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Hi Willen,
What is there to figure out here? The balun can only hook up two different ways. You have a primary and a secondary. Call either end primary then call the other end secondary.
Connect the primary to the FM transmitter and the secondary to the antenna. Try the transmitter out by transmitting something.
Then remove the balun, connect the secondary to the FM transmitter then the primary to the antenna. That's the second way to connect it. If it works better with primary to FM transmitter then keep it that way, or if it works better with secondary connected to FM tranmitter then keep it that way instead.
Do you know the impedance of your transmitter and antenna? Those TV baluns are made for 75 to 300 ohm coupling usually. Since that's a 1 to 4 ratio, if you have a 50 ohm antenna and 200 ohm transmitter it might also work for that.
You could look up the impedance of a dipole antenna, the kind you have, on the web.
There's also a chance you can rewind the balun to match your impedances if 1 to 4 doesnt work, but you'd have to know the impedance of your FM transmitter and of the antenna too.
Hi,
I think the impedance of a 1/2 wave dipole is around 100 ohms, so you'd have to match to that. The 75 to 300 ohm balun would not do that. You'd probably have to make your own balun. Depending on frequency range this might not be hard to do.
Do you only have to transmit at one frequency or a bunch of frequencies?
Why are you using rabbit ears for an antenna? It is directional in two directions and has poor response in two other directions.
Use a whip antenna connected directly to the coax cable and a ground plane. A vertical whip antenna transmits or receives all around.
Hi,
The original balun should have a transformer core that is like a figure 8. You'll be winding around the center leg of that figure 8.
What i hope is that this works for 500mw. That's only 1/2 watt so it should work.
Don't you think the range is also determined by the sensitivity of the FM radio and its antenna? Radios have varying amounts of sensitivity from excellent to very bad. A very bad radio has a range maybe only across a street (30m).Can I transmit more than 5KM using this balun and dipole by 1watt FM Tx in almost open area?
A dipole antenna is directional. It is good in two directions and very poor in two other directions.
Hi Willen,
Apparently there is a problem with the sites you are using. Perhaps try to upload the photos to this forum instead.
I will explain how to build a simple but very
good dipole antenna, and it only took 45
minutes to build.
The antenna rod is made of 6mm copper
tube I found in a shop for cars. It is actually
tubes for the breaks, but the tube works
great as antenna rods.
You can use all kinds of tubes or wire. The
benefit of using a tube, is that it is strong
and the wider tube diameter you use, the
wider frequency range (bandwidth) you will
also get. I have noticed that the transmitter
gives highest output power around
104-108 MHz so I set my transmitter to 106
MHz.
The calculation gave the rod length of 67
cm. So I cut off two rods at 67cm each. I also
found plastic tube to hold the rods and to
give it a more stable construction.
I use one plastic tube as boom and a second
to contain the two rods. You can see how I
used black duct tape to hold the two tubes
together.
Inside the vertical tube are the two rods and
I have connected a coax to the two rods.
The coax is twisted 10 turns around the
horizontal tube to form a balun (rf choke) to
prevent reflections. This is a poor mans
balun and lot of improvement can be done
here.
I placed the antenna on my balcony and
connected it to the transmitter and turned
on power supply. I live in a medium city so I
took my car and drove away to test the
performance. The signal was perfect with
crystal clear stereo audio. There are many
concrete building around my transmitter
which affects the transmitting range.
The transmitter worked up to 5 km distance
when the sight was clear (could not obtain
line-in-sight). In city environment it reached
1-2km, due to heavy concrete.
I find this performance very good for a 1W
amplifier