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FM WAVE PROPAGATION


prateeksikka
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TV's are doulble insulated a earth pin is only required when an appliance has a metal case.

Higer frequencies do mean more bandwidth,you can't modulate a 10KHz carrier with a 20KHz signal but you could modulate a 20MHz carrier with this 20KHz signal.


prateeksikka,
Yes high frequencies do mean short antennas but the antenna still needs to be on a very tall mast to achieve a long range. If you stand to a mountain you can see from 100s of miles and you can see a mountain from 100s miles away.

I don't mean to have a go but I've already answered your question about high frequencies, did you even bother to read my previous posts?
High frequencies are more prone to interferance and transistors and other components don't work very well at these frequencies, acept in infrared and optical band when LEDs and photo diodes work. - I'm not going to say this again.

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I don't mean to have a go but I've already answered your question about high frequencies, did you even bother to read my previous posts?
High frequencies are more prone to interferance and transistors and other components don't work very well at these frequencies, acept in infrared and optical band when LEDs and photo diodes work. - I'm not going to say this again.


Alun,
You should calm down. You did not need to say that. You are flaming, which is against the agreement to use the forum.
For many members of this forum, English is not their first language. If they do not understand you, they will re-state the question. There is no cause to flame someone for this. In my opinion, the moderator of this forum should have deleted this post. Your sarcastic post would have been deleted in a forum I moderate soon after it appeared.

MP
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Hi Prateek,
He, he. My FM transmitter goes that far? ;D
I am still tweaking my FM transmitter and frequently its output isn't modulated. It must be jamming radio station reception on FM radios with a "blank spot on the dial" all around me.
I've got RF coming out of my wing-wang. It is all over my preamp, 'scope and DMM. Everything I measure has strong RF on it, even me!

I don't know why your AM radio is jammed or broken. I'm not jamming it. I stay away from AM because it sounds lousy.

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hi audioguru!
sorry for it but i could not understand wat u said,i also fear u wrongly
interpreted my question.i meant that the frequency range 88-108 Mhz
for FM and 540-1600 kHz for AM.is not continuous.
i.e all frequencies are not used by am broadcast.some frequencies are used by other applications also
why is it so?
prateek

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hi audioguru!
i must correct u on this point.in my country too ,F,M and AM bands are not used by army,the bands used by them fall into say 540-1600kHz which we vaguely called AM band (atleast in my country)
but thats what i meant by my point earlier,540-1600 kHZ IS NOT F ULLY AM some frequencies are missing and those are used by army .actual AM is say(hypothetical)
540-670
690-880
930-1600
these are assumed and not actual values values falling out of this range used by military


prateek

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hi audioguru!
i had started this topic of FM wave propagation because i had recently built an FM RECIEVER AT MY PLACE ,.it was designed to operate at 220Vac which was followed by transformer,rectifier and filters etc.
actually i had no transformer earlier when i was making it, out of curiosity,i connected only 4V dc (with fear in mind) after the filter directly
and you wont believe,one of my electrolytic capacitors of 470uF
exploded like a bomb! i changed it and put a 1000uF in its place i was shocked when i saw it exploding into pieces,however the circuit worked when i put the T/F in place and connected the mains supply
any comments on how it could happen?
prateek

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Hi Prateek,
Sure, backwards polarity from a high current supply is a good way to blow-up electrolytic capacitors. When I worked on the car-radio production line that's how they tested the anti-reversed-polarity protection diode. They put a heavy bucket over the radio and connected reversed polarity. We cheered each explosion a couple of times per day!
You are lucky your radio's semiconductors weren't destroyed too.

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I KNOW THAT AN ELECTROLYTIC CAPACITOR HAS A POLARITY!
I AM SURE ON THAT POINT !
I CONNECTED IT RIGHT AFTER ALL,I LOST 2 CAPACITORS IN2 HUGE EXPLOSIONS.NEITHER ARISES A QUESTION OF HIGH BIAS BECAUSE I WAS CAREFULLY INCREASING IT WHEN I REACHED JUST 4V IT EXPLODED WITH ALL MATTER COMING OUT OF IT.YMMMMMMMM
CAN THE CAPACITORS BE FAULTY?
PRATEEK

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I dunno.
Reversed polarity is all I can think about that would explode caps with such a low voltage.

I know! AC voltage at a high current explodes them too! Or DC with a high ripple voltage at high frequency.
There is an inverter in our projects section that explodes its coupling capacitors. At first we thought it was because the caps are shown with backwards polarity. Then I realised that the caps have an extremely high AC current that is blowing them. The entire power of the inverter (70W to 100W) is going into those caps.

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