Power Output Calculation

[torps04]

hi guys, meron po kasi ako project na FM transmitter,
guys pano po b macompute ang power output ng isang FM transmitter, ung mga sinasabing 1 watt or etc.
tapos pano po ito marerelate sa distance na kaya ngang icover?
thanks po

[zer0w1ng]

You need a RF power meter for this.
A ham/VHF 144MHz meter might be useful for this.

A 100MHz oscilloscope (or more) might be also of use.
Just connect a 50ohm dummy load on its output (if the transmitter's impedance is 50ohms also) and measure the voltage.
Then compute the Power as: P = E^2/50, where E is the RMS voltage (Vpkpk/2.828).

Distance is measured using Free-Space Path Loss computation and this is also dependent on receiver's sensitivity, antennas gain, connectors/wire losses on both ends.
http://en.wikipedia.org/wiki/Free-space_path_loss

[maldihtah13]

SWR meter with power meter available sa Raon at around 2K.

If you like may kakilala ako sa lucban na pwede ko mahiram.

I will go to your school sa March 17.

[torps04]

@zerowing
im using a transformer (full wave center tap) 18V 0V 18V,
bali ung E na RMS, alin kya un? ung 18v nb un?
pati pano ko po malalaman kung anong impedance ung ginamit ko?

[zer0w1ng]

@zerowing
im using a transformer (full wave center tap) 18V 0V 18V,
bali ung E na RMS, alin kya un? ung 18v nb un?
pati pano ko po malalaman kung anong impedance ung ginamit ko?

Not on the power supply but on the RF output (antenna port).
Most transmitters have 50 ohms impedance output to be compatible with coaxial cables.

[torps04]

^
ammm. pag mmeasure b ng voltage dpt naka parallel db? hehe.
thx po