In article , "Richard"
writes:

Although I have been interested an amateur radio for about 30 years, I've
never focused much attention on radios made with ICs.

Lately I have got an interest in FM receivers, and have discovered some
FM-related IC's/chipsets. ICs such as LA1177, LA1266, LM7000, (these three
being a chipset), and LA1235 etc etc.

But, doing a web search , you cannot find any homebrew AM/FM RX using these
IC's.

Why is this? I would have though they would be ideal for the hobbyist to
mess around with.

Yes, you CAN find the parts...those that survive after the 20 to 30 year
period from their new introduction until now. The MC3362 is a one-chip
FM receiver package available from Kits and Parts. Just add the dual
IF filters and support passives, perhaps a power audio IC for more
sound, maybe an RF stage for maximum sensitivity. Dieter has a
datasheet available for download on it if you like.

Problem is that few of those old ICs survive. They didn't sell well enough
to support continued production. Hundreds of IC designs have met that
fate, were successful, were produced, were sold. They just didn't sell
enough. A few were sold off to other semi makers (Fairchild got all of
the old National Semi digital line, for example...ON Semi got some of
the old Motorola ICs). About three "independent" semi makers in the
USA exist as second sources for old, obsolete semiconductors,
including specialty ICs. The old RCA Sommerville works and their
mighty CMOS line of both digital (CDxxxx) and analog (CAxxxx) got
partially picked up by Harris when RCA was sold to GE, but then
Harris sold off most of those to others, including Intersil and a few to
Maxim (according to part numbers and description).

What you, me, and many other hobbyists have to face is that the
scene in semiconductor ICs is CHANGING. There exist (and have
existed for at least a decade) "foundry" services to allow designs of
complex ICs that may be the entirety of a new electronic project.
Those won't even appear on the distributor market, just single
purchase lot of 100,000 or so, made, installed, and in a successful
product only to be succeeded by a changed, more competitive
device.

You CAN find out much with the right search words, including old
part numbers. Unfortunately, many of those old parts have become
"unobtainium" and exist only in archival datasheet records. A few
remain: MC3362, a one-chip FM receiver; SA602 and SA612 Gilbert
cell RF mixers; MC1350 low-VHF differential amplifier; several LMxxx
audio devices from National; MC145151 parallel-load PLL all-in-one;
CD4046 phase-freq detector for PLLs; 555 timers. The venerable
741 op-amp has long since been replaced by several general purpose
op-amps still produced by several makers. Many CDxxxx CMOS
digital devices are still available at very low prices (Jameco) and a
few CAxxxx analog CMOS are still there.

Outside of the Heathkits at the last decade of their existance, I
doubt you will find much in the way of articles and "plans" for a
homebuilt AM/FM receiver. When the already-manufactured article
costs less than the collection of parts needed to build one, why
bother? :-) If you want to build a special version for yourself, there's
a heaping glob of appnotes and datasheets for available components
on the web...but then you have to DESIGN something (true homebrew)
instead of copying someone else's design.

Len Anderson
retired (from regular hours) electronic engineer person