On Sat, 28 May 2016 23:26:44 +0000 (UTC),
wrote:

Are such radios sold in the USA via the internet? Is the station really
"fixed"? Someone gave my uncle a radio which is said to have a special
"chip" that receives a Greek radio station. He mentioned to me that years ago
he had another one that suddenly switched to a Philipine station and he gave
it to a Filipino colleague. Amazon and Alibaba have such Metrosonix radios
but not station specific, but also do not seem to allow being sold in the
USA. THe search terms I used were SCA FM radio.
- = -
Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist

Yes, but not quite in the way you describe:
https://en.wikipedia.org/wiki/Subsidiary_communications_authority
In the USA, additional SCA carriers used to be quite common on most FM
stations. They were used to subscription handle background music
(MUZAK), commercial free radio, and all kinds of data broadcasting
(stocks, paging, sports scores, traffic reports, etc).

Most of that died starting in about 2002 with the introduction of
digital FM radio.
https://en.wikipedia.org/wiki/HD_Radio
The IBOC signals occupy the spectrum just outside of the normal FM
stereo signals formerly occupied by SCA sub-carriers. SCA and IBOC
cannot coexist on the same frequency.

In the USA, FM broadcast channel spacing is 200KHz. Stations licenses
in a given geographic area are assigned on alternate 200KHz slots
giving broadcasters a 200KHz guard band to allow for junk receivers
with rather wide IF bandwidth. SCA sub-carriers never went above
about 80Khz, so there was no increase in occupied bandwidth. IBOC
changed all that by grabbing all the spectrum between +/-100kHz and
+/-200KHz:
http://802.11junk.com/jeffl/crud/KCSM.jpg
Such an IBOC transmitter is now transmitting on top of the adjacent
channels frequency. If the adjacent channel is not occupied, no
problem. If there's a station there, big problem.

In some parts of Europe, FM stations are assigned on 100KHz channel
spacing, making both SCA and IBOC an impossibility. I don't know
which countries are like that.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558