Scored on eBay. Looks like a Motorola engineer built it to show off the C-Quam system and demonstrate how an existing receiver could be modified to add an AM Stereo decoder. The radio they chose is a TRF design famous for its DXing capability.
-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
Motorola C-Quam AM Stereo custom built promo radio
- Thread starter kevtronics
- Start date
Back in the '90s, I built a wideband C-QUAM receiver when I was Engineering Director for 1010AM, Tampa.
The receiver took a feed from the studio RF amplifier which also fed the modulation monitor.
The audio output sounded great but I had to add a 10kHz notch filter to kill the adjacent channel "whistle" during nighttime operation.
The receiver took a feed from the studio RF amplifier which also fed the modulation monitor.
The audio output sounded great but I had to add a 10kHz notch filter to kill the adjacent channel "whistle" during nighttime operation.
You absolutely scored big here!
How so? So he can listen to AM stereo stations playing music that don't exist?You absolutely scored big here!
I think I saw a buggy whip on EBay recently. That would be an equal score!
I have my own. There are low-power Part 15 (-ish) AM Stereo transmitters you can buy or make yourself, or you can use the sample output of a C-Quam exciter:
Great. Wouldn't a set of earbuds and your phone be more convenient?
Not when you're a Millennial luddite like me and only use a flip phone.
Wonder if Greg Buchwald, who is Mr CQuam of Motorola, did that...I'll have to ask him
Plenty of AMs running stereo playing music.. WYLD AM 940 in New Orleans is 10kw day and though it's religious format,its in stereo and has listeners who love it..AM stereo is richer than FM stereo IMPO..most people don't miss audio above 10k..not much energy there to make a difference. Just because you obviously don't like it doesn't mean it doesn't work or isn't on air...How so? So he can listen to AM stereo stations playing music that don't exist?
I think I saw a buggy whip on EBay recently. That would be an equal score!
Are the majority of their listeners listening in AM stereo? Of course not. They're little ol' ladies who don't know what AM stereo is.
Assuming anything else is just silliness.
Most AM rolls off well below 10kHz. If you can't hear frequencies above 5kHz, you seriously need a hearing checkup.
That's more silliness. AM stereo never got started, and has been over for decades. To suggest anything other that enough radio nerds that can be counted on one hand actually care? Borders on delusional.
I thought about leaving a very long reply and then I thought you know what it's just not worth it. It's obvious that you're very stuck on yourself and your ideas. I don't have time to argue with somebody like you. I put my money where my mouth was and I bought a radio station and it ran, will run again CQuam stereo. What have you done?
As it relates to AM stereo? Well, let's see.. Back in the day, I've installed one Magnavox AM stereo system, five Motorola systems, and one Kahn system. I removed the Magnavox after about six months once testing was completed, and four of the five Motorola systems after it was determined they were more of a hindrance than a benefit. The Kahn system later became a Powerside, but it also proved to be a PITA than it was worth and was removed when I became chief of the station.
I also worked with Bob Carver when he was developing his AM stereo FM tuner. Bob determined that whole project was waste of easily a year of effort and R&D, because nobody was interested in AM stereo, and for various reasons, it performed too poorly. Much of that was because program directors insisted on asymmetrical modulation, which created unacceptable levels of IM, and the interfacing of the exciter to a transmitter not designed for it, reduced measured performance on a case-by-case basis. In other words, AM stereo lacked consistency station by station.
Feel free to wax-on nostalgically about how AM is just fine and AM stereo could rise like a phoenix. I've heard it for years from the handful of radio nerds that seem to be stuck in some strange 70's time warp. Anything positive about the future of AM, and certainly failed AM stereo, is noting more than tilting at windmills.
Besides, this thread should be in broadcast history, because AM stereo is a teeny tiny footnote in radio history.
Last edited:
There was an LG flip phone I had for nearly a decade, and to my amusement (at the time), it had a fast 3G internet, a camera (meh on quality), downloadable games including SimCity, and at the time, emojis were just beginning to roll out. It did not, in fact, have earbuds. Of course, it's amazing what I can do with my touch-screen phone today, but I will always miss the flip phone. At least, this phone has a headphone Jack, since the newer phones are taking it away again.
Sort of related:
I bought a new Sony SRF-A100 (multi system AM stereo radio in late 1984), although WHB and WDAF (and KSIS and WLS) were all broadcasting AM stereo, my particular Sony radio never had a stereo effect from these stations regardless of the switch setting (FM stereo worked fine, it wasn't an amp/speaker problem).
Anyone with this model of radio have this problem?
(a few years later I bought a Radio Shack [C-QUAM] AM stereo "component" home radio and Sony SRF-42 AM/FM stereo radio)
Kirk Bayne
I bought a new Sony SRF-A100 (multi system AM stereo radio in late 1984), although WHB and WDAF (and KSIS and WLS) were all broadcasting AM stereo, my particular Sony radio never had a stereo effect from these stations regardless of the switch setting (FM stereo worked fine, it wasn't an amp/speaker problem).
Anyone with this model of radio have this problem?
(a few years later I bought a Radio Shack [C-QUAM] AM stereo "component" home radio and Sony SRF-42 AM/FM stereo radio)
Kirk Bayne
Just rehabbed my Pioneer TX7500 that has a CQUAM decoder installed.
I still have one and it worked good on CQUAM and Kahn stations.
The SRF-A100 is a "forced stereo" receiver, so in AM ST mode, you should hear it trying to decode the signal in stereo regardless if the station is actually broadcasting in stereo or not. A neat trick is to switch it into Kahn mode on a signal squeezed in between two others. Adjacent-channel interference on the lower sideband will be heard in the left channel and interference on the upper sideband will be heard on the right channel. A station transmitting Kahn Power-Side (if any of those are left?) will be heard mostly in one channel.
SDR Console v. 3.1 and later has a "Binaular" mode that places the lower & upper sidebands to left & right channels.
It helps pick out the weaker co-channel DX.
Used with a Software Defined Radio.
It helps pick out the weaker co-channel DX.
Used with a Software Defined Radio.
- Status