Tuner lovers and radio experts, I need your help!

Yashu

I live in Houston TX, and I own a Sansui TU-417. The tuner is in good condition, however, the reason I even own a tuner is one college radio station called 91.7 KTRU and a couple other public stations lower on the dial.

I have one of those whip antennas and it sucks... I can only mount stuff in-doors, so here is my plea:

I heard that you can make your own antenna that is tuned to a favorite station. I have looked all over the net and all the instructions are extremely complicated and seem written by electrical and radio engineers for electrical and radio engineers.

So... if anyone here actually knows how to do this, and can explain to me in lay terms how to do it, I would greatly appreciate it. Right now with the whip, I get a weak signal, and some crackling, popping, strange whiny noises, and so on. On good stations, I get some strange artifacts, where it sounds like the audio is being smeared over time... I assume this is because I live in the city. Anyway, I am interested in making an antenna that will do it's absolute best on the low end of the dial. 88.7-91.7 is all I am interested in.

I know a little about electrical work, I can solder, I know the basic terms and components, but most of all, I can follow clear instructions... so if anyone has expertise that they can lend me to help me pull in these stations I would truly appreciate it.

I have tried to ask this of the people on AudioAsylum and was basically laughed out of the room. They do not like radio newbies, they refuse to explain things in a way that a non radio technician can understand, and of course, they bash the fact that I bought a whip antenna in the first place, or tell me that I need to mount some giant thing on the roof, which I can't do since I live on the first floor in an apartment. This must be an in-doors antenna.

I am hoping there is someone here that can help me through the steps to making an antenna tuned for those frequencies. There must be someone that is still into radio... hehe... Houston has 4 wonderful public stations in that range and I would really love to enjoy them.

bikezappa

http://www.fmtunerinfo.com/

Scoll down to the antenna section.

You have a nice tuner.

Have a blast

[Deleted User]

Hello,
Good radio reception has always been something that I enjoy. I can understand your desire to have an antenna specifically tuned to the radio station you're interested in, but it might not be the best answer, in your case. You mention a smearing effect to the sound and that you live in a city. In all likelihood you are probably hearing multi-path distortion, caused by the FM radio station's signal becoming reflected by nearby buildings, etc. Once an FM signal is reflected and then received a fraction of a second later this smearing sound can result. In order to solve this problem you'll need a high gain, highly directional antenna mounted so it can be turned 360 degrees. The antenna will have a number of reflecting elements that increase the strength of the signal to the main dipole section of the antenna. It will also need to have very good side rejection qualities. The goal is to have a very directional antenna that is very insensitive to signals coming from directions other than the desired one.
I can recommend Channel Master's better antennas as well as the Grundig antennas (Matthew has this brand, I believe) and look at the specifications for gain and rejection. Then mount, as high as possible, and have a rotor and controller to allow small rotation adjustments. Think of the antenna as a directional microphone, able to be pin-pointed to the desired source and very directional. If you still want to build your own antenna I believe Audio Amateur had some articles several years ago. Perhaps they would have them on their web site.
Regards, Ken

bikezappa

Kenneth Swauger wrote: »

Hello,
Good radio reception has always been something that I enjoy. I can understand your desire to have an antenna specifically tuned to the radio station you're interested in, but it might not be the best answer, in your case. You mention a smearing effect to the sound and that you live in a city. In all likelihood you are probably hearing multi-path distortion, caused by the FM radio station's signal becoming reflected by nearby buildings, etc. Once an FM signal is reflected and then received a fraction of a second later this smearing sound can result. In order to solve this problem you'll need a high gain, highly directional antenna mounted so it can be turned 360 degrees. The antenna will have a number of reflecting elements that increase the strength of the signal to the main dipole section of the antenna. It will also need to have very good side rejection qualities. The goal is to have a very directional antenna that is very insensitive to signals coming from directions other than the desired one.
I can recommend Channel Master's better antennas as well as the Grundig antennas (Matthew has this brand, I believe) and look at the specifications for gain and rejection. Then mount, as high as possible, and have a rotor and controller to allow small rotation adjustments. Think of the antenna as a directional microphone, able to be pin-pointed to the desired source and very directional. If you still want to build your own antenna I believe Audio Amateur had some articles several years ago. Perhaps they would have them on their web site.
Regards, Ken

I agree but he is limited to indoor only. You migth try RH rabbit ears for $10. You can adjust the length to match the frequency of the station you want to get. You can get an extention cable between the tuner and rabbit and move the antenna everywhere in the house. The key is to experimnet with positioning with the rabbit ears.

Yashu

bikezappa: Been to that link, does not have anything with clear instructions on how to do this, I will look again though, maybe I missed something. I feel like, there must be a way, it is so frustrating to be able to only listen to my favorite stations in the car. I assume this is because the car is moving through any "cold" zones quickly and so the freq. of driving through these spots increases as you move faster so the sound seems clear once you are moving at more than a few mph.

Kenneth Swauger: I appreciate the reply, yes I think a directional antenna would work, but it still needs to be in-doors... even if I have to rotate the thing myself, it would be no big deal since I only listen to a couple stations. The one with the multipath distortion is 88.7, and 91.7 doesn't have it as bad, but the signal is much weaker and so there is much more hiss and crackle. I wouldn't mind any solution that would be small enough to fit in-doors. I suppose I will check those antenna brands, and also look for those instructions. I know I have seen some for using a wire loop on tubing, with foil covering half, but it all uses language that makes it extremely ambiguous as to how to actually "tune" it.

hale2thechief

Yashu, I never took you for a Rice Radio man.

I can't vouch for the design, but I found this yesterday: http://www.wryr.org/Antenna_instructions.pdf

It looks deathly simple, just make an "X" out of dowel rods and wrap your wire around the perimeter. The trick, of course, is in the size. If it doesn't work, I owe you $3 for materials.

[Deleted User]

Of course, I should have noted the apartment mention in his message.
Ken

Yashu

You can adjust the length to match the frequency of the station you want to get.

That is my problem. How do I figure out the proper length. There is so much information, but for radio technicians, not a novice like me. How does one calculate the proper length for a certain station? Isn't it something like half of the wavelength... or something? Not sure. If I wanted to pick up 91.7mhz, what length is the best to use?

Yashu

hale2thechief: When it comes to radio, I listen to only 91.7, 88.7, 90.9, and 90.1. I love all these stations, but 91.7 and 88.7 the most. I cannot listen to commercial radio... the compression, the "formats", the commercials... it's just awful.

I would love to have 88.7 with no multipath, and 91.7 with a strong signal... I have put my antenna everywhere and still get hiss and crackle on that one. I bought the analog tuner because every digital one I tried would drop out in stereo mode to mono, or just mute completely. I can get 88.7 with little to no multipath using a T antenna, but then I can't get the others at all.

Yashu

Alright, I printed out the PDf instructions. I am going to try it if I can figure out a proper size. I have plenty of wire, and I can get dowels at the hardware store. The only other thing I can think of is this: http://www.antennaperformance.com/products2.asp?ProductID=46&CategoryID=1

Looks like it's going to be a heck of a weekend. New Preamp coming on friday, going to see SAW IV saturday, and have an antenna to build.

hale2thechief

In the past, I've put a splitter on the TV cable and run one line to my receiver. Not all cable companies have FM cable, but you might find the additional wire gets you higher on the building. Just a thought.

Polkersince85

I believe 39 in length is optimal for FM. Try two lengths of wire 39 in. long mounted along the ceiling with lead wires (300ohm) to the tuner. Play around with the direction. This will give you an idea as to what pretty much any commercial non-amplified antenna will do.

Yashu

That PDF is impossible to figure out exactly what the result is supposed to look like. I wish there was an actual picture, and not just a diagram. It looks like it is supposed to be a simple square loop, or one square loop and another loop that is in the shape of a square minus the smaller square and then both connected together... the instructions don't make it clear either. Sigh. I will try google image search, maybe someone has a picture of what it actually looks like. Have you built the design H2TC?



Can't tell if he means one large square with the leads connected on the left, going around in a loop, or two loops, one smaller square on the bottom right, and another loop going to the right, then around, then to the middle left, around the smaller square and back down the middle for the other lead.

Yashu

I believe 39 in length is optimal for FM

Is there a length more specific to the lower end of the dial. I am assuming that it would be longer? I am shooting for 88-92mhz.

edit: nevermind about the link I posted, it didn't help, it had a formula that I would never be able to calculate, all I could gather is that the standard T half-wave dipole antenna is tuned to about the middle of the FM band. I am not sure how to get the right length for 88-92mhz.

[Deleted User]

Hello,
I believe, if my calculations are correct, the wavelength of 91.7 is 3.28 meters or 10.75 feet. So, a section of 300 Ohm twin lead that is 10.75 feet long is "tuned" to that station. Now you can see why antennas are "quarter-wave" designs that are tuned for the middle of the radio band. Granted the signal strength is reduced, but who can deal with a 11 foot antenna? A quarter wavelength of 2.69 feet should give good results. If you adjusted the two arms of the "rabbit ear" antenna to that dimension it should work.
As always, have fun!

bikezappa

http://ham-radio.com/k6sti/

Look for the Titled Dipole.

The problem is that you may not be able to get a clean signal into room the tuner is in. I suggest that you relocate the tuner or antenna (which ever is easier) in a new location and check to see if there is an improvement. If there is get a long interconnect for the antenna in the better location.

Yashu

So, a section of 300 Ohm twin lead that is 10.75 feet long is "tuned" to that station.

So would this be a loop of 10.75 feet wide, as in, the straight (top) part of the T, or is this the "unfolded" length, where a loop, would end up being hald that width?

If I am reading you correctly, that 10.75ft length is for the width of the top part of the T dipole antenna, which would be something I could actually build, if I needed to, but if my memory serves, the T that I have, that I got at radio shack, must be a half wave, because it is probably 4-5 ft across, unless I am wrong on my definitions there.

bikezappa

I don't think the length of the dipole should be 10.75 feet.

Yashu

That is why I think he meant total length, where the folded dipole would be half that, but not sure.

[Deleted User]

Hello,
You would be using 300 Ohm twin lead wire that is 10.75 feet long. Think of this as the top of a regular "T" shaped antenna. Take only one of conductors and find the middle point and cut through the plastic and the wire. Use some diagonal cutters to strip off some of the insulation on these two wire ends. Then take another length of 300 Ohm long enough to reach your tuner and strip off the insulation on both ends. One end connect to the exposed wires of the "T" and the other end connect to the 300 Ohm terminals of the tuner. If it doesn't have 300 Ohm terminals you'll need a 300/75 Ohm balun transformer. All of this should only be a few dollars and I hope it works well for you.
Ken

Yashu

Thanks for the info. Kenneth, I am going to try that, I do know how to make one and I do actually have a balun, and now that the 10.75ft length is confirmed as the total length of the top of the T, I have a wall that is going to get experiented with, mwahahaha.

Does cutting the length directly in half create a "half wave"? or is there something else to half wave and quarter wave than simple math?

[Deleted User]

Good luck on your project!
I believe the math is just that simple.

bikezappa

I'm confused Yashu. What is a whip antenna? For auto? If so that is not good. I thought that, the whip, was your dipole antenna. They sell the dipole at the RS for $4 all soldered up. It is about 5" long I think and is for FM only. A better antenna is the $10 rabbit ears with adjustable length and positioning, Tilted Dipole. Your problem maybe the whip antenna. In any case you will need a long lead wire from the antenna to the tuner to find the best position for the antenna.

Keep it simple first.

bikezappa

http://www.northcountryradio.com/Articles/fmdip.htm

Here is the simple instructions for making your own dipole for a single FM station.

It's about 5' long.

[Deleted User]

Hello,
Just to show the level of entertainment possible on this Forum, here's how to determine the wavelength of an FM radio station with a carrier frequency of 91.7mHz. This can be fun at parties. We need the speed of light in feet per second. So 186,000 miles per second multiplied by 5,280 feet per mile gives
982,080,000 feet per second (pretty fast, eh?, just a shade under a billion feet/sec). If we divide this by 91,700,000 cycles per second you end up with 10.0709 feet. This is the wavelength.
Ken

Yashu

I kindof had a feeling it was going to be something like that. That wasn't the complicated stuff I was talking about in my first post, to see what I was talking about there, just check out that link that Bikezappa provided earlier, http://ham-radio.com/k6sti/, and just take a gander at those lovely coordinate graphs and other metrics of radio antenna performance. THAT is the stuff I truly do not understand, anyway... I appreciate the breakdown Kennith, and I feel like an idiot now since I am kindof an amateur astronomer, *laughs and hides*.

But also, on AudioAsylum, they are ALWAYS talking about a home made antenna that involves a coil of wire around a cylinder with some conductor foil on one side for directionality... that is the one I was talking about in my first post that I did not understand how to do. I did not know that the dipole was even that good, but I guess it isn't so bad. I did know from personal experience that the whip omni antenna is crap.

By whip I mean literally a magnum dynalab antenna I got a while back that everyone said was so great, it is an omni, not a dipole, now that I remember, and yes it sucks. The dipole I have is about 5ft, yes, and is of the radio shack type variety. I have had mixed success with that one, better with one station but saturating others (I feel like some of the distortion is pure saturation aside from multipath, because I do live in the city, but not in the middle of downtown, as in, not as many tall buildings). I thought about mounting it to a wooden frame so I could move it around. I have also tried rabbit ears, but from what I understand, the dipole has more gain, unless I remove the lead on the ears and solder a bunch of stuff to them before soldering the coax back on. I tried to plug them right into the tuner via the balun, and it sortof worked, but I could not move them much since the cord is short. I do have a ton of coax that I use for the whip, but I have not tried it with the unmodified ears yet. I wonder if that would make a difference.

By looking at that website it gives a rough geometry that I can use as a starting point, even though I don't understand the graph measures, I certainly do understand the geometry.

The 10 foot dipole sounds like it would be neat to try just for kicks, and even if the half wave that I have is "close", I can use the 10.0709 to really get it spot on (making my own), as a half wave, so I can mount it to a frame for moving around the room.

The square antenna thing, the guy really needs to work on his writing and presentation. There really is no way to tell what the design is supposed to look like. I read and work with structural drawings all day and I still can't tell if it supposed to be one big loop or two smaller ones, one being 1/4 the area of the other.

ESavinon

I've had very good results with this antenna in nyc.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=210-210

Yashu

Hmm... I actually have a Terk that is similar to that one. It is tall instead of square. Results never could get my digital NAD tuner to stop dropping out of stereo on some stations, it worked ok for the analog tuner though. The best results I have had so far are thus: for 91.7, the dipole with a signal amplifier, but with that setup, it totally saturates 88.7, and makes that station unlistenable. For 88.7, the best results have been the dipole without the amplifier, but then other stations drop out.

The omni has been better for all around, and I can move it about easier, so that is what I have been using. I think I am going to make a tuned half wave dipole, and mount it to a wooden frame, that way I can move it around like I can the whip, but I will try unmodified rabbit ears first, and see how that goes. I will have to use a male to male adapter AND the balun, but I will be able to use my 50ft coax to move it about the room.

bikezappa

Yashu wrote: »

I think I am going to make a tuned half wave dipole, and mount it to a wooden frame, that way I can move it around like I can the whip, but I will try unmodified rabbit ears first, and see how that goes. I will have to use a male to male adapter AND the balun, but I will be able to use my 50ft coax to move it about the room.

Let us know if that works.

The higher the better. Can you locate rabbit ears outside of a window?

Just to see if it helps improve the signal.

Jed Leland

Hello,
Very informative thread, sirs! I learned me a thing or two.
Jed

Yashu

Can you locate rabbit ears outside of a window?

This would be a maybe. Might look weird to passer-bys, but worth a try. Right now, I have the tuner disconnected for some rearrangement. I got my new pre yesterday and am in love, so had to move the tuner out of the room for the moment. I am not sure how I am going to fit everything. I will probably take the old amp and stick it off to the side and use the NAD link to control it, so I can keep the tuner in it's place. That is the ultimate plan. I am going to try to mount a half wave in my front window. A true audiophile arranges his/her room around the stereo, but the tuner has no remote, so I my foot needs to serve as the remote, so it needs to be at least nearby.

The first link there is the dipole that I already have... it works fairly well, but it depends on there I mount it as to which station I pick up the most clear. I will get back to you when I get something hooked up to let you guys know how it went.