Glad that it is working out a little better for you. The reason that i said to mount it in the window was for specific reasons. If it is mounted in the middle of a window, it is not REAL close to any metal that might detune it plus it is still indoors. This protects the wire from being exposed to the weather and will keep both it and all of the connections from corroding. As mentioned previously, this basic design is omnidirectional, i.e. it should pick up all directions relatively equally as long as the entire antenna is vertical. If you've got aluminum siding, the wooden shudder is near a large metal frame for the window or you have conduit or wiring located closely to the antenna in the wall behind it, this could cause both detuning and directionality. If you can, you might want to run another wire dipole on the west side of your house and then simply hook up an antenna switchbox that you can get from Rat Shack. This would give you the best of both worlds at the flip of a switch. Sean
> |
Well I have tried two of your suggestions. First I moved the T attenna to a different inside wall that faces the direction that I suspect most local signals are coming from and most stations are were received more consistently and clearer.
Sean, I made up the vertical dipole you so completely outlined above. I was able to solder the wires and as an initial trial ran in outside and tacked it behind a wooden shutter on the first floor of our wooden shingle covered home. The stations coming from this side of the house(north) are coming in beautifully, considerably clearer than with the T.
Another local station that I suspect comes from the west is not coming in as well as it did with the T. I am planning to move it higher on a east facing wall to see if that will help. |
Bmpnyc- I am referring to a device about 4-5' long and approx. size of a 2x4. I don't have any significant multipath problems here, I put it in the attic (20' above grade) and I didn't hook up the amplifier, and was pulling in many, many stations without even a good physical connection to my HT receiver (the Yamaha has something that almost looks like a Pal type connector, can't thread the f connector on, but just placed it so the "hot" center lead touched, or even came very close) to the center of the amp connector). Didn't do any critical listening, it was just an experiment on the TV antenna I was going to return. Have no idea how it performs under more difficult conditions. |
I have to agree with Sgmlaw here for the most part. Getting a good outdoor antenna mounted up high with a low loss feedline that is carefully routed is what we should all be striving for. A large Yagi on a rotor would be optimum, but well beyond what most folks require for decent reception. If that's not possible, you may be stuck with one of the indoor antennas or the homebrew that i described. One of the advantages that the design that i mentioned has is that it is vertical rather than horizontal. If you don't think that this makes a difference, take a listen to your car stereo sitting out in front of the house. Chances are, the stock Delco, Ford or Mopar "sound system" with an external body mounted antenna just might be able to pick up stations that your high dollar tuner with great specs and amplified indoor antenna can't seem to pull in. There are two reasons for this. The car antenna and the vertical dipole that i suggest are both omnidirectional whereas many of the amplified antennas and the "T" antennas are cross polarized (both vertical and horizontal) and relatively directional. This means that they are highly susceptible to multi-path and far more sensitive to "aiming". With the vertical dipole, you shouldn't have to fuss with orientation as long as you keep the entire antenna vertical and mount it as i described. If your trying to pick up a specific station but are having a hard time doing it, you can make the vertical dipole somewhat directional by playing with the orientation and direction of the ground (bottom) wire. Another reason that the center fed dipole works well is that the antenna is naturally resonant at the lengths that i mentioned (between 28" and 32"). It therefore offers gain over an "untuned" or "non-resonant" antenna that is of random length or design. One more comment is that sometimes what we attribute to being a poor incoming signal is actually TOO much signal. This can cause front end overload. Signs of this are that the station has a "ragged edge" to it and always sounds like it is not exactly on center channel. While this might sound like the symptoms of a weak or distant station, the difference is that these stations come in quite loud and can be tuned in over a wider frequency range than normal. The signal is so strong that it is actually bleeding over onto adjacent frequencies. This can be caused by being very close to the transmitter or having an amplified antenna system turned up way too much. In some extreme cases, you might even need to install an inline attenuator. This "eats up" some of the signal coming into the tuner, reducing it's strength to a level that the the receiver section can more easily deal with. Keep in mind that if you do have a "mast mounted" amplifier near the antenna, the indoor section of this device MUST be located BEFORE any splitters are put into the system. In other words, you would need to have the outdoor antenna connected to the mast mounted amplifier section, a piece of coax coming down into the house, the control section of the amplifier and then any splitters that were absolutely necessary. Placing a splitter between the mast mounted amp and the control panel could either reduce or absolutely kill the performance of the amplifier, making it useless and sometimes even detrimental to the system. This is often overlooked or not fully understood by inexperienced installers. For those that desire the best performance from their FM systems, you might want to check into the Magnum Dynalabs Signal Sleuth. This acts as both an amplifier and filter and is commonly referred to as a "pre-selector" in the RF field. This makes the signal both stronger and sharper sounding while rejecting outside interference. Hope this helps. Sean >
>
|
An indoor antenna may or may not help you in this situation. Unlike AM, antenna mounting height will make a large difference both in FM sensitivity and multipath rejection. Another factor to consider is whether you need a directional array to capture these stations. Before investing in any antenna, I would suggest making some walkaround reception observations with a high quality portable monaural FM radio in your listening room. These units, being mono, generally surpass all but the finest stereo units for sensitivity and selectivity. I have used the GE Superadio II for this purpose with very good results. This should give you an initial indication of whether reception is possible for this location, the 'hot spots' in the room for best reception, and what directionality, if any is needed. Don't be upset if you find that you simply cannot get good reception - occasionally an interior room will simply not permit satisfactory reception. My own listening room has very poor FM reception and I am forced to go outdoors. If you are lucky enough to obtain decent interior reception, try to stay with a passive antenna. Believe it or not, the humble 300 ohm "T" is one of the best. Sean's homemade design is very good also. While some have had success, I am not a big fan of the $100 designer interior antenna, and think even less of the Radio Hack models - many having built in amplification that simply mangles any signal. Don't forget to take the "T" right up to the ceiling, the higher, the better. If you cannot obtain a satisfactory signal from the "T", you probably won't get it with any other interior unit and may have no choice but to go higher and perhaps outdoors (if you simply cannot leave the room, then your only possible option is a better tuner, which in virtually all cases represents very poor value per dollar over a better antenna). While this may not require a roof mounted array, you might first consider an attic-mounted or exterior wall mounted omnidirectional unit. The Fanfare omni is quite good - and so is the $20 Radio Hack "X" model. If you have a drop ceiling, you can sometimes fit the "X" above it, with varying results. But these units perform best outdoors. Remember that ANY quality outdoor antenna, properly mounted, will outperform any interior model, period. If you have a multipath issue or require maximum gain, then you may be forced into a directional unit, which may require roof or obstruction free mounting. Radio Hack outdoor antennas are OK, but not great value, IMHO. The better, sensibly priced, outdoor models can be found from Channel Master and Winegard. A couple of other pointers if you're serious about this: First, unless you are prepared to buy the very best (i.e. Blonder-Tongue, Channel Master, etc.), avoid all RF amplification - most do a horrific job and impose unacceptably high levels of noise. A quality, low-noise FM amplifier can run upwards of $200. Unless you really live on the fringe, most folks simply don't need them, and the money spent on amplification is better spent on a larger or better passive outdoor array. Second, if you have a lead in run under 20 feet, you may use 300 ohm twin lead (this has the lowest loss, but is generally unshielded and will pick up noise). Ideally, shielded 300 ohm cable is the very best for this application, but is nearly impossible to find anymore. If you have a longer run, the shielding of 75 ohm coaxial outweighs it's higher loss rate. Remember too to use only RG-6 coax, as RG-59 has a very high loss rate. The good thing about basic radio reception (raw sensitivity and selectivity, not all those other qualities we associate with high end tuners) is that the antenna is 90% of the deal - an average tuner with a great antenna will run rings around the very best tuner with a poor antenna. The latter part of this response admittedly exceeds your question, but may be of some help should you decide to attempt a more complex installation. |
Sean,
Wow. Thanks for taking the time to respond. I printed out your directions and will read them in detail. I'll let you know how it works if I go that way. Will also consider the Terk. Thanks to all for the responses |
Swampwalker,
I might be mistaken, but I had a "stick" from Radio Shack, and it was rather lousy. The Terk is very good. Of course we may be thinking of two different antennae, but I don't think so. |
Thanks for the conformation, Sw. You know us neurotics. I actually put the antenna up because I was tired of the 6bucks going to Direct Tv./for the local channels ea. mo. I did buy their (RS) amplified 29 or 39 job= not nearly as good as the 19/outside one. I bought my present fm tuner from Nanderson/ I figure him to be an fm god.I was embarrassed to ask him about a tv antenna/for FM. |
Av- nothing wrong at all, FM and TV same basic signal, just different frequencies (I think FM lies between two of the VHF channels). FYI, I think that Radio Shack has an amplified stick that appears to be the same as the Terk FM-Pro for a bit less $ (80-90). Works great here in Hartford, CT |
My Terk FM-Pro works great, and in NYC that says a lot.
Costs around $100-150, and can be hidden quite well despite its size. (about 4' long and 5" wide). Hats off to Sean for taking so much time to respond in great detail. |
I just put a splitter on my line from the over the air tv antenna.From where I live the tv & fm stations are all 40 or so air miles east of me.I use the button that cuts off any noise between stations I get 30 or so clear as a bell stations. Am I doing something wrong I don't know about? The antenna is one of those Radio Shack 19.95 jobs. |
Very nicely done Sean. I think I may pull out my old Marantz modle twenty just to try it out. Thanks for the great post, J.D. |
PS........ Sorry for the novel and some of the wording errors. I hope you got the idea. Sean
> |
Here is a simple approach that works quite well in many installations. It is a "quick and dirty" vertical center fed dipole antenna that should easily outperform the "T" antenna that your using or even one of those fancy $80 antennas from Fanfare or Magnum. I will give you the basics and you can improvise from there. You will need a section of coax to reach from the point of installation, a 60" piece of wire and some clear 2" packing tape. I would recommend using a LONG length of pre-packaged coax so that you can cut it to length as needed once your done. If you can solder, that would be great, otherwise simple wire wrapping will suffice as long as you make a secure connection. First of all, you need to locate a window that you don't mind leaving closed that faces the direction of the majority of broadcasts that your trying to receive. In other words, a window that faces the nearby City in most cases. Once you've done that, you will need to construct the antenna. You can use either insulated or uninsulated wire, either will work. Start off by cutting two 30" sections of wire. You will need to also strip the end of the coax that your going to use and seperate the center ( hot ) wire from the braid ( ground ). You will need about 1" of exposed wire from each of these, but you have to make sure that the hot wire is still insulated from the braid. If you can solder, attach the center wire to one 30" section at the very end and the braid to the other 30" section of wire at it's very end. Do this as neatly and as sturdily as is possible. If you can't solder, simply twist the wires as mentioned above as best possible without breaking them. You can apply a small amount of tape to hold them together and reinforce them, but DON'T count on the tape to make the connection. Now take the entire length of coax and the wire to the point of installation, the window facing the broadcast center. What we are trying to do here is to situate the antenna as high as is possible while still keeping it away from any metal framing that the window or sill might have. In other words, DON'T mount it off to the side or all the way up against the metal framing if at all possible. Running it down the center of the glass in an open area will give best results. Take the wire that is connected to the center section of the coax ( this is the "hot" wire ) and tape it near the very top of the window running vertically. This means that the "free" end of the wire is near the ceiling with the "connected" draping down towards the floor. Once you have the very tip of the vertical antenna reasonably secured, come down it's length and tape just above the connection to the coax. Keep in mind that you want to keep this straight and pulled reasonably tight. Once this is done, take a small piece of tape from the dispenser and place it nearby. Now you need to secure the bottom section of the antenna, commonly referred to as the "ground plane". This should be strung vertically down the window in the same fashion as the "hot" wire was done so that it looks like a straight line. Make sure that the "hot" wire and the "ground plane" are still isolated from each other but don't try to pull them too hard to keep them seperated. Your connections might pull apart and we don't want that. Now secure the "ground plane" just under the coaxial split with that small piece of tape that you previously set aside. Like you did with the top section, stretch the "ground plane" towards the floor as straight as is possible and secure that section at the tip. Once you are satisfied with the basic installation, run a piece of tape vertically on top of the wire the entire length if at all possible. If part of the ground extends below the bottom of the window and down the wall, that is okay. It is best if it is not right by a power outlet though as that means that there is conduit nearby and it might affect the tuning of the antenna. Once this section of the installation is done, it is up to you to route the coax to the tuner. Obviously taking the shortest path is best but as a matter of convenience and practicality, that might not be possible. You might want to try the antenna out BEFORE doing any type of permanent installation, as it would be a bummer to go through all of this without it giving you the performance that you were looking for. Once your sure that it is working to your satisfaction, route the coax as best possible, cut it to length leaving a bit of slack and then install a new "F" connector. This should do the job for you without having to go on the roof for anything. This basic design gives good omnidirectional coverage but could be affected by all of the conduit or aluminum siding on the house if you have it. This could also be installed outside by securing it to the outside of the building or a nearby tree. Don't run the wires vertically along a metal pipe or mast, as that will drastically alter its performance. Should the connection ever break and you need to shorten the antenna section for some reason, the overall length is not real critical. You would want to stay with something between appr. 28" and 32" for both sections though. Having them exactly the same lengths is not necessary, but they should be close. The shorter length of 28" will favor stations higher on the dial while the longer length of 32" wil favor stations lower on the band. If you listen to specific stations on one extreme or the other, you might want to take this into consideration when doing the initial install. Hope this helps someone out. Should you have problems or questions, hit me with an email. Sean
> |
First try taping the t to a t shaped stick and then moving it around until you find the best spot for most stations. If that's not satisfactory, try a rabbit ears or other indoor TV antenna and do the same. If that doesn't work, there are amplified antennas that can be mounted inside. I assumme that you are using the supplied transformer/adaptor between the 300 ohm T and the 75 ohm F connector on the receiver. |
