[thebradnet]

A friend of mine has an old TV antenna that they are not using and a light bulb went off in my head and I starting thinking that I could use to for a FM antenna at my vacation home. Currently at my vacation home we are about 30 miles aways from any towns of any decent size. That being said I would like to have a way of getting a better signal without spending a ton of money on all new gear.


I have been doing some research and according to the research I have done this should work. The antenna has twin lead antenna wire connected to it. Problem is my receiver has coaxial style connection on it. To remedy this problem my plan would be to convert the connection from twin lead to coaxial near the antenna and run the coaxial cable about 50 feet to my receiver.


My question is how well does a setup like this work? Is it worth the time and effort?

 

[walbert]

I forget exactly what the "problem" is with this, but it will/should work. There's something about loss or inefficiency that tugs at me when I write that though (something to do with it being tuned for the wrong wavelength, but that may not be it - it's fairly late for me). You need a transformer from 300 ohms to 75 ohms to make the connection. If this is a big external antenna, ensure you ground it properly and all that too.


One other idea, and this may or may not work for you: can you connect your tuner to the cable service at this location? A lot of cable services carry FM along the line, and the signal is usually decent. Would be a lot easier than installing an antenna and all of that.

 

[bbrio]

There is plenty of antenna info on the web, but as I was dinking around recently to get a good FM signal, here are my views.


If you run coax from the antenna base to your house you will need to put the balun (the little transformer going from 300 ohm flat lead to 75 ohm coax) outside (at the junction of the two leads) so it will have to be weatherproof. I read somewhere that there was less signal loss in the old ribbon style flat lead compared to coax which seems astonishing to me. But if the old antenna still has a bunch of flat lead still attached to it, I would try that first, run it all the way in to your receiver. Then you juust need the balun to go into your 75 ohm receiver inputs (and it doesn't have to be weatherproof).

 

[thebradnet]

I will take some pictures of the antenna in just a bit so we can all be on the same page. Right now I have over 100 feet of RG6 cable and the twin lead cable as been cut so I am going to have to use RG6 and but a 300 ohm to 75 ohm transformer outside by the antenna.


Walbert - On the subject of "There's something about loss or inefficiency that tugs at me when I write that though (something to do with it being tuned for the wrong wavelength, but that may not be it - it's fairly late for me)" I was reading earlier about interferice with TV channels and putting a trap on the line. Could that be it?


In a nutshell would I be better of buying a new antenna or would this setup work just as well?


Thanks for the advice!

 

[Gizmologist]

Here ya go.

http://www.tigerdirect.com/applicati...7BBTkwCjCECjCE


Standard TV antennas are highly directional. Many communities have the TV transmitters sharing a tower so rotation of the antenna is not necessary, That may NOT be the case with FM radio transmitters in your area.


Also twin lead (flat 300 ohm wire) needs to be twisted continually along its full length to prevent RF reflections and the wire itself acting as an antenna. Coax lead-in eliminates that.


if penetrating the outside wall for the cable entrance, be sure to use a thru wall entrance tube (Radio Shack carries them) and to leave a 6" drip loop just below the cable entrance and seal with silicone.

 

[cavu]

1. Any elements on the antenna shorter than ~yard are solely intended for higher (non-FM) frequencies and are useless for yor application.


2. Why is this "RF" issue posted in the audio theory section?

 

[dbx123]

Quote:

Originally Posted by cavu 2. Why is this "RF" issue posted in the audio theory section?

Hey, I've seen a few theories put forth here

.



OP, the sensitivity on your AVR's tuner section will play a very important part here. These days (past 2 decades), less emphasis has been placed on a tuner's sensitivity rating, but there are some exceptions out there, as some mfgrs. have realized that FM is still important to a large audience. To go back 25yrs (and I still have this very rcvr), Carver bragged that many of their receivers' would get excellent reception with a mere paper clip unfolded and inserted into the 75 Ohm connection on the back. And my Carver 2000 does get great reception with just that! Anyway, there are many other brands with superior sensitivity, too.


Bottom line (imo); If the 75/300 deal doesn't work well, try running simple speaker wire (in lieu of a flat ribbon type....[which usually work very well when placed/adjusted carefully] if you don't have one handy) and see what happens. The truth is, you can spend a lot of bucks on snake oil cures for poor reception. Antennae have been reinvented a thousand times over the years, but nobody has really ever improved on the very basic principles of what makes the simplest of all work well for almost all applications

. And if you're that remote...it may be that you'll never get adequate reception, no matter what you do and how much you spend. Honestly, 30 miles out of a major city really isn't that far. You should get the "major" stations without too much trouble. Also, keep in mind that sometimes it's the damn radio station's power signal that's at fault (weak), not your tuner!

 

[cavu]

OP: See the following article for basics and dimensions required for FM band ...

http://www.skyscan.ca/Antennas.htm

 

[Ratman]

Test the VHF antenna as best as you can prior to permanent mounting.

Paper clips can work, but not a good recommendation.

Speaker wire can work, but again, not a good recommendation.


As mentioned earlier, 300 Ohm twinlead is good, but can be a PITA to be done correctly (twists and using standoffs).


IMHO, if FM reception is important, buy a new "FM only" antenna and do it right. Less expense and effort than piecemealing an old VHF antenna.

 

[whoaru99]

Quote:

Originally Posted by bbrio I read somewhere that there was less signal loss in the old ribbon style flat lead compared to coax which seems astonishing to me.

As I understand it, that is true, but the added hassle of running the twin-lead ( twisting it, long standoffs, more careful routing around metal objects, etc.) usually sways people to a coaxial install.

 

[amirm]

Two points:


1. Antennas are really cheap. So getting one from someone else is not a big saving

. Be sure it is not rusty and falling apart as some of the old ones can be.


2. Compared to piece of wire people typically use, it should improve your signal reception greatly almost without regard to what type it is. Just hook it up in your living room next to the AVR and you should see the improvement.

 

[bbrio]

Agree with dbx123. I was quite disappointed with my modern AVR's tuner section. Dragged out an old kenwood tuner that I paid 30 bucks for in a secondhand store and I got much better results (Of course I have to plug it into an analog input on the receiver, I am using the "CD/tape" input which is free).


Ditto on the speaker wire. Eventually I ran speaker wire into the house from my home-made folded dipole and somehow that gave better results than the coax and the ribbon lead.


Last thing (nothing but surprises with this antenna business) - I got the best results with the antenna at about 45 degrees from horizontal. Go figure. But experiment with the positioning a bit before deciding on your final location for the antenna.

 

[Ratman]

Quote:

Originally Posted by bbrio Ditto on the speaker wire. Eventually I ran speaker wire into the house from my home-made folded dipole and somehow that gave better results than the coax and the ribbon lead.

Possible explanations:

1) twin-lead not run properly (as explained above).

2) crappy coax (bad connectors/connections).

3) "home-made" antenna that never worked (or constructed) properly

4) speaker wire added and now is an "antenna".


I'll agree with sensitivity between tuners.

Back to the OP:

A 50' run of RG59 or RG6 coax, a 300 to 75 Ohm balun and a new FM antenna should provide adequate results at a reasonable cost.

 

[bbrio]

If your vacation home has an attic and reception proves difficult after trying the usual things, have a look at home-made rhomboid antennas. Apparently they have a nice high gain. They are pretty directional however (but you can combine two of them to improve the situation).

 

[Ratman]

... or just spend ~$30 for an FM antenna and some coax.
http://www.monoprice.com/products/pr...seq=1&format=2


Try one of these. Probably came with your receiver:
http://www.radioshack.com/product/in...ductId=2062691