FM Transmitters

Wayne J

Wayne J

Super Moderator
Staff member
I have a Belkin unit. I done the antenna mod, but was unhappy with the results. It was better, yes, but not what I need. I then removed the attenuation as described in a 'how to'. It got a little bit better, but still is not satisfactory. I think most of my problem is the landscape of my property. My house is down off a steep grade and the eves of my house are the same level as the road. I feel the only solution is a antenna that extends above the roof. I have thought of getting a Ramsey unit, but I am afraid it will suffer the same issue, which is the landscape issue.
I have been using the 'full wavelength' antenna length specs which is 124" @ 94.7. I tried the 'half wavelength which helped nothing.
I am now thinking of extending the audio cable and locating the Belkin outside under the eves of the house and run the antenna up into the air with a small piece of pvc.
Any suggestions??
 
Wayne,
I started out using the Belkin Tunecast II with the antenna mod. It worked. I was able to get a satisfactory signal about 75 feet away with the antenna and Tx mounted outside at a peak height of less than 12 feet above grade. I got decent results but after the Halloween show I wanted more.

I ponied up the dough and bought a Ramsey 25B. Yes you can get decent results with the Belkin but the 2 do not compare. I wish I would have brought the Ramsey to the Mini in NJ, you could have seen it, or in this case listened to it, for yourself. With the Ramsey in the attic using nothing more than the extandable metal whip antenna, like on an older fm radio, I am able to broadcast a quality signal hundreds of feet and can still hear a weak signal upto about 1/2 mile. That is with a height of about 14 feet above grade.

One thing you can not do with the Belkin is extend the antenna and mount it away from the Tx by utilizing coaxial cable, I have tried. This is possible with the Ramsey. So If the problem is the terrain and you need to mount the antenna higher then you would either need to mount the entire Belkin unit up high or get a Ramsey or similar unit. If you mount the Belkin up high you would need to access it from time to time so this might not be feasible in reality.

Just some info to ponder.
 
Zane... I have done all the mods possible to the Belkin and cannot get satisfactory results. It is only decent right in front of the house and has a couple bad spots at that.
I have decided to pick up a Ramsey FM25B kit. I have only heard good things about them and think all of my issues will be resolved.

Thanks for the input guys!

8)
 
GREAT results from Berklin unit

At first I had terible results with the modified Berklin. Then I mounted the transmitter from under the house eveas at the peak of the roof. The antenea wire is dangling downward.
Placed in a freezer bagy to protect from weather. Mounted so high prevents vandelisim as well. Mounted computer speakers next to transmitter, used 1/4" stereo plugs, a headphone adapter from RS (has 2- 1/4" plugs converging into one).
Distance = I was told that it transmitted up to 1/4 mile away but real clear up to 800 feet.
Note- run a power cord to transmitter- using battery power is really not the way to go - no distance and battery use could get to be expensive.
 
The best results I've gotten this far with my Berklin that I got off ebay for 5 bucks in the box was to remove the back cover...I got the Berklin 2 model and it works great with it's back off..I got an extra 50 feet with it.I get a total distance of 300 feet easily with it now and no mods at all other then a transformer.Altho your problem might not be with the transmitter but rather with power lines..Since I do not know your area I had this experence I'd like to share...In my area (which is a home that was built in the 40's and a small bunglo) we all have our power lines in the back of the house.Meaning our power runs over the back yards.For this reason front distance is great back is crap as the power lines interfer with some signals..The higher the frequency the less the noise but the less distance as well.So I choose for a front path and not worry about the back at all.I have mine mounted in my basement with no antenna at all.Simply what it came with and plugged directly into my audio card with the volume adjusted accordingly to get a clear signal that matched the input level on the unit.Other then that it's the best I can offer seeing you might have power lines in the front.I figure no matter what unit you get you will have an issue with dead spots..Another suggestion is to play with a small walkman radio.Try different stations and find which works best in taht area..Then tune your transmitter to taht station and see what happens...If all else fails try the other device..Sorry I can't be of more help then that..
Just a few more suggestions before you spend anyway..
 
I just want to post this so people do not get the wrong idea.

Doug and Wizard are claiming to get some long distances from a Belkin Tunecast II rf transmitter. Wizard says he gets 300 feet of range with no mods and the unit is in a basement. Doug claims 800 feet to 1/4 mile with the usual antenna mod. Now I am not saying these numbers are incorrect or Doug and Wizard are misleading. I want to bring out the point that the numbers these guys are stating are more the exception than the rule. They are not a realistic goal for most. There may be some atmospheric conditions or some structural anomalies that are effecting their installation in a positive way. Most people will average about 100-300 feet max with an antenna mod and the transmitter mounted up high.
 
I fully agree it is unusual Brian..That is why I included my surroundings as well as power line and house type..Simply to give a few people an idea of the experence I've had so far.Now it also stated that since my power lines are in the back the rear portion of the sound from the transmitter is crap.Not very far at all..I got about 50 feet max but out the front I get about 300 feet which for me right now is great.It seems to be this area that works well for it..I have friends with one about 35 minutes away from me and they have the same experence but they used the mods and get a range of about 1/2 mile.Altho they are using a modified and filtered old ham radio antenna with their set up..
 
Your correct on enviroment

I am in the middle of say nowhere!
population - 3000, most live out on ranches several miles from my location.
BUT it would help to mount your antenena as high as feasible and use a power supply instead of battery power.
just the power adapter that came with the tunecast will help.(tap into a 12v lead on your computer.)
 
Antenna Length

Found this info on how to figure the correct antenna length (1/4 wavelength) for your FM Transmitter. Thought it may help someone.

wavelength.gif
 
I just wanted to chime in, my modified Belkin II is marginal at best.
I have a really large corner lot, 1/3 acre, I have lots of curb that i own but the back yard is tiny. My point = 100 foot of range (even with antenna on top of house) is marginal.... it works well within the house, from room to room, but to try to get "full street" coverage, it is terrible.

But on the bright side, I'm going to keep by Belkin as a backup, in case my primary FM transmitter croaks.... (I have no primary FM transmitter yet, still working on that...)

Still looking....


Dave
 
I bought the Ramsey FM25B. I also bought the TM100 antenna. I needed the antenna simple because of the terrain my house sit on. The eves of my house are even with the road, so I needed a way to get the signal up higher than the road. The 25B by itself is great and with the antenna, it is awesome.
 
Wayne J said:
I bought the Ramsey FM25B. I also bought the TM100 antenna. I needed the antenna simple because of the terrain my house sit on. The eves of my house are even with the road, so I needed a way to get the signal up higher than the road. The 25B by itself is great and with the antenna, it is awesome.
Click to expand...

thanks for the tip Wayne...

After about an hour of research i also purchased the FM25B.
Should be here middle of next week.
I am using Anderson power poles connected to the 12V rail of my PC power supply to supply both the transmitter and the cat5e cable with 12V that runs out to my controllers. Should be pretty clean...
Phil's firmware (in non-PWM mode) uses very little current... I think i can run 6 XMUS baords via the CAT5e.... it will either work or it wont :) I'll know soon enough :) (8 xmus boards actually, but 4 will be configured as 8 channels only)

Dave
 
I should clarify, i'm using 3 strands of the cat5e wire for +12V and 3 strands of the cat5e wire for ground....
 
The assembly of the FM25B kit is pretty straight forward, but time consuming. I can take some pics of mine, for some visual aid if you like. The instructions are pic-less. :? :lol:

8)
 
does it really take 4 hours for an "expert" to make it? The directions are pretty long, but it just 400 solder points right? About the same as a xmus board, which takes 70 minutes.... ?
 
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