Combine 100W FM Transmitter and 300W FM Transmitter

DickCappels

Joined Aug 21, 2008
7,979
Is your FM station licensed to operate?

I would point out that difficulties would be involved. The instantaneous phase of the signals from both transmitters would have to be the same when combined to feed the antenna. Might not even be possible with the dead carriers. Add modulation to the separate transmitters (mono or worse stereo) and you have a nearly impossible mess on your hands.
 

Thread Starter

JusofCariaga

Joined Aug 17, 2021
6
Yes, sir, Our FM Radio Station has been licensed to operate.

By the way sir, I will consider your brilliant advice sir. Have a nice day sir.
 

LowQCab

Joined Nov 6, 2012
1,339
Antenna,
Antenna,
Antenna Gain / Directional-Properties,
Lower Coax Losses,
Antenna / Coax / Transmitter / Impedance-Matching,
Antenna-Mast / Tower- Height above ground,
Antenna,
Antenna,
Antenna,
Antenna, ....................

Oh, and did I mention ANTENNA ?

With the right Antenna set-up,
You can easily cover an entire small Town with ~1-Watt of RF-Power.
.
.
.
 

Juhahoo

Joined Jun 3, 2019
250
If you have a licensed transmitter tower and you ask such a question "how to boost my coverage with two transmitters", this would end your license very quickly.
 

LowQCab

Joined Nov 6, 2012
1,339
When the antenna went from 4 to1, this will greatly change the effective power. Receivers will see your station as 1/4 the power.
Or less
the Tuning / Impedance / Structural-Integrity of the Antenna could be
damaged to the point of becoming a really bad "Dummy-Load",
with drastically reduced Gain.

.
.
.
 

sagor

Joined Mar 10, 2019
512
Fix the antenna first. Putting an extra 100W into a poor antenna will not help coverage much at all. Fixing the antenna, and improving it will make the biggest difference.
Adding 100W to a 300W transmitter will only make a small difference in coverage. Even improving your feedline to antenna would make a bigger difference (depending on length of cable).
 

Ioannis66

Joined Nov 7, 2012
44
If as I understand the problem is the money, just sell the 100W transmitter and with the money fix the Antenna.
As mentioned earlier, antenna and cable make the BIG difference in your covering area.

Once with just a few mW, not even a Watt, I covered my medium sized town! How? With a very good and high placed antenna.
 

MisterBill2

Joined Jan 23, 2018
9,814
First, the antenna is the most critical part of the system, and so repairing the antenna, or replacing it with another one of a more efficient design, is the first choice, and really your only choice. If you do not need an equal signal in all directions, then an antenna design that focuses the signal in one direction can be a real benefit.

There is no simple and effective way to combine two signals of similar frequencies effectively.
The mechanism to do it will cost more than a new transmitter, if you can even locate a source of it.

Repairing the existing antenna is the way to go, and at those power levels the hardware should not be a big problem. You will need to adjust the repaired antenna for the best match to the transmitter. This will require somebody with some technical skill, and that may be a big problem.
 
As a former broadcast engineer, I read this thread with great interest. But there is one question that was never asked. Are you trying to broadcast two separate signals, on two different frequencies? Then, yes, you can purchase a commercially built combiner.

But, if as most here assumed, you are trying to boost power, you have more problems than trying to combine and phase match two separate transmitter's.

First, the FCC, wouldn't like it. There would be way too much spurious emissions. So, I have to agree with most of the answers here. Fix the antennas. Possibly even the transmission coax cable. AND make sure the whole setup is impedance matched through a tuning network.

This will save you many headaches, money, and your license.
 

MisterBill2

Joined Jan 23, 2018
9,814
I had made the rash assumption that the two transmitters were assigned the same frequency. And then presumed that the TS wanted to sum the powers. And since the transmitters are FM, rather broadband commercial broadcast. Then in post#4 it is stated that it is a 4 element circular dipole array, with three elements damaged. No clue about how damaged, though.
I get the impression that the station was ordered from a catalog and the pieces assembled and the technical knowledge was at the seller's end.I know such deals are available. Ready ti connect and play, radio broadcast stations for those technical skills are limited to plug and play.
 
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