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There are the Winegard single channel VHF antennas. Actually I dont think that they make the signle channel ones anymore - instead you can buy a broadband Yagi style antenna that works on channels 2-6 or one that works only on channels 7-13. I use one of the 6 element hi-band (7-13) flavors to pick up NBC on channel 11 in San Jose, they're DTV feed being on 12-1 and 12-2. It works quite nice, and is relatively compact compared to a full-blown VHF monster.
 

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Discussion Starter · #3 ·
My problem is that I need a small antenna because I live in an apartment. I am trying to find one that I can fit out on my balcony without being to intrusive. What is the model # of the small one you have glgorman?
 

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 http://www.starkelectronic.com/wya6713.htm


I've got the YA-6713, which I am quite happy with. It has the 75 ohm output. The CC-3613 variety appears to be the 300 ohm kind, and Stark now has that one listed "No longer can get".
 

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What VHF channels are you trying to receive, how far way, and are they in the same general direction?


Among small yagi style antennas, the UHF elements do not add appreciably to the size or the cost of manufacture, which is why most of them have been discontinued. Channel Master used to have the model 3606, which I used to use in cheap attic installations. Wineguard used to make PR-5000 as its smallest VHF-only antenna, but, as I recall, both that model and the PR-7000, which has comparable VHF elements, is about a foot narrower at the dipole and reflector, giving them relatively weak performance on channels 2 and 3 (virtually no gain over dipole), if that is important to you. These antennas are about 100" wide.


If you need any channels in the 2-6 range, you will either have to have a very wide antenna, or settle for the performance of a gizmo antenna, like a Channel Master Stealth. All well designed antennas that receive VHF lowband channels are about 9 feet wide. A Wineguard PR-7005, which is a VHF-UHF combo antenna, is nine feet wide, but only 40" long, as the UHF section adds virtually nothing to the size of a small combo antenna. If you need a little better performance on channels 2 and 3, a PR-7010 antenna gets you 2 dB more of gain on channel 2, but is about 66" long (by 110" wide).
 

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Discussion Starter · #7 ·
I need to get in channel 2. I think I could handle something wide on my balcony, it is the length that would be difficult to deal with. I live approx. 16 miles from the transmitting tower and all the towers are in the same direction. I was able to pick up channel 2 a couple times with no problem with my amplified indoor antenna, so I thought there was hope of getting it consistently with something a little larger.
 

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I looked at what I think are your market listings at http://100kwatts.tmi.net/tv/CLE.html and found that sure enough there is a digital station WKYC-DT assigned to channel 2! Most of us here are concerned with picking up UHF stations. Even in the case where there are VHF locals, those are usually analog and thus fall into one of the categories: get on dish, get on cable, get with coat-hanger, or dont care.


We get our analog locals for the San Francisco area via DirecTV, and thus I only need the Winegard to get 12-1 out of San Jose. It works quite well. I am however in a rather weak signal area, except for some nearby things like a couple of big cell towers and or local sherrifs' 911 call center. Some of these things put some rather large spikes in various places on my spectrum analyzer display. Its also the sort of thing that will overload preamps or even totally freak out an STB.


Thus, I have a couple of antennas that feed modest gain preamps, like only 10db, which are followed aggressively by FM traps, band separators, etc - before being combined and reamplified and sent on to better places (such as my TV). Well, yes then - before I put in all of that filtering - the high band Winegard did pick up some junk from channels 2,3,4,5, and 6; even though none of those stations are in the direction that the antenna is pointed. This pretty much being the coat-hanger principle: any hunk of metal will act as an antenna at most frequencies.


But as I think about it, you probably would get just as good of a result with a StealthTenna or some such thing, at least on channel 2 that is, as compared to force-fitting an antenna designed for another band. There is however something that you might look into if nothing seems to work, that being any of the ham radio literature for 6-meter antennas. You would be most interested I would think in something like a "compact yagi for six meters". Ham radio antennas for some of the longer wavelengths (like 40 meters) that use resonator coils to shorten the elements are quite common.


The six meter ham band being from 50-54 Mhz, while channel 2 is 54-60 Mhz. Its pretty close and you can likely retune or scale an existing design. For a really cheap design for a shortened dipole, you take twice the normal length of wire - meaning a full wavelenth of wire (6 meters ~ 20 feet), and make a coil wrapped on an insulating rod. Feed it from the center just like a normal dipole - without a 300 ohm transformer. Put a few turns in the coax right before it connects to the antenna, coiled up a few inches in diameter and tied with tie wraps, thats your balun.


You can probably squish the main coil length down to about 3 or 4 feet over all - somewhat under half the size of a full dipole at channel two, without seriously affecting performance. It should compare favorably to a reqular dipole if you fiddle with it.
 

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Discussion Starter · #10 ·
glgorman,

I would like to try your idea of making my own shortened dipole. I need 20 ft of wire, but what type copper or steel? Does it matter? Make a coil? Does this mean wrapping it on thickness of the wire at a time all the way up the insulating pole? Does insulating pole mean that it cannot conduct electricity, eg. wood? I don't know what a normal dipole looks like, could you give a description. And how do I connect it to the stb and antenna? Do I use a 75 ohm adapter? Sorry for my ignorance I have no experience in this, I am a pharmacist. But I wish I was an engineer at this point.
 

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16 miles from the transmitter a simple length of wire would, in most cases be adequate, unless you have a mountain between you and the transmitter
 

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Quote:
Originally posted by Jeffrey Schlak
glgorman,

I would like to try your idea of making my own shortened dipole. I need 20 ft of wire, but what type copper or steel? Does it matter? Make a coil? Does this mean wrapping it on thickness of the wire at a time all the way up the insulating pole? Does insulating pole mean that it cannot conduct electricity, eg. wood? I don't know what a normal dipole looks like, could you give a description. And how do I connect it to the stb and antenna? Do I use a 75 ohm adapter? Sorry for my ignorance I have no experience in this, I am a pharmacist. But I wish I was an engineer at this point.
I did a search on Yahoo for "helical CB antenna", since these are very similar to the kind of antenna that I am describing. Here is a link to one brand that shows a picture of a typical mobile antenna. Note that this one is made to work on 27 Mhz, so it would be twice as big as you want. But you can at least take a look for the general idea.

http://www.wilsonantenna.com/fg.htm



Now as for building yours?


Regular copper wire should work fine. Stranded wire has lower loss at radio frequencies than solid wire - but it wouldnt make a lot of difference either way. Its easier to get solid wire to stay put I suppose when you wind the coil, but you can always use tie wraps to keep it in place. Size isnt too important, as long is it isnt too thin, like phone wire. So you'll probably do fine with a cheap roll of insulated number 12 to number 18 general purpose hookup wire, single conductor.


Wood works fine as an insulating pole until it gets wet and soaks up water, then it becomes quite lossy. So you will probably want to to start out by testing the design with a broom stick handle or some such thing, and if you like it - build a permanant one using a fiberglass rod or else using some varnish/sealer on a solid wodden dowel.


As far as the winding pattern goes, you are on your own. Usually the windings are spaced kinda far apart near the feed point of the antenna and then they scrunch up more near the middle and then you have a straight stub of wire near the end. Commercial units for CB and the like come in all kinds. You'll have to experiment.


As far as connecting it to your STB goes, you will want to take a regular run of 75 ohm RG-6 long enough to go from your box to where the antenna is and use that to connect to the antenna. Naturally I already own all of the needed crimpers and such to deal with such things, maybe I take this for granted? I would therefore suggest that you install your coax run from the STB to where the antenna is going to go - with standard F connectors on both ends. The connector at the antenna end (on your balcony?) would then be attached to a grounding block. The typical grounding blocks that are in common use are just double male F connectors attached to a bracket. So you will be able to properly ground the thing if you so desire and have a place to connect the potential mess that will conjure up next.


If you have the right strippers and crimpers and the like, this part will be very easy. If not, it can be VERY frustrating to have to redo the feedline where it attaches to the antenna and end up with a wire that keeps getting shorter and shorter until you are back at square one. So here goes:


Take a piece of coax with an F connector at one end and strip back the other end to obtain a few inches of the separated ground braid and center wire. Coil up a couple of feet of coax into a coil a few inches in diameter near the bare ends and tie that coil permanantly with tie wraps. Now take your 20 feet of regular hookup wire that you bought in your favorite color and cut it into two pieces each 10 feet long. Wrap those peices on your insulated rod starting from the middle to each end. Dont wrap the turns too close togther at first, then bunch them a bit as you move toward the ends, then finally leave at least a few inches of straight wire at the very end.


Your stripped back leads from your coax connect to the wire ends at the middle of the antenna. You dont use a 75-300 ohm transformer here, you just have to make the connection, either by soldering or using crimp connectors or the like. You might want to use round crimp type spade terminal on both the antenna leads and the coax ends, then join the spade leads together with screws and nuts, with soldering its just to easy to melt the coax inner insulator and then you have a mess. Try to mount the thing so that the coax comes away from the antenna at a 90 degree angle, i.e., so that the coax feeder isnt running parallel to and right up against the pole.


Another really GOOD method for making the connection is to buy a chassis mount F connector just like the kind that you have on the back of your STB/TV/VCR etc. They're really cheap even at RatShack. I made a very cheap antenna for my brother this way. We scrounged a chassis connector from an old, old cable box and found a metal bracket that went to some old curtain rods, or maybe it was window blinds that had been replaced. Well, the cheap (free) metal bracket just so happened to have a hole that the chassis connector fit into perfectly, thus allowing us to solder a length of wire to the center pin of the bracket as one lead of the antenna. The bracket itself was then bolted to an old lamp stand on a tripod from a defunct shop light, which itself was sufficient to act as a ground plane. The whole thing then went on the roof -- and it worked - uh, well according to which ever way the wind blew (literally) .. but that was a 5 inch piece of wire cut for mid UHF band, and it was like Christmas or something, and raining, etc ... and it worked long enough for him to feel guilty and go out and buy a real antenna.
 

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If you go to any amateur radio store you will find copies of the Antenna handbook put out by the ARRL. This or the Radio Amateurs Handbook will give you all of the information you need to properly calculate the element lengths and then connect them to your system. The trickiest part is that amateur antennas are normally designed for 50 ohm impedance feedlines and TV uses 75 ohm. You can use a standard balun that goes from 300 ohm to 75 ohm that is available at radio shack. As suggested earlier if you are going to build your own antenna for channel 2, you can take a 6 meter design and just shorten it slightly although it is most likely close enough to work as it is.


..Doyle
 
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