Distant memory of thrown out RCA console that had AM radio but no FM radio, and phono

[wa2ise]

Almost 40 years ago a neighbor tossed an RCA B&W TV, phono and AM radio console. I stripped out the TV chassis, which also had the AM tuner (two tubes, (6BE6 and 6BA6) attached on the side. The AM detector was some unused section of a tube in the TV circuits, and audio out was the TV audio output circuit. I vaguely remember seeing a record changer in this thing as well. The TV chassis was stripped apart for parts long ago, to build a ham transmitter most likely.

It does seem to be an odd combination in a console, AM without FM radio, phono and of course TV. Vintage style of the cabinet probably from around 1957 or so.

Anyone remember such a console system? Everything in AK always has AM and FM if it has any radio at all, but haven't seem just AM without FM. There was an Emerson portable TV with AM radio, but not a console and without phono.

[Dan Starnes]

In my post of my latest find Philco 1884, it is a combo with AM radio only, in fact playing as I type this. I too thought this was odd, and I have never personally seen a combo without FM. Interesting.
Dan

[electroking]

In Canada at least, until 1960 or so, FM stations were so uncommon that
Eaton's offered only AM in several different models of consoles with phono.
TV with AM only radio is a rare combination indeed as you say.

By the way, in 1974 and in 1982 Chrysler Corp. had a number of car
radio models with 8-track stereo player and AM-only in their catalog.

[electroking]

Hello again,

Here is an excerpt of the Fall-Winter 1960-61 Eaton's catalog(ue) showing
all the consoles available. None included TV. I can post TV sets from
the same catalog if anyone is interested. Regards.

[Celt]

Yeah, AM only wasn't that uncommon. Even remember seeing a AM only solid-state stereo receiver in the early 70's which was around 20W p/ch and had magnetic phono inputs.

[David Roper]

I have two such combos (TV-AM-Ph), an Admiral and a Hallicrafters. Neither has the turntable built in although I'm sure there were models using each of those chassis which did.

[Whirled One]

I remember seeing a TV/AM combo once or twice before... (didn't Emerson make a portable like that in the '60s?) I do remember thinking that was rather weird though-- after all, a TV already has about 95% of an FM radio receiver just as it is-- in fact, adding an AM radio tuner to a TV would probably be more complicated and more expensive than to add an FM radio tuner.

As a matter of fact, I seem to remember seeing in old late-40's-era electronics magazines ads for conversion kits to install a DuMont "Imputuner" in various other-brand TV sets; since the Imputuner had a continuous dial and had coverage of the FM broadcast band, it would have had the side-benefit of turning your regular TV into a TV/FM combo (though of course the TV's video and HV circuitry would still be running when using it as an FM radio...).

[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. I believe every FM/TV combo uses completely
different RF/IF circuits for these two functions, at least after the mid-fifties.

[wa2ise]

Also realize that the FM deviation of broadcast FM radio is much more than that used for the sound on analog TV. About twice or 3 times.

Oh, one could rig up the front end of an FM radio tuner (front end, local osc and RF amp module) to produce 4.5MHz IF instead of the usual 10.7MHz IF. But you could get problems with images of FM stations 9Mhz away.

And also, most manufacturers want to build stuff as large modules. Console TV radio sets were not made in high volume. So the easiest and ultimately cheapest way to build consoles is to use the entire chassis and CRT of the same TV they are making many of, and also use the chassis of AM/FM/phono sets they may also be making, or procure from another maker who does make many of them. Or use say the front ends and IF strips of higher end hot chassis table radios that they are making many of, and tap some B+ and share the audio output stage of the TV chassis, and appropriate switching. But that starts to get to be an engineering effort.

[electroking]

wa2ise, your practical knowledge of radio engineering is truly amazing,
and I'm saying that most sincerely!

[Whirled One]

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.

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.

[electroking]

Originally Posted by Whirled One

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!

...

That's a good point, I have also heard some of those cellular phones on
higher UHF channels. Maybe the interference from some other transmitter
approximately 4.5 MHz away was acting as the LO, but I'm not sure.