulfills these requirements in my experience. The best stacking distance (spacing) produces a large and narrow forward lobe, deep adjacent nulls, and sidelobes which aren't so large as to produce problems. Spacing distance =51/BW where BW is the beamwidth in the plane of the stack. (This according to J Reisert see http://www.astronwireless.com/topic-archives-stacking-yagi-antennas.asp.) I've experimented ad nauseum but always seem to come back to right around what Mr. Reisert's formula calculates. This also jives with the distances Televes recc's for its DAT75. See http://www.televes.com/hojastecnicas/103758.pdf.

I'm in the deep fringe but also have multipath issues (at least based on analog signals from the past) presumably due to local mountainous terrain and lack of LOS from the majority of my "local" transmitters.

Trees are a fact of life in our neighborhood.

Thanks

I think the effect of local vegetation is overrated. I don't mean to say there isn't some attenuation due to trees but I think the spring/summer reception issues are more likely multifactorial and more often than not are due to variable tropospheric conditions rather than leaves.

Here's a pic of my antenna pointing at 350 degrees. At this position I receive a DT-31 at 67 miles consistently without dropouts and a DT-13 at 77 miles consistently but with dropouts. When the leaves drop things don't really change appreciably for DT-13. I'll have to let you know what happens with DT-31 as it is just a recent change from low band vhf DT-4.:) BTW both of these are listed as "tropo" reception for my location according to TVFOOL.

I think the effect of local vegetation is overrated. I don't mean to say there isn't some attenuation due to trees but I think the spring/summer reception issues are more likely multifactorial and more often than not are due to variable tropospheric conditions rather than leaves.

Here's a pic of my antenna pointing at 350 degrees. At this position I receive a DT-31 at 67 miles consistently without dropouts and a DT-13 at 77 miles consistently but with dropouts. When the leaves drop things don't really change appreciably for DT-13. I'll have to let you know what happens with DT-31 as it is just a recent change from low band vhf DT-4.:) BTW both of these are listed as "tropo" reception for my location according to TVFOOL.

One picture is worth a thousand words!
91XGs?
What are the two VHF antennas? How far above the roof peak are they?

No. They are Triax Unix 100A's and are band-specific for uhf 14-38. The gain drops like a rock above channel 40.
See http://www.njal.no/Doc/Triax%20produktinfo%20antenne%20100element.pdf
On the gain graph at the bottom the "Band A" model is the left-most trace. The right-most trace is the Unix 100W and should be roughly equivalent to the gain of the xg91. The screening I added to the reflectors is "worth a try". It seems to increase f/b ratio in my experience and may help with both multipath rejection and overall performance. It's 1/2 inch galvanized mesh available at Lowe's and is cut-to-fit and attached via wire ties.



The bottom are Antennacraft Y10 7-13's and are about 18 inches above the roof peak.

How far below the UHF array are the Y10 7-13's?

38 inches center-to-center. Around 30 inches metal-to-metal. For channels 10 and above, 30 inches metal-to-metal is plenty. If you have a channel 7 or 8 you may need 36 metal-to-metal.

Your pictures, descriptions and personal results have been very enlightening. :)

Recently, I read elsewhere that it was "necessary" to have an antenna at least 10 feet above the peak of a roof for the best possible reception. Such a "requirement" is obviously more involved with stacked separates on a roof-mounted mast compared with an all-in-one combination antenna.

Whoever told you that apparently doesn't know about the boundary gain you can get from the surface below. The roof surface can actually be an advantage in some situations. Higher is often better, but not always. In my situation, the signal actually is significantly worse beginning around 7 feet or so above the roof.

I'm familiar with the boundary effect for microphones. I was not aware it also is applicable to TV reception. How did you determine the optimum height above your roof for the greatest signal strength - a telescopic mast and a meter &/or a monitor?

Telescoping mast and multiple trial/error.

Whether it's boundary/ground gain/roof surface interaction or whatever, there's no doubt the effect is there for me.

Here's something on ground gain:
http://www.qsl.net/oz1rh/gndgain/gnd_gain_eme_2002.htm

Thanks for the link cpcat. Is there a particular brand of telescoping mast you like?

I use the 30 foot (18 guage I think) CM model for no particular reason other than Lowe's carried them at the time that I bought one. I've had no problems with it and it works fine. I installed it upside down with the thickest portion at the top for added strength/stiffness.

Top is Y10-7-13 and the lower quad has four CM4248's. Others are for ham radio.
John

ctdish,
Did you pour Miracle-Gro on your tower? :)
Did I hear someone say Antenna Farm?

Now that's some metal in the air.:)

There has to be a big ham rotator doing duty. I've often wanted a heavier duty rotator but
have always been stopped by the lack of remote control capability (other than through a PC). I also currently only have 5-conductor wire in place and it would be somewhat of a hassle to have to pull another wire.