Now you can see how poor my English is, I can't figure out how does it look like. Do you mean the resistor paralleled with the coaxial cable? Or touch one end of the resistor to the place to be measured and the other end grounded? Because there're 2 terminal at the coaxial and the scope as well.
Can this be used as a field strength meter? I've seen one, the coil is connected where the 1khm: is. The multimeter should be set in AC mode or DC mode?
I took apart my Field Strength Meter. I forgot it needs a small input capacitor to block mains hum and AM redio stations. Also the 1st resistor is 10k.
Its output is DC or AM modulation.
What is the frequency range of this meter? Only in FM range? Why it doesn't need to be tuned to the right frequency?
What I need to do is just put the meter next to the transmitter and measure right? Otherwise the value I see will be the strong signal from FM station.
Can this meter measure the reception of the receiver? I think no.
My transmitter cannot goes higher or lower frequencies, just around 96MHz. I've tried 99MHz, the quality is a little bit poor compared to 96MHz. Is there anyway lowering or increasing the frequency? When I used the 'scope, it shows a flat line at certain time, I think around 120 degree show waveform.
C6 in my FM transmitter tunes it from below the FM broadcast band maybe down to 85MHz up to about 106MHz. I leave C13 tuned to 98MHz because its tuning is very wide and it covers the whole band.
Here there is a TV channel directly below the FM band. Many FM radios can pickup its audio. You will cause interference to its picture or sound and the interference is illegal.
Above the FM band is the aircraft and air traffic controllers band which you don't want to interfere with. Very illegal.
So is transmitting on FM radio!, depending what country you're in - as you don't have your location filled in we can't comment on the possible legality of it!.
its really a nice thread for FM stuff.i cleared lots of doubts.
thanks guys.
coming in to the topic.i built FM transmitter using transistors.but the quality is not good.so in one thread audioguru said transmitter shld be stereo.i did a search and found two chips.
1.max2606 (later i came to know its not stereo)
2.BA1404 (some one said it produces distortion while working)
but in the below site the creator said that they did lot of experimentation and come up with a good design. **broken link removed**
so i would like to hear comments from audio guru.
can u help me here
thanks
Hi Fever,
Rohm company made the lousy BA1404 FM stereo tramsmitter IC long ago. They discontinued and replaced it about 5 years ago because its performance was lousy. A few kits still have it.