The Official AVS Antenna and Related Hardware Topic! - Page 201

I've got a channelmaster that I've had for about 16 years. I've got a radio shack preamp on the mast. I'm not sure what model either of these are unfortunately, but the antenna is about 10 feet long. Looks like a crossfire in the newer models. I have directv with an HD Tivo, but I also have a couple of sets just hooked to the antenna so it needs to do more than just high UHF.

I can pick up 2,4,5,7, 44 very clearly in HD out of boston, but Fox 25 in HD is very sporadic. Most of the times there is not enough signal to get a picture. This hasn't bothered me so much but I've got this large front projection screen now and the 2007 super bowl will be on Fox. What do you recommend I do to try to pull in Fox 25 in HD?

I've actually got an unused new rotor that's been sitting here for a couple of years in my basement. I got directv and never bothered to put it up. But there is no other fox in the area so I don't think that will help.

New antenna? New amplifier? Both? The easiest thing for me to do would be to pick up a new amplifier and try that first, but frankly I have a feeling the Rat Shack model isn't all that bad. It sure makes a big difference when it is not in use.

-steve

Also, my zip is 01462 and I think I'm about 30 miles west of the HD transmitters in Boston. Antennaweb for my address doesn't even list the stations I can get quite clearly!

You could be having multi-path problems with the WXYZ-DT ABC 7 (41) station. Or it could be signal fluctuation because of moving trees & leaves. Looking at a antennaweb list for Detroit, the broadcast towers, with the exception of combined CBS, PBS, MNT tower are at different locations. If you questions about the station, go to the Detroit thread in the Local Reception forum. First step is to try different aims for the antenna. Then if that doesn't work, tell us what antenna you have, indoor or outdoor setup, and post your zip code so we can evaluate whether you have the right antenna for your situation.

Also the Samsung SIR-T351 is several generations old. The new Samsung DTB-H260F is getting a lot of positive reports for locking in stations that were frequently not solid with older STB ATSC tuners. But a new $180 ATSC STB is the expensive route. Try tweaking the antenna setup first.

Check with the Boston OTA thread (http://www.avsforum.com/avs-vb/showthread.php?t=28454) for info on the Boston WFXT-DT Fox station. The FCC database (accessible through http://en.wikipedia.org/wiki/WFXT) for the digital signal shows a licensed power of only 78 KW. There is an application for a full 1000 KW, but I recall seeing posts before about the Fox station in Boston being at not very high power.

Antennaweb.org is very conservative on digital reception. Try entering your address, but this time click on the options link and enter a height of 100 or 200 feet or even higher. See what digital stations now show up on their list. As for the Radio Shack pre-amp, the Channel Master and Winegard pre-amps are regarded as the better brands.

The superbowl will be on CBS this year.

Hi,

Thanks VERY much for the reply! I have posted a similar
question over at the Detroit thread.

Multipath eh? So (I am new to this so plz forgive newbie
HDTV questions!) that would be coherent interference
between the xmitter-antenna signal and the
xmitter-SUV_in_the_street-antenna signal? If so, kind of
weird that it does not affect the other channels, unless
the extra xmitter-street-antenna distance just happens to
be a diabolical multiple of pi/4 wavelengths at the ABC
frequency but not the other channel frequencies?

I am using an antenna that was left in my garage by the
previous owner of my place. He left it up on the studs in
the top part of the garage so I just turned it towards the
Detroit broadcast cluster (I am zip 48105, so I tried to
get it about 65 degrees E (CW) of N -- I hope I interpreted
the antennaweb information correctly). It is a Channel
Master (maybe 10' long, w/ some rust so prob. pretty old!).
I am running it inside to my basement -- prob. about 50'
of coax before it gets to the T351. As it turns out, I
borrowed the T351 from a friend of mine at work just to
see if I could receive HD over the air, so now that I am
hooked I need to go out and get a receiver pretty
quickly anyway to avoid abusing my friend's kindness. I
can easily pick up a DTB-H260F, prob. this afternoon
(if not sold out at local BestBuy/Circuit City).

Thanks again, I can see why everyone is so excited about
HD, what an amazing picture ....

Hello

I would like some of your opinions on which antenna would be best for me. Here is the info from antennaweb.org. I contacted solidsignal and they recommend the Ch 6371 I think that might be more then what I would need plus that antenna is huge thats my problem with it. I hoping the ch4228 will work. I have a little B&W tv out in the garage that has just a stick antenna and I'm able to pick up 3 channels with some snow. I'm looking to get HD channels

blue - vhf WCCO 4 CBS MINNEAPOLIS MN 221° 47.8 4
blue - uhf WCCO-DT 4.1 CBS MINNEAPOLIS MN 221° 47.8 32
blue - uhf WFTC 29 MNT MINNEAPOLIS MN 221° 47.5 29
blue - vhf KTCA 2 PBS ST. PAUL MN 221° 47.5 2
blue - uhf KTCI 17 PBS ST. PAUL MN 221° 47.6 17
blue - uhf KPXM 41 i ST. CLOUD MN 257° 61.0 41
blue - vhf KMSP 9 FOX MINNEAPOLIS MN 221° 47.5 9
blue - uhf WUCW 23 CW MINNEAPOLIS MN 221° 47.8 23
blue - vhf KARE 11 NBC MINNEAPOLIS MN 221° 47.8 11
blue - uhf KSTC 45 IND MINNEAPOLIS MN 221° 47.8 45
blue - vhf KSTP 5 ABC ST. PAUL MN 221° 47.8 5
blue - uhf WHWC 28 PBS MENOMONIE WI 140° 47.2 28
violet - uhf KSTP-DT 5.1 ABC ST. PAUL MN 221° 47.8 50
violet - uhf KARE-DT 11.1 NBC MINNEAPOLIS MN 221° 47.8 35
violet - uhf W24CL 24 PBS GRANTSBURG WI 0° 18.2 24
violet - uhf KMSP-DT 9.1 FOX MINNEAPOLIS MN 221° 47.5 26
violet - uhf WFTC-DT 29.1 MNT MINNEAPOLIS MN 221° 47.5 21

Thanks

>> The superbowl will be on CBS this year.

Hey you're right Tower Guy. I misread the superbowl site and was looking at the wrong year.

afiggatt - Thanks for the pointers. Maybe Fox will be boosting their signal in the future. It sounds like I should do the easy thing first and upgrade the amplifier.

thanks,

steve

So if you just want digital channels, antennaweb shows KSTP-DT ABC, KARE-DT NBC, KMSP_DT FOX, and WCCO-DT CBS. They are all on UHF today. But KMSP will be going back to channel 9 and KARE back to channel 11 when analog goes away in 2009. Your two PBS stations in Minneapolis don't show up but they may still be in the antennaweb database as low-power.

The recommendation for the 3671 is not a bad one if you want to receive the analog VHF stations between now and 2009. For the UHF digitals either the CM4228 or the Antennas Direct 91XG would be a better choice, mounted outside as high as you can, coupled with a CM7777 preamp. Both these antennas are UHF but with some performance on VHF-hi as well, but in 2009 when analog goes away you will probably need to add a VHF-hi antenna to get KARE and KMSP, maybe you can worry about that when it happens. There are a couple of VHF-hi antennas around and you may see more of these as 2009 approaches.

Thanks for all the info. The analog VHF stations are not that important to me so I will try either the 91XG or the CM4228.

I am installing a channel master 4228. All of my signals come from different directions. My question is should I install a pre-amp? One of my towers is 15 miles away the other is 35 miles away in opposite direction 15 degrees compared to 165 degrees compared to due north. I have a old small yagi on a 20' pole right now that will bring in the station 35 miles away and also pick up the other station on the backside with no pre-amp. The 35 mile station is at 57 signal strength the other at 72. I realize and hope the 4228 will get better gain than this old yagi I have straped up there that I actually dismantled from a 20 year old uhf-vhf antenna. The yagi is sorta pointed upwards also instead of being straight. The 57 signal strength will try to pixil sometimes. I have a channel master 3041 DSB pre- amp that I paid 30 dollars for at Lowes. Will a pre-amp cause me problems? I am hoping to pick up the strong station from the backside of 4228; I am doing this now with this yagi. I also might be able to pick up shreveport Louisiana with 4228 but will need pre-amp because I am 70 miles away. Will pre-amp cause problems when some stations are real close but needed for far away stations? If I install pre-amp do you suggest using 300 ohm twin lead from antenna to pre-amp? This pre-amp has a 300 ohm input. I have heard that matching transformers will cause a 2 db loss which would give me a 4 db loss before I ever hit the pre-amp. I have some good300 ohm twin lead. If I can pick up Shreveport I will install rotor later.
Thanks
Smackman

Try it first without the pre-amp. If you are satisfied leave it that way.
It could. Many pre-amps overload easily in the presence of strong signals.
Might work. Try it.
I use a 4228 with a preamp to pick up several stations from 70 to 75 miles away. But, I don't get 24/7 reception from any of them. I have two other stations at 90 degrees from where the antenna is pointed that are only 25 miles away and I get good reception from them all the time.

I get 60mile plus channels from the backside of my 4228. But in direction of hills, only the 91xg will zero in. I can leave the 4228 in one position and get 95% of my channels. Site specific requires use of both. Over the hills, the 4228 drops out every 20 seconds but the 91xg will give me a 60 to 90% reception. Sometimes you need both to tame the multipath beast.

Completely flat terrain and very few buildings (there is a 2 store house next door). Information on anntenaweb. Most stations are UHF between 84-88 degrees and 10-12 miles. The majority list the color code as "yellow." Will the DB4 in the attic perform well? Most lower frequncy vhf stations are analog and have a UHF digital showing the exact same content so this antenna will pick up nearly everything listed at antennaweb save 3-4 out of about 37 stations. Actually pretty much all of the vhf stations are analog and have a digital version on UHF. Except for one 50 miles away in Conroe I can live without. And channel 8 (PBS) on frequency 9 thats 11.7 miles away. I can live without that and/or watch it on sat if needed.

I'd say directional at 86 degrees would be good but I don't know how that would work in the attic. I really don't want to pay someone to mount it on the roof.

BTW attic is pretty thin because its a newer house but there is a radiant barrier.

Is this with the screens on or off? I have stations coming from all directions, but the ones I'm mainly interested in come from the S. southwest, 60 miles and the north
at 25 miles and 41 miles. One of those at 41 miles is VHF on channel 10. One person
in my market gets the VHF at over 90% with the 4228. So if I was to get this antenna, would I be able to point it southward and still receive the stations to the north with it reliably? Right now I have two antennas joined together pointing in
these directions, but am missing one NBC channel to the south at 55 miles.

Thanks for the advice.

Screens on. Use CM pre amp 7777. Alot depends on topography and if you're joining antenna, be sure to do it correctly, as it's a science. A good rotor is handy.

Have you considered the use of an additional antenna and a channel 44 Jointenna for WECT-DT?

I join two antennas now with a splitter in reverse and get all Wilmington channels strong with the exception of WECT. It works in the evenings and mornings occasionally. All other channels (both WIlmington and Greenville) come in perfectly the way I have it set up now. I use a CM pre- amp after the splitter. I was thinking the 4228 might be enough to get WECT also- I just
don't want to lose the others, and would like to use just one antenna if possible.

Wis Dells Need Staitions About 60 Miles Away, Have A 40 Ft Tower With Rotor And An 1985 Antenna. Out In The Woods I Think The Trees Are The Problem. Do I Need A New Antenna And A Amplifier? What Are My Options And About How Much Should I Spend???

Hello. Need some advice on antenna selection, if pre-amp will be needed, and if my distance is too far to even attempt an attic install. Here are the specs from antennaweb:

blue - uhf KTBO 14 TBN OKLAHOMA CITY OK 292° 36.9 14
blue - uhf KOCM 46 IND NORMAN OK 294° 37.9 46
blue - uhf KOKH 25 FOX OKLAHOMA CITY OK 289° 36.4 25
blue - vhf KFOR 4 NBC OKLAHOMA CITY OK 291° 37.0 4
* blue - uhf KFOR-DT 4.1 NBC OKLAHOMA CITY OK 294° 37.9 27
blue - vhf KETA 13 PBS OKLAHOMA CITY OK 289° 36.8 13
* blue - uhf KETA-DT 13.1 PBS OKLAHOMA CITY OK 294° 37.9 32
blue - uhf KTUZ 30 TEL SHAWNEE OK 256° 25.0 30
blue - uhf KAUT 43 MNT OKLAHOMA CITY OK 293° 37.4 43
blue - uhf KSBI 52 IND OKLAHOMA CITY OK 271° 33.4 52
blue - uhf KOCB 34 CW OKLAHOMA CITY OK 289° 36.4 34
* blue - uhf KOCB-DT 34.1 CW OKLAHOMA CITY OK 290° 36.5 33
blue - vhf KOCO 5 ABC OKLAHOMA CITY OK 290° 36.8 5
* blue - vhf KOCO-DT 5.1 ABC OKLAHOMA CITY OK 290° 36.8 7
* blue - uhf KOKH-DT 25.1 FOX OKLAHOMA CITY OK 289° 36.4 24

Distance between 33-38 miles on flat land, no obstructions. Compass orientation within 5 degrees to all but one independent channel which is 23 degrees off main stations. ABC is the only vhf station. Would like to not break the bank if possible but make sure I have enough antenna to do it right the first time (within reason). Thanks for the help.

If you don't have obstructions in the attic such as metal ducts or metal liners, 33 to 38 miles should be doable for an attic antenna. I get stations at 43+ miles with a CM 4221 in my townhouse attic and I have local obstructions of the tops of other townhouses to contend with.

You have KOCO-DT broadcasting on VHF 7 with a confusing set of entries in the FCC database for it's power level (see http://en.wikipedia.org/wiki/KOCO and click on FCC database link). You will need to select an antenna which work for both UHF and upper VHF. The CM 4228 may work, but it rather large for an attic. With all the stations in the same direction, a more conventional VHF/UHF antenna is probably what you should look at. Antennas from Winegard and Channel Master for starters.

If you provide your zip code and some details on the current antenna - model, VHF, UHF? - we can respond with some more helpful suggestions. If the 1985 antenna has a UHF antenna and is in good condition, maybe you should try it to see what digital stations you can get with it if you have a TV or STB with a ATSC tuner.

Hi, just got my first HDTV set yesterday & am trying to upgrade my surrounding setup. One of the first things I'm tackling is a new antenna system, and would appreciate any advice. Because we don't get cable or dish, I'd be relying on it for all our viewing except DVD, so I am willing to do what it takes, within what I am able due to my circumstances (see below).

One of the things I'm trying to find is some kind of comprehensive comparison review of HDTV antennas. I've googled & looked through a few of the 107+ pages of this thread (!) but haven't found anything yet. Any pointers for that genral advice/info appreciated!

More specifically, I discovered antennaweb & inputed my location, & obtained it's recommendations; I have attached the map it generated to this post. A couple comments on this:

1. It got my location slightly wrong; I put the actual house location on as a red square if it matters
2. based upon this, I think I have an exceptionally clear horizon to the towers. I live just off a golf course, and the directions on the map go right through a large gap between two houses that immediately adjoin the course, then there are no other buildings for at least 600 yards.
3. My house is a 2 story and the roof/attic is higher than any trees along those lines between me and the other end of the golf course
4. However there is a water tower about 1600 yards away, along the general direction of the line to the towers. It is the only structure of any significantly greater height in those general directions for a couple miles at least.
5. The terrain in my part of the country is very flat.

As you can see on the map, I have two sets of towers I want to pull in, but all in a driection within six compass degrees, so I'm hoping whatever works for one works for all. Here is the tabular output from antennaweb recommendation to accompany map (I wish i could put it in an html table fot make it easier to read but don't see that I can in this forum software):

First a request for confirmation/clarification: it surprises me that some channels are listed as uhf; I was under the impression that some would be vhf, according to channel number (2-13 vs 14+)? Does this mean I only need a uhf capable antenna, I don't need to worry about vhf reception???

Finally, my personal circumstances: This is a 2-story condo townhouse that we rent, so I may have some limitations regarding roof/eaves mount -- I can talk to landlord if necessary, but if it's possible to make this work with an indoor/attic setup that would be preferred. The room the set is in has a cathedral ceiling, all the way up to the roof (no attic in this part of buidling), so I think mounting to the ceiling of the room somehow (if the antenna is not too big/ugly) would be equivalent to an attic mount? This room is in the back of the place, i.e. facing the direction of the towers I want to pick up, the signal would only have to travel through the roof (no attic in htis part of the house).

So far from preliminary investigation I am wondering if the Philips MANT950 might work for my circumstances. There is an intruiging review at epinions that seems to match my circumstances, and it looks unobtrustive enought for a cathedral ceiling mount (thinking near the hightest point, so at second story ceiling, effectively). But then again, it's just an epinions review, nothing normalized. Here is the complete text (since as a new user, the forum software won't let me link to it):

Any advice or comments on my thinking would be greatly appreciated!

Thanks for the reply. AntennaWeb says I need a medium directional with pre-amp. What is the difference and pro's/con's of getting an amped medium directional vs. a large directional w/o a pre-amp. Or am I barking up the wrong tree? ABC KOCO-DT on vhf 7 broadcasts at a 100 kw and will be most likely my toughest challenge. Knowing this, does this change any antenna strategy or will it come down to trial by fire. Appreciate any help.

1. For Antenna Comparisons, see fol. avsforum thread re antennas,
rotators, preamps, etc. (which includes below highlights):
http://www.avsforum.com/avs-vb/showt...96#post5711296

2. Esp. be sure to click on the three "Heavy Metal" and ATech Fabrication
long distance on-air comparison tests:
http://www.atechfabrication.com/reception_solutions.htm.

3. Links to Bob Chase's on-air outdoor vs indoor comparisons for eight antennas,
incl. an attic placement investigation:
http://www.avsforum.com/avs-vb/showt...2&#post6245872
http://www.avsforum.com/avs-vb/showt...71#post5399471
http://www.avsforum.com/avs-vb/showt...32#post5410432

4. Link to NEC computer simulation studies:
www.hdtvprimer.com/ANTENNA/comparing.html

5. Kerry Cozad's antenna on-air test range results for a few selected antennas:
http://hdtv.forsandiego.com/messages...tml?1126051755

6. Attached is my updated spread sheet, summarizing/plotting manufacturer spec sheet info,
as well as some of Kerry Cozad's measurements....

 

DTV_Antennas_RevD-3875.zip 22.6435546875k . file

I'm using a pretty inexpensive roof-mount Radio Shack UHF/VHF antenna to tune in both NTSC and ATSC channels. The tuner is a Sony DHG-HDD500 HD PVR.

I recently developed a problem where I'm not reliably tuning in the PBS digital channels in New York City (13.1, 13.2, 13.3) but the rest of the ATSC channels are coming in fine (NBC, CBS, ABC Fox, etc.). I understand that the PBS channels are lower power than the rest, but a roof antenna 1.5 miles from the transmitter on the ESB (direct line of sight) should be able to tune it in.

I have a standard 300ohm-75ohm transformer connected to the antenna, RG6 cable running down maybe 75 feet to a splitter (in the house) where I'm splitting the signal once (1-to-2). I find that if I disconnect one of the 300 ohm leads at the antenna, the signal improves (visible on analog channels), though not enough to lock into the PBS digital channels. Could this be caused by some kind of grounding problem on the antenna itself or the mast? Or is it more likely to be a cable or connector shield fault?

I initially had two feeds hooked up directly to the antenna, each running to different parts of the house, but recently disconnected the second feed to try to beef up the main feed. The frustrating thing is that the second feed which is now disconnected from the antenna entirely (just a dangling 75ohm-300 ohm transformer on the roof) is actually tuning in the PBS channels fine without an antenna but with a channel Master amplifier! I tried this with the other feed but it was not strong enough to pick up the PBS digital feed from the ATSC receiver in our living room.

Is it likely to be a problem with the antenna itself or the cabling? I have a section of the RG6 cable plastered right into the wall so I'm hoping it's not the cable. I'm tempted to just buy a better UHF-only antenna and see if this works better, but would appreciate any suggestions from the antenna gurus.

Thanks,

-Chris

It's most likely a multipath problem, Chris. Try turning your antenna a few degrees one way or the other. It can make the difference between great signal and no signal if multipath is part of the mix.

Good luck!

Larry

Also, try an FM Trap on the antenna line. At that distance, there will likely be overload from any FM stations nearby. That can cause noise and distortion byproducts that mask the lower-powered signals.

I've really been itching to do a quad of DAT 75's. I have a Lindsay 2 way combiner so called up Lindsay to order a 4 way model. Lindsay UHF/VHF combiners

Guess what? They no longer manufacture them. Called fellow AVS'er MaxHD to see if he could help and although he didn't have a source for the 4WCU, he did have a couple Televes ref. 5006's on hand which are basically preamp/uhf combiners all in one. Televes ref. 5006 I figured maybe I could use them with a power passing splitter to do the quad. I ordered the DAT 75's from cpc with the usual 7:00 a.m phone call due to the time difference.

Guess what? The DAT75's now have redesigned larger reflectors (presumably for added gain in the lower uhf). Needless to say, I was a little dissappointed as I wanted 4 identical antennas. I decided to try anyway though. In the meantime, I called/emailed Lindsay again (acting more desperate this time) and an extremely helpful person there found a 4WCU for me . Through all of this in the last month or so, I've been trying various combinations for this setup and thought I'd share my results here.

Equipment:
4 semi-identical Televes DAT 75's
Research Comm. 9253 HDTV LNA with ps
Televes ref. 5006 x2 with ps x2
Lindsay 2WCU and 4WCU uhf combiners
Lindsay LS2A vhf combiner
power passing wide band uhf splitters of various brands

Initially, using the ref 5006's through a power-passing splitter didn't work very well. The performance overall was less than that of just a horizontal stack with the 2WCU combiner into the RC 9253 LNA. I suppose the phasing just wasn't perfect enough through the splitter. For novices out there, phasing is critical when combining antennas for added gain. The signals need to be identical as possible and in-phase which means everything needs to be symmetrical (i.e. equal signal paths and cable lengths) up to the point of combination.

Using the 2WCU as the power-passing splitter worked better. I'd say about equal in performance to the initial horizontal stack. Incidentally, this configuration isn't actually a quad stack. It's better termed a stack-of-stacks. No matter what the combination, it seemed that a vertical stack of horizontal stacks outperformed a horizontal stack of vertical stacks. Not sure why that is but it wasn't even close.

Using regular resistive splitters, whether 3 dual or one 4-way didn't work at all for me. Others seem to have some success using these, but I can't say they work at all.

Next up, the true quad (actually an H-quad) using the 4WCU into both the ref 5006 (using only a single input) and the RC 9253. The ref 5006 held it's own BTW against the 9253. Not sure if I could tell any major differences. The quad, however, was overall somewhat dissappointing. I tried various stacking distances and it seemed 36 inches square worked the best. There were some channels for which it seemed to perform excellent, but others were poor. I think it may be that it's difficult to phase a true quad properly for a wide band setup and this would work better for narrow-band or single channel setups. I also couldn't really get the antennas much closer than 36 inches square (due to the megareflector on the new DAT75) so it may be that the phasing would have improved at closer distances. I did figure out a way to create an identical 4-antenna array BTW. The reflectors are interchangeable so I tried it with one large and one small on each antenna. It worked, but overall it seemed to worka little better in the pictured configuration below. Also, you'll notice I've added screening to the reflectors. This improves F/B ratio and helps me with co-channel interference I have between an analog and digital 34. Anyhow, that's a whole other story.

So, needless to say, at this point I was quite bummed with the quad stack performance. I then tried using the 2WCU and the 4WCU (used as a 2-way) to combine the stacks through the ref 5006. For some reason, this just wouldn't work. The 2WCU and 4WCU are exactly the same size/length and the only internal difference that I could see is that the 4WCU has 4 f-sockets soldered inside the end of the combiner while the 2WCU only has 2. Obviously, there must be more difference than that as they just wouldn't phase at all. Maybe someone who knows how stripline combiners work can answer this?

So, almost in desperation (again), I decided to try to use the 2WCU and the LS2A to combine each stack. The stacks were then combined through the ref 5006's dual uhf inputs. I compensated for the added length of the 2WCU by adding corresponding length to the cable coming off the LS2A (actually, I tried multiple lengths and settled on 13 inches as the best). Bingo! It worked. Performance now surpassed that of the original horizontal stack throughout the uhf band. It's difficult to quantify exactly, but I'd say my performance now is overall similar from channels 14-38 to my Triax Unix 100 Band A stack. This is excellent performance in this range for a wide-band uhf setup. For channels 39 and up, I'd say better by a small margin over the original DAT 75 stack.

Obviously, the next logical step would be to replace the LS2A with another 2WCU. However, I'm not sure when one will turn up and my WAF doing all this is currently on empty.

I'll keep you posted.

Charles

I've really been itching to do a quad of DAT 75's. I have a Lindsay 2 way combiner so called up Lindsay to order a 4 way model. Lindsay UHF/VHF combiners

Guess what? They no longer manufacture them. Called fellow AVS'er MaxHD to see if he could help and although he didn't have a source for the 4WCU, he did have a couple Televes ref. 5006's on hand which are basically preamp/uhf combiners all in one. Televes ref. 5006 I figured maybe I could use them with a power passing splitter to do the quad. I ordered the DAT 75's from cpc with the usual 7:00 a.m phone call due to the time difference.

Guess what? The DAT75's now have redesigned larger reflectors (presumably for added gain in the lower uhf). Needless to say, I was a little dissappointed as I wanted 4 identical antennas. I decided to try anyway though. In the meantime, I called/emailed Lindsay again (acting more desperate this time) and an extremely helpful person there found a 4WCU for me . Through all of this in the last month or so, I've been trying various combinations for this setup and thought I'd share my results here.

Equipment:
4 semi-identical Televes DAT 75's
Research Comm. 9253 HDTV LNA with ps
Televes ref. 5006 x2 with ps x2
Lindsay 2WCU and 4WCU uhf combiners
Lindsay LS2A vhf combiner
power passing wide band uhf splitters of various brands

Initially, using the ref 5006's through a power-passing splitter didn't work very well. The performance overall was less than that of just a horizontal stack with the 2WCU combiner into the RC 9253 LNA. I suppose the phasing just wasn't perfect enough through the splitter. For novices out there, phasing is critical when combining antennas for added gain. The signals need to be identical as possible and in-phase which means everything needs to be symmetrical (i.e. equal signal paths and cable lengths) up to the point of combination.

Using the 2WCU as the power-passing splitter worked better. I'd say about equal in performance to the initial horizontal stack. Incidentally, this configuration isn't actually a quad stack. It's better termed a stack-of-stacks. No matter what the combination, it seemed that a vertical stack of horizontal stacks outperformed a horizontal stack of vertical stacks. Not sure why that is but it wasn't even close.

Using regular resistive splitters, whether 3 dual or one 4-way didn't work at all for me. Others seem to have some success using these, but I can't say they work at all.

Next up, the true quad (actually an H-quad) using the 4WCU into both the ref 5006 (using only a single input) and the RC 9253. The ref 5006 held it's own BTW against the 9253. Not sure if I could tell any major differences. The quad, however, was overall somewhat dissappointing. I tried various stacking distances and it seemed 36 inches square worked the best. There were some channels for which it seemed to perform excellent, but others were poor. I think it may be that it's difficult to phase a true quad properly for a wide band setup and this would work better for narrow-band or single channel setups. I also couldn't really get the antennas much closer than 36 inches square (due to the megareflector on the new DAT75) so it may be that the phasing would have improved at closer distances. I did figure out a way to create an identical 4-antenna array BTW. The reflectors are interchangeable so I tried it with one large and one small on each antenna. It worked, but overall it seemed to worka little better in the pictured configuration below. Also, you'll notice I've added screening to the reflectors. This improves F/B ratio and helps me with co-channel interference I have between an analog and digital 34. Anyhow, that's a whole other story.

So, needless to say, at this point I was quite bummed with the quad stack performance. I then tried using the 2WCU and the 4WCU (used as a 2-way) to combine the stacks through the ref 5006. For some reason, this just wouldn't work. The 2WCU and 4WCU are exactly the same size/length and the only internal difference that I could see is that the 4WCU has 4 f-sockets soldered inside the end of the combiner while the 2WCU only has 2. Obviously, there must be more difference than that as they just wouldn't phase at all. Maybe someone who knows how stripline combiners work can answer this?

So, almost in desperation (again), I decided to try to use the 2WCU and the LS2A to combine each stack. The stacks were then combined through the ref 5006's dual uhf inputs. I compensated for the added length of the 2WCU by adding corresponding length to the cable coming off the LS2A (actually, I tried multiple lengths and settled on 13 inches as the best). Bingo! It worked. Performance now surpassed that of the original horizontal stack throughout the uhf band. It's difficult to quantify exactly, but I'd say my performance now is overall similar from channels 14-38 to my Triax Unix 100 Band A stack. This is excellent performance in this range for a wide-band uhf setup. For channels 39 and up, I'd say better by a small margin over the original DAT 75 stack.

Obviously, the next logical step would be to replace the LS2A with another 2WCU. However, I'm not sure when one will turn up and my WAF doing all this is currently on empty.

I'll keep you posted.

Charles