portable FM transmitters to relay an Fm station over a hill

[Ozman]

Hey Engineers, I have a good question:
when I am up in the NEK VT I love listening to a radio station From ME called 105 TOS. the one problem I have tho is I cannot get it over the hill and instead I get cool 105. the place I live at is almost on top of a hill where I could get this station. all I need is about 1/4 to 1/2 a mile range to relay the signal on a dead frequency and boy there is a lot of them. I was just going to use a battery operated Walkman for the tuner a 1/8th and cable to a portable transmitter. the problem I have is I don't know where to get a Portable battery operated transmitter that would have the range of about stadiums length. do you guys have any suggestions for me? the easy answer would be listen to the station online But 1. there is no cell service where I am for tethering, 2. there is no high speed internet so we only have dial-up copper wire at 26K. and 3. TOS does not have an online radio stream. What would suggest for me? feel free to e-mail a suggestion too here or at t-h-e-o-z-n-o at G-m-a-i-l dot com
thank you.

 

[Field_strength]

Try Ramsey Electronics. http://www.ramseyelectronics.com/hk/default.asp?page=amfm

 

[ChiefEngineer]

An old process used years ago not written much about involves placing FM antennas frequency dependent in such a location. One receive, one transmit, unpowered.

Theory is the same as that of the old flyswatter dishes on 6 Ghz. 10 foot transmit dish aimed "up", flyswatter on tower aimed 20 miles to next flyswatter. Receive dish aimed up at that flyswatter.

Anyone have experience with this process used on cable years ago? Two tuned antennas with even a bandpass filter.

 

[kenglish]

A half mile might be a stretch, unless you use some big antennas at both ends (the transmitter on the hill, and your receiver down the hill).
Also, you'd need to get some kind of power...maybe a set of solar cells and a bank of batteries. Are there enough potential listeners to make it worth building a translator station permanently? Sounds like you have two stations on the same channel, so a booster is out.

 

[Fieldtech1]

Theory is the same as that of the old flyswatter dishes on 6 Ghz. 10 foot transmit dish aimed "up", flyswatter on tower aimed 20 miles to next flyswatter. Receive dish aimed up at that flyswatter.

Anyone have experience with this process used on cable years ago? Two tuned antennas with even a bandpass filter.

I remember reading an article online years ago about a town in a remote valley ,in I think California, doing something like this to get internet to their library, town hall, ect. They basically shot a 5.4 ghz signal from one side of the mountain where they could access a T1 to some type of passive RF reflector on the peak that sent the signal down into the valley on the other side.

 

[Fieldtech1]

Hey Engineers, I have a good question:
when I am up in the NEK VT I love listening to a radio station From ME called 105 TOS. What would suggest for me? thank you.

My solution....
Using a radio that picks up the desired station with headphone or RCA out into this with the appropiate cable......
http://cgi.ebay.com/1-2g-3000mW-Wir...121?pt=LH_DefaultDomain_0&hash=item3cb16bb6b9

Ive used an almost identical unit and it was reliable for clear audio to about a half a mile with near line of sight. Also this unit has Mono audio.

Then the receiver portion of that AV linker into a stereo or even an Ipod transmitter to here the station around your house on any FM radio.

Bear in mind that the end picking up said station from top of hill will require a power source which can either be a 12v AGM Deep Cell Battery which will need a solar panel to stay charged, or AC adapter if mains power is available. Also the unit operates on 1.2ghz which is prob illegal in US but since you are in a remote area I doubt anyone will notice any interference.

 

[Play Freebird]

An old process used years ago not written much about involves placing FM antennas frequency dependent in such a location. One receive, one transmit, unpowered.

Theory is the same as that of the old flyswatter dishes on 6 Ghz. 10 foot transmit dish aimed "up", flyswatter on tower aimed 20 miles to next flyswatter. Receive dish aimed up at that flyswatter.

Anyone have experience with this process used on cable years ago? Two tuned antennas with even a bandpass filter.

To determine if this is practical, calculate the path losses of each hop (taking antenna gain into account), add them together, and then you'll know how much signal will be present at the receiver. Unless the primary station has a clear line-of-sight path to the repeat point and the second hop is very short, a passive repeater will not perform well.

You can plug the numbers into this calculator:

http://www.rac.ca/tca/Received Signals.html

For example, let's suppose the passive repeater site is 65 km (40 miles) from WTOS, across a perfectly clear path (no obstacles penetrating the first Fresnel zone, which is unlikely at that distance.) WTOS transmits 57 kW on 105.1, but the path loss across that distance is around 109 dB. Let's figure the receive antenna is a large yagi with 12 dBi of gain, and the cable to the retransmitting antenna has 0.5 dB of loss. Even so, the power at the input of the second antenna would be only about -20 dBm or .00001 watt.

Then, we'll assume the second path is 1.6 km (one mile) with 12 dBi antennas at both ends and a cable loss of 0.5 dB at the receiver. If unobstructed, the second hop would add nearly 77 dB of path loss, but with those large yagis at both ends the calculator shows the received signal at around 47 microvolts. With a good tuner, this would provide only marginal stereo reception.

In the real world, it's unlikely that you'll find perfectly clear paths, so once you take the obstacle losses into account, you'll probably find that you need amplification at the repeater site, i.e. a translator.

If you're in the Northeast Kingdom of VT, I can tell you right now that a passive repeater isn't going to work.

 

[Ozman]

Thank you guys so much for all the feedback. I am going to look into the wireless reciever more.
If you have any ideas as well for portable transmitters let me know

 

[nd2023]

You could try an amplified antenna on the side of the hill facing the station, attach about 100 feet of coax to it, and an unamplified rabbit ears antenna on the other end. That'll boost the station's signal on the same frequency, although you'll still have co-channel interference. It's perfectly legal since you're not broadcasting anything yourself.

 

[Play Freebird]

You could try an amplified antenna on the side of the hill facing the station, attach about 100 feet of coax to it, and an unamplified rabbit ears antenna on the other end. That'll boost the station's signal on the same frequency, although you'll still have co-channel interference. It's perfectly legal since you're not broadcasting anything yourself.

Go ahead and give it a try, but I think you'll find the amplified antenna's gain is insufficient to make much of a difference past 100 feet or so.

One of the items in my shop (found at a hamfest last year for 10 bucks) is a Radiometer SMG1 Stereo Generator, an older piece of test equipment made in Denmark which was designed to align receivers -- but as a mini-transmitter, it sounds quite good. It has an internal FM modulator that outputs 100 mV, about 20 dB more than needed for good stereo reception. When connected to a unity gain antenna, I can hear the signal maybe 500 feet away on a portable, but beyond that distance the path loss is just too high for good reception.

I'm not sure how much money you want to spend on this WTOS quest, but you would probably get better results from an unlicensed 2.4 or 5.8 GHz link from the receive site back to your house. Or else, move to Maine!

BTW, I did some freelance work at WTOS over 20 years ago; it was interesting to visit the transmitter shack atop Sugarloaf Mtn and see the remains of busted antennas at the base of the tower.