[SOC] FM Receiver - the SOC way.

[Ian C. Purdie]

Quikhooligan wrote:
> On 10/2/2012 6:06 PM, Tom McCulloch wrote:
>>
>>     I'm thinking a building a simple FM broadcast band receiver.
> 
> Why?

Perhaps our intrepid friend Tom has an adventuresome spirit. Perhaps, 
like myself, he might often ask "why is it so" or perhaps, "how does it 
work", perhaps again "can I re-invent the wheel"?

Maybe, also just like me, he never truly grew up and loves to tinker, 
build and, fix things.

A man I can respect and admire.

Answering Tom, the last FM chip I used came from the [memory] ARRL 
Handbook of 1975 which had a 2 metre FM receiver project. At some 
expense I built it that very year. FM radio had yet to be introduced 
into Australia.

That project was built around the RCA CA3075 FM chip. [1970's]. 
Datasheet here
http://www.datasheetarchive.com/CA3075-datasheet.html

National Semiconductor also had AM chips around that time.

Among others, Philips Semiconductor, also developed AM/FM chips.

I doubt if any are still around, if any modern ones are available 
they'll likely be impossible to use because they'll be Surface Mount 
Devices.

Actually in the late 1970's even cheap AM/FM radios I sold were still 
old bog standard transistor types. Open them up and they were all 
identical, irrespective of brand name, from the same Hong Kong factory.

Even the AM receiver component in a high end Sony Sound System I sold 
for $799, had gues wot? The very same frigging board. The FM board was 
more elaborate.

Tom, I don't know what's available today but it surely won't be an easy 
project, even if parts are available. Amateur Radio FM receivers are 
configured for narrow band, about 10Khz while commercial FM is about 100Khz.

I just looked into a couple of CD/DVD players lying around in pieces for 
repair. Alas none have a tuner so I don't know what's used today. My own 
[old by now] Telefunken CD/DVD player/Tuner is most certainly almost 
wholly digital.

Lots of luck Tom.


Thanks! :) 72/73's

Ian C. Purdie
Budgewoi N.S.W. Australia - Co-ords -S33° 13' 54.70", +E151° 33' 4.75"
VK2TIP "I'll give ya the TIP mate" QRP-L #1978. SOC #171 FP#91
http://www.electronics-tutorials.com/