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help me

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motwani.jayesh

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i have stereo fm transmitter using BA1404 i want transmitter to transmit at 70 MHz to80 MHz please help me what to do i dont know about LC ratio whether its L/C or C/L ratio you can send me private messages i stay in INDIA
 

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MikeMl

Well-Known Member
Most Helpful Member
Change the LC ratio of L1 and the 10pF capacitor across it. Read the note in the referenced paper about frequency stability.

Bad idea in the US; first it is illegal to operate a license-free transmitter in the TV band. Second, your signal would be totally clobbered by the high-powered TV transmission at the frequency you specified.
 

Chippie

Member
Change the LC ratio of L1 and the 10pF Second, your signal would be totally clobbered by the high-powered TV transmission at the frequency you specified.
Mike, fine choice of words..I think the technical term is 'swamped'....:)





PS...where are the smileys for that matter? I found them ;)
 
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Hero999

Banned
He didn't fill his location in.

70MHz to 80MHz is not the TV band here in the UK. I could be wrong but if I remember correctly some baby monitors and cordless phones use 80MHz perfectly legitimately.
 
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audioguru

Well-Known Member
Most Helpful Member
I think 70MHz to 80MHz is part of the FM broadcast band in Japan.

The lousy old BA1404 FM stereo transmitter IC had very poor performance so it was discontinued and replaced by a new family of excellent ICs that use a crystal controlled frequency synthesizer with phase-locked-loop about 7 years ago.

The website in India also shows the new circuit with the BH1417 IC.
 
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