I'm reasonably well experienced at this point but don't know an awful lot about radio.
Am I correct to assume I can use an amplifier I've built for speaker applications to amplify an FM source through an antenna?
Am I correct to assume I can use an amplifier I've built for speaker applications to amplify an FM source through an antenna?
not at all...
to amplfy an antenna signal, you ll have to build
a dedicated preamp using generaly a single transistor
as active device...
there s scores of such designs on the web...
to amplfy an antenna signal, you ll have to build
a dedicated preamp using generaly a single transistor
as active device...
there s scores of such designs on the web...
Hmm, FM source thru an antenna.
This isn't very clear. If you want to transmit, you can't.
If you want to receive then the easiest thing to use is MMIC, some of which extend down to the FM band. This would be a mini-circuits MAR 6 typically, with gain from DC-2GHz, 22dB @ 100MHz.
w
All depends what signal levels you're talking about, output @ 1db compression is 3dBm @0.5GHz
This isn't very clear. If you want to transmit, you can't.
If you want to receive then the easiest thing to use is MMIC, some of which extend down to the FM band. This would be a mini-circuits MAR 6 typically, with gain from DC-2GHz, 22dB @ 100MHz.
w
All depends what signal levels you're talking about, output @ 1db compression is 3dBm @0.5GHz
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Try minicircuits
Minicircuits makes what is effectively RF operational amplifiers. These are very easy to use and fabricate on perf board and will run on even a poor supply. For the novice just use ceramic disc caps and it will work like a champ!
Minicircuits makes what is effectively RF operational amplifiers. These are very easy to use and fabricate on perf board and will run on even a poor supply. For the novice just use ceramic disc caps and it will work like a champ!
I intend to transmit. I realize I'll need a transmitter to feed an amp.
I have a surplus 1,000 watt RMS general purpose audio amplifier.
My intentions is to use it as a transmission amplifier through a DIY transmission antenna I've designed.
I have a surplus 1,000 watt RMS general purpose audio amplifier.
My intentions is to use it as a transmission amplifier through a DIY transmission antenna I've designed.
sure if I don't bother to change the filters in the preamp stage.
I'm not a beginner, just haven't worked with radio quite yet.
I doubt you'll get any help here. It's illegal for you to transmit without a license other than at extremely limited power levels in specified bands, and they'll probably delete any posts providing direct technical assistance to you.
You may be able to learn how to do this by building or adapting equipment at the component level, but most people find that by the time they have figured out how to do this that they they understand what a goddamned pain-in-the-*** it is to people around and are no longer motivated to break the law in this particular way.
If you beg, borrow or steal the equipment to do it I hope you get caught.
Which is pretty likely since it is a RADIO BROADCAST.
w
...and you're wasting your time with the audio amp.
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Not for FM but for AM it's possible using an audio power amp to drive a modulator. AM uses a fixed carrier whose amplitude is driven by an audio amp, its called AM modulation. Buy a ARRL handbook for diagrams.
FM uses low level audio to vary the frequency of the carrier at a rate equal to the modulation ie the audio.
FM uses low level audio to vary the frequency of the carrier at a rate equal to the modulation ie the audio.
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In the US it IS legal to transmit on the FM band,but with very limited power. IIRC the FCC Part-15 law states 250uV at 3 meters away from the transmitting antenna. In practical terms this equates to something like 11*nano*watts into a half wave dipole.
It's funny though,because there are kits that you can buy which have up to 25milliwatts of output power,and the people using them very rarely ever run into problems with the FCC,etc. (I can only recall one person using such a transmitter getting shutdown,and that was because of profane/political language being broadcast.) Literally hundreds of these small transmitters are in use every day.
The MMIC suggestion is a good one.MMIC's are very easy to use,and you can get up to ~10mw into 50ohms from the common ones. Other than the MMIC chip,all you need is a resistor,and a 2 caps.
They can be a bit fussy because of their extreme bandwidth..They like to oscillate,but careful construction,and perhaps some small bypass caps on the input and output can fix that up.
Look into the Minicircuits MMIC's,they work well,and are easy as pie to implement..the low power level (though technically over the limit) is very unlikely to get you into trouble.
Also, (VHF) RF is nothing like audio. Layout and design is *critical*.
Get/build/buy a low-pass filter for the output,and you should be in good shape.
It's funny though,because there are kits that you can buy which have up to 25milliwatts of output power,and the people using them very rarely ever run into problems with the FCC,etc. (I can only recall one person using such a transmitter getting shutdown,and that was because of profane/political language being broadcast.) Literally hundreds of these small transmitters are in use every day.
The MMIC suggestion is a good one.MMIC's are very easy to use,and you can get up to ~10mw into 50ohms from the common ones. Other than the MMIC chip,all you need is a resistor,and a 2 caps.
They can be a bit fussy because of their extreme bandwidth..They like to oscillate,but careful construction,and perhaps some small bypass caps on the input and output can fix that up.
An audio amp is less than useless at RF,you could modify until the cows come home,but they simply do not have the bandwidth to deal with RF..how many amps do you know of that have a bandwidth from 20Hz-100+MHz? Zero.
Look into the Minicircuits MMIC's,they work well,and are easy as pie to implement..the low power level (though technically over the limit) is very unlikely to get you into trouble.
Also, (VHF) RF is nothing like audio. Layout and design is *critical*.
Get/build/buy a low-pass filter for the output,and you should be in good shape.
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Have to agree there. I have an older Belkin unit sitting on my desk and have also used an earlier version of the iTrip (I think). One thing I like about the device linked to is it can use any frequency in the FM band rather than 3 or 4 like my Belkin. That's not a big problem in my area but can be if you live in an area with lots of stations.I think that you can have a scan to www.fmheroes.com,where you can get a detail knowlege about this.
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