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I'm about to enter the world of HDTV and would like some antenna advice. I'm approximately 65 miles NW of Phila at an elevation of about 700 feet. I need a UHF/VHF antenna with a rotor and preamp. I plan to mount the antenna on the roof. Any opinions on the Channel Master 3020? Is that more antenna than I need? Any suggestions and advice would be greatly appreciated. Thanks in advance. I will be hooking up to a DISH 6000.
 

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Quote:
Originally posted by Bromley:
Any opinions on the Channel Master 3020? Is that more antenna than I need? Any suggestions and advice would be greatly appreciated.
Bromley, I have no experience with the 3020. 65 miles is a long haul for UHF. Do a search for on this forum for Philadelphia and see what turns up.


For a rotor try the Channel Master Model 9521, available at Consumer Direct or Stark Electronics .


You can change the direction by entering the compass heading as a three digit number. Another method is to memorize the compass heading for each of your stations, then to change the heading for the desired station all you need to enter is the corresponding stations two digit number.


The IR system will emulate a couple of Pioneer products. This will allow most universal remotes to control your rotor. More info at Channel Master or this one to go direct to 9521 info



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Wendell

Technical Services Supervisor

MAETV
 

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How much of a factor are the trees with UHF? At rooftop one still has to deal with them. Do the longer Yagi's actually repel interference from them?


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hermithill
 

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You've at least got a range problem. And if you have any large structures or geologic formations nearby or in the path from Philly, you may also have a multipath (reflected signals) problem, too. To pick up UHF 65 miles out will require an antenna with a LOT of gain. If you're dealing with multipath issues, you also need an antenna with excellent multipath rejection characteristics. One point of clarification - you mentioned the CM 3020. That model's a combo UHF/VHF/FM antenna. I noted that there are apparently four digital stations on the air in the Philidelphia area - KYW, 26; WPVI, 64; WCAU, 67; and WTXF, 42. Since these are all in the UHF band, it would make more sense to invest in a dedicated UHF antenna to maximize gain in that region of the spectrum. Or, did you mean the CM 3021? That's a four bow-tie UHF-only antenna with a reflector screen. CM rates it to ~45 miles. For more gain, though, CM also lists a monster 84" parabolic dish feeding a two-bay bow-tie, the 4251, that they rate to 60+ miles. They also list a smaller 40" version, the 4228, that they rate to 60 miles. These are high gain and highly directional due to the dish reflector, but the bow-tie active elements may be susceptible to some multipath from side-lobe sensitivity. CM also makes the aclaimed 4248 80" long yagi. It's rated by them to 45 miles, but the yagi is an inherently good multipath rejector, as well as highly directional. Another company, Antenacraft, has a yagi design, their MXU59 at 100" long. It claims an accross the band 15 dB gain figure along with excellent directivity and multipath rejection. I can't vouch for it. Yet. I have one on order and it should arrive later this week. Another forum member, Murray Kerdman, reports that model was a problem solver for his unusual reception woes out here in southern California, though. Apparently nothing else locked a signal at all for Murray, but the MXU59 brings in six of the nine available digital channels. Don't take my comments as authoritive - they're not. However, I hope I've at least given you some tips to consider with enough detail in digestible form so that you're not overwhelmed with techno-babble. In the end it may be prudent to bite the bullet and pay an antenna installer to do a site survey and give you recommendations. Good luck.




[This message has been edited by Ray H (edited 05-22-2001).]
 

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Wendell, there's an 800 number on their website. I called for distributor information, but since their nominal distributor in southern California doesn't wish to stock their line, they offered to sell directly to me.


Don, while UHF is more suseptible to foliage blockage than VHF, it's no where nearly so as DBS satellite signals. DBS has two things going against it: 1> only about 250 watts of radiated power from >22,000 miles out to blanket North America, and 2> the Ku band just happens to be the resonant frequency of water (a compound green foliage has in abundance). Remember, some folks mount their UHF antennas in the attic "looking" through shingles nailed to boards - and they still manage to lock the signal just fine! Basically, TRY it to see. Anecdotally, when I first got my DTC100, I used a set top mounted "Silver Sensor". It looked through two solid walls AND an avocado tree in the front yard. For those unfamiliar with avocado trees, they're perennial - they carry their BIG, BEEFY leaves year 'round. Despite this unlikely arrangement, I managed 4 of the 9 available digital channels from ~35 miles out, unamplified. (Ironically when I converted to a RatShack 80" chimney mounted yagi, I gained two additional channels, but lost one that the Silver Sensor had managed. Amplification with either antenna made things worse. Go figure.) Oh, by the way, Wendell, if you've read this far, the guy at Antennacraft was not at all hesitant to confirm that they make RatShack's antennas when I pointedly asked him...


[This message has been edited by Ray H (edited 05-22-2001).]
 

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To Bromley:


I don't know where you are exactly, but it sounds like you are in the Berks County or Schuykill County area.


Your reception of Philadelphia DTV signals will largely be dependent on the reception path you have to the Roxborough section of Philly, where the towers are located. If the path is moderately clear to the southeast, you have a good chance.


Here are the digital stations that are currently on-air and the power levels they are running:


PHILADELPHIA


KYW-26 750 kW CBS

WTXF-42 319 kW Fox

WHYY-55 87 kW PBS

WPVI-64 500 kW ABC

WCAU-67 112 kW NBC


ALLENTOWN


WFMZ-46 12 kW IND

WLVT-62 24 kW PBS


WILKES-BARRE


WVIA-41 (n/a) PBS


HARRISBURG


WITF-36 50 kW PBS


LANCASTER


WGAL-58 (n/a) NBC


I suggest trying the Channel Master model 3023 (also known as the 4248) which is a fringe UHF yagi. Make sure you also order the Channel Master Titan 2 #7775 UHF preamp; it makes a big difference - about 24 dB gain with 3 dB or so noise figure.


You can also try modifying a smaller Channel Master 3022 (4308) antenna. There is a mod posted at www.projectorexpert.com under the article "A Long, Strange Trip". Some people have had quite a bit of success with this modification.


I can watch New York City DTV stations every night over a 65 mile path with either the CM 3022 suburban UHF yagi (with the mod) or the CM 3021 4-bay screen. I use the UHF preamp mentioned on both antennas.


Remember - with DTV, all you need is a carrier-to-noise ratio of about 20 - 22 db to consistently lock up the signal. Conventional analog UHF TV at those signal levels is full of snow.


KC
 

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I posted most of this elsewhere already, but anyway, I am in the north suburbs of Chicago. I get digital stations both from Milwaukee (over 60 miles away) and Madison WI (over 90 miles away) and they lock in perfectly. I am using a $50 Radio Shack antenna (combo VHF and UHF), a $29 Radio Shack signal amplifier and 100 feet of Radio Shack quality RG-6 cable. And I live in a woody area with lots of big trees in the line of sight.


So I don't think you need a monster antenna. I do think the rotator is essential, it would be very difficult to align to the best signal otherwise.


For further information go to www.antennaweb.org
 

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Interesting results from Madison and Milwaukee, Mike. Here in California there are apparently coastal Angelinos picking up San Diego from similar distances. However, the generally accepted horizon limit is ~60 miles. Topographically, California's coast dog-legs inward between L.A. and San Diego. The same appears on maps to happen between Chi-town and Milwaukee (and Madison, too). My suspicion is that in both cases the lucky viewers locking a signal over these distances with more common UHF antennas are enjoying a beneficial boundary lake-effect signal skip. (You're dealing with Lake Michigan, we're dealing with the Pacific ocean.) If my thumbnail analysis is correct, Bromley may still need all the antenna he can lay his hands on to get Philly. He may still be money ahead to get an area expert's advice.


[This message has been edited by Ray H (edited 05-22-2001).]
 

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Thanks Ray: that's good news, I have good open space to the southwest for my DBS signals and just occasionally get rain fade. The only current available local digital station is 35 miles northeast and currently at 40-45 reading on the DTC with pixeling. Thought I'd try a bigger antenna.


Mike: your news from Chicago to Milwaukee is encouraging since I am very near the lake, about 1/4 mile, almost directly across from Milwaukee, in fact with vhf, many times I pick up stations, but snowy. I have more than one roof antenna so some options of experimenting are there, problem is, Milwaukee isn't any further along than Grand Rapids or Kalamazoo with just one lit up so far. Do you know of there plans in the near future? Especially with CBS. I've read ABC is planning much more programming also in the fall.


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hermithill
 

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Hi Bromley,


Every installation is unique. So what works in one installation may not work in another. What works for your neighbor may not work for you. It's a trial and error type exercise for the most part.


Some of the things one need to consider include but not limited to:


* Height of TV Station Transmitting Tower

* Transmitter Power

* Transmitter frequency (TV channel)

* Height of Receiving Antenna

* Terrain Between the Transmitter and receiving antenna

* Obstacles between the transmitter and receiving antenna (tall buildings, water tower, etc.) An attic installation is obstructed.


I always suggest that one always start small and indoor first before going with the bigger and more complicated installation. Again, trying to find the best scenario that works for one's situation is part of the trial and error process.


For more antenna tips as well as recommended antenna for specific applications as well as rotors, etc., please go here .


Thanks,

Errol



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Keohi HDTV

Your Friendly HDTV Tips Site


[This message has been edited by kealii (edited 05-23-2001).]
 

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Ray,


Re the Antennacraft MXU59, this looks interesting, but their web site gives no information at all about gain, directivity, etc. Since you quoted a gain figure, I presume you can tell us where to go for these specs. If so, I'd appreciate your inputs.


Thanks
 

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Quote:
Originally posted by Ray H:
I do wish Antennacraft would list the salient specs on their website for their products.
Ray H, Below is an e-mail that I sent to Antennacraft. No response to date.

Code:
Code:
Subject: Antenna Info
   Date: Tue, 22 May 2001 12:56:31 -0500
   From: "Wendell R. Breland" <[email protected]>
     To: [email protected]

Sir or Madam

Please provide me with Gain, Beamwidth and Front/Back Ratios
information for your MXU59 UHF antenna.
------------------

Wendell

Technical Services Supervisor

MAETV
 

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cymro,


That gain figure was volunteered verbally to me when I ordered. I do wish Antennacraft would list the salient specs on their website for their products. If their antennas are as good as they advertise, the specs would sell more product than their hyperbole does (shades of RatShack). If anyone is interested in personally contacting the person I spoke with, his name is Steve Miller. There's a toll-free phone number listed at the Antennacraft website , under the page heading, "How to Buy".


[This message has been edited by Ray H (edited 05-23-2001).]
 

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OK, Here is the reply to the e-mail sent to Antennacraft. One would think they would have provided more information. IMO, they ought to have Gain, BW & F/B for CH 14 and 59 with several in between. If the 15dB of gain is representative of across the UHF band, that would make this antenna one of the best UHF models.


Subject: RE: Antenna Info

Date: Thu, 24 May 2001 10:35:06 -0500

From: Steve Miller <[email protected]>

To: "'Wendell R. Breland'" <[email protected]>



Please find the following specs for the MXU59.


Gain - 15.1dB

Front to back - 20 median average

Beam width - 28 degrees average half power


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Wendell

Technical Services Supervisor

MAETV


[This message has been edited by Wendell R. Breland (edited 05-24-2001).]
 

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Wendell,


Thanks for posting the Antennacraft MXU-59 information.


Gain is indeed the best, but beamwidth and F/B ratio are far short of the Blake JBX21WB which is 9-11 degrees and 28-30db respectively. The JBX21WB, however, has a lower gain of about 14dbd. I assume that the Anteenacraft gain is also referenced to a half wave dipole i.e. dbd, as I think most antenna specifications are. If, however, the Antennacraft gain specification is in dbi (i.e. referenced to an isotropic radiator), then the Antennacraft gain in dbd (i.e. referenced to a half wave dipole) would be 2.15 db less than the value quoted. Still very good, but not tops.


A feature of the JBX21WB which may be useful is that all the directors are X shaped with horizontal extensions on all corners of the X so that the upper and lower horizontal portions of the directors act in a stacked antenna fashion, presumably reducing the vertical acceptance angle. This may be important in receiving diffracted signals from a ridge between the xmitter and rcvr.
 

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Quote:
Originally posted by cymro:
A feature of the JBX21WB which may be useful is that all the directors are X shaped with horizontal extensions on all corners of the X so that the upper and lower horizontal portions of the directors act in a stacked antenna fashion, presumably reducing the vertical acceptance angle. This may be important in receiving diffracted signals from a ridge between the xmitter and rcvr.
I'm curious - the illustrations of the MXU59 on the Antennacraft web site appear to depict the the directors alternately mounted to the top and bottom of the boom. Would this yield a quasi-stacked antenna effect, too, or am I totally barking up the wrong tree? I'm still waiting on mine - will post results when I finally get it and mount it...

5:30 p.m. PST

Speak of the devil... It just arrived via UPS. Looks like tomorrow will be a busy day! For anyone who can make sense of the design details:


1: Four complete driven elements (i.e. eight half-wave) of increasing length from front-to-rear. (a quasi-log periodic design?)


2: 38 parasitic director elements alternately mounted to the top and bottom of the main boom ahead of the driven elements. These appear to be essentially equally spaced (except where the boom-to-mast brackets and U-bolt attach to the main boom) and all the same width.


3: Six reflective elements each mounted to the corner reflector booms.


4: One additional parasitic element mounted to the main boom just aft of the reflector bracket.


5: And, unfortunately, no listed specifications on the enclosed assembly and mounting direction sheet...



[This message has been edited by Ray H (edited 05-24-2001).]
 

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Quote:
Originally posted by cymro:
Gain is indeed the best, but beamwidth and F/B ratio are far short of the Blake JBX21WB which is 9-11 degrees and 28-30db respectively. The JBX21WB, however, has a lower gain of about 14dbd.
The JBX21WB appears to average about 12dB of gain, the "Acceptance Angle" will be about half that of beamwidth, therefore the beamwidth of the Blake will be about 20°.


Without detailed charts and graphs, some of the above is speculation for both antennas. The Antennacraft is in the $60 range and the Blake is the $150 range, yes???



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Wendell

Technical Services Supervisor

MAETV
 

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Wendell,


The JBX21WB is about $150 including airfreight.


As to gain, I have a graph of gain vs. channel #:


US Ch 14: 12.8db

US Ch 32: 13.8db

US Ch 50: 14.0db

US Ch 69: 14.4db


The average of the above is 13.75db


As to beamwidth, you may be right that acceptance angle = half beamwidth. If this is so, then the JBX21WB beamwidth is 18 to 22 degrees.


I wish antenna manufacturers would be more precise in their terms and definitions.


Ray,


The Antennacraft structure sounds very intriguing. We look forward to your test data.


Thanks for your comments
 
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