Quote:
Originally Posted by electroking
In an intercarrier TV, an FM audio signal without the video carrier cannot
be received, because the operation of the circuits relies on the video
carrier as a local oscillator to move the FM signal to the audio Intermediate
Frequency of 4.5 MHz.
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Hmm. That's true-- good point. However, oddly enough, from a practical standpoint, it would appear that you don't actually require a video carrier, at least not on most sets. An illustration of this is the fact that it's possible(*) to hear analog celluar phone audio (which is transmitted using FM) on TVs that have coverage of the full channel 14-83 UHF band. There's certainly no video carrier up there!
(*) er, I suppose that should be in the past-tense now, since the analog cellular system is being phased out, so there's probably nothing to pick up these days.
You and wa2ise do bring up a very good point that manufacturers would probably have just used a regular radio chassis anyway, simply because they already have a production line for them and it'd be easier just to connect it up to a regular pre-existing TV chassis.
Incidently, my RCA 8TS30, which has separate sound IFs (not intercarrier), picks up FM radio broadcast stations *really* strongly on channel 1 -- I figure it's picking up a harmonic, since doubling the frequency band used by the old channel 1 would put you right in the FM broadcast band. I've wondered if that's actually one of the reasons why channel 1 was so quickly taken away from TV use.