I want to build a narow band fm receiver capable of receving 140-160 MHZ?

Question

I would like to build a radio receiver capable of receiving around 140-160 mhz in NFM. I want to be able to get a clear signal to feed to my computer sound card, and also posibbly to a ADC later on. I want to be able to record in at least 96khz audio, if not higher. I have some basic knoledge of electronics, and was wondering if anyone knows how dificult this will be, and what parts and schematics i will need to have in order to build it.

And i want it to be digitaly controled with a channel step of 5khz

Answer 1

You would probably be better just buying a cheap radio or scanner which will also give you access to other channels, frequencies as well as giving you stable and verifiable frequencies. You could pick one up cheap in any secondhand shop usually.

However, if you want to build one from components it's possible, but it is better if you can get a kit with a premade PCB.

You would then probably be better looking for an IC solution rather than discrete. I have given a sample data sheet for the Motorola MC3362 which includes PCB layouts.

Just put 'semiconductor data sheet fm radio vhf' in your search engine and you'll get lots of references.

The only other thing I'm curious about is why you would want to record NFM at more than 96kb (I presume you mean the MP3 rate which is kbps (kilo bits per second not kHz)? NFM is really designed to be used for voice and to allow a lot of channels in a narrow frequency band. Increasing the recording quality above 96kbps will not gain anything as the original quality won't be there in the first place. Similarly, using a specialist ADC solution won't gain anything over a soundcard solution.

Good luck and have fun.

JUST SEEN WHAT YOU'VE ADDED
So, if you want a cheap solution to a computer controlled NFM radio, instead of building the radio, why not build the interface to a prebought scanner. You could parallel tha keyboards switches with CMOS switches such as the CD4066 which has 4 in one IC. These could be controlled by a parallel port card or a I/O card which can be bought as kits as well as fully made and then programmed to sequence the switches as appropriate.

Answer 2

U probably do need a superhetoredyne receiver,to do this u must first came out with the block diagram of how a super....receiver is form then u can then include ur Band pass filters and dephasers where necessary.If u need real clearity u can go for ic's that will replace the fundamental capacitors and resistors in ur filter ckts , voltage generators and control feedback loops.
U will need components like regulators,opamps for stages A,B,C ,mixers,vcr's,ect

Answer 3

U need a superhetrodine receiver. The stability of your oscillator is very critical. When I first started in the air force comm ,The transceivers that went up in the airplanes due to temperates that in a short time the ground stations and the aircraft were on different freq. till they couldn't talk to each other.

Answer 4

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