HFU HF Underground
Technical Topics => The RF Workbench => Topic started by: ThaDood on August 26, 2022, 1750 UTC
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https://www.radioworld.com/columns-and-views/guest-commentaries/turn-off-the-stereo-and-see-what-happens
FM mono??? This tells you how tech has changed over the years. 30-some years ago, if you wanted FM mono, you reached over to a switch and flicked-off the STEREO mode. Today, since most, if not all, FM analog tuners, made today just don´t have that option. So, they have to suggest that at the transmitter end? Uh-huh... Don´t you see the irony here? Damn... I still remember the excitement when Panaxis, then Ramsey FM-10, TX´s, featured FM stereo at the milliwatt level. Even Part #15 FM TX´s, that broadcast less than 100ft TX, in FM stereo. What would be a better article is to tell folks, whom want a MONO feature on an FM radio, is to tell them how to install a switch to GND-out the 19kHz pilot carrier. Instant mono, problem solved...
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Interesting. With digital quality (whatever that is..) everywhere, no-one knows much about the analogue world, except perhaps for a few vinyl enthusiasts. I recently restored a Fisher receiver, and had to learn about how the FM stereo circuitry operated, to understand what was really going on in the alignment of the MPX decoder, and its correct operation. This being mid 60's equipment (of quality), the selector allowed for Mono, MPX permanently active and an automatic mode driven by a detector for the 19kHz pilot. Nicely implemented, and very effective in practice.
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All of the early Walkman's had an FM stereo/mono switch. My main in house Technics receiver, late 70's model, most certainly had the stereo/mono option by just turning a knob. A lot of FM stations that carried some non-music programming didn't use the stereo generator when transmitting that stuff, if you had expensive balanced speakers, listening to the broadcast through them was a low-fi waste when the station was tx'ing in mono. You switched your receiver over to mono, to get full sound.
BTW, all quality receivers and amps had tubes, solid state stuff sounded like crap. You had to make sure you turned them off or you could fry your tubes. I knew guys who had to drive home at morning break because they left them on in the hurry to get out the door to get to work.
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My Yamaha & Pioneer receivers have stereo/mono. I do like having that option.
My Part 15 xmtr came with a stereo chip, but I replaced it with a mono chip to eek out a slight increase of distance. I usually listen to it on a tube FM receiver, which is mono anyway, or I'm mowing the lawn listening and with the mower noise, stereo isn't all that important. But, at the edge of the property, stereo vs mono does make somewhat of a difference (granted, while mowing that's only 10-15 minutes anyway).
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Now that I've thought about it, I had people telling me to turn off the stereo quite a bit when I was younger. ;)
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https://www.radioworld.com/columns-and-views/readers-forum/your-feedback-on-fm-stereo-vs-fm-mono
Huh... Well, I didn´t think that this was going to be such a big issue. I still say, have STEREO / MONO switching done at the receiver end, and let the listener decide.