March 16, 2020 at 12:52 pm #45130billmcfParticipant
FYI, KBPS 1450 AM did not switch to “Teen Sound” today at 6 am, apparently due the school shutdown. Although I’m a fan of the oldies format, for the students’ sake I hope that the shutdown is a short one.
P.S.: A few days ago, I bought a high-fidelity AM stereo tuner and have been enjoying the extended high-end and stereo sound on KBPS. The station sounds great!March 16, 2020 at 2:30 pm #45132
I went home for lunch this afternoon and listened to the KBPS oldies on a modified tuner. I am in downtown Hillsboro, so the signal strength here isn’t very high. There was a small amount of platform motion. Nevertheless, it is nice that we have at least one station in this are using C-QUAM. That is one more than most cities have. I really miss Sunny 1520.March 16, 2020 at 2:57 pm #45133jr_techParticipant
“A few days ago, I bought a high-fidelity AM stereo tuner”
An item almost made out of unobtainum! What did you get and how did you find it?March 16, 2020 at 3:46 pm #45134billmcfParticipant
I bought a Denon TU-680NAB from eBay. It’s in excellent condition and works very well with a good antenna. I connected it to my outdoor shortwave loop; with an indoor loop the reception was inconsistent. The FM performance is also excellent.
This tuner was introduced the early 90s, in conjunction with the roll-out of AMAX. I wanted to buy one at the time but couldn’t afford the $1200 in today’s dollars. But a used one for $180? Sold!March 16, 2020 at 5:37 pm #45138
When I first read about AMAX in Radio-Electronics magazine in the early 1990s, I longed to hear one of these radios. I attempted to build a radio that came close to the spec–save for the 10 kHz whistle filter, which I soon learned was important. In 1994, I was able to buy a production radio with the AMAX logo, a Sony SRF-42. As this was a small portable, the frequency response and distortion specs were somewhat relaxed compared to those of home and automotive receivers meeting the specification.
The same articles mentioned the expansion of the AM band to 1700 kHz. When I read that, I re-aligned the front ends of all my analog AM radios in preparation for the new stations. Years later, in the winter of 1995, I heard the first one, WJDM 1660, Elizabeth, NJ. I remember listening to it on the homebuilt receiver, in stereo. The format was Radio Aahs.March 16, 2020 at 7:33 pm #45142
We normally play Oldies on non student days. Students are expected to return on April 1st.
https://www.pps.net/site/default.aspx?PageType=3&DomainID=4&ModuleInstanceID=1492&PageModuleInstanceID=1594&ViewID=ad4d6d9d-7046-48e7-a548-a6a23a68d076&RenderLoc=0&FlexDataID=152442&PageID=1&IsMoreExpandedView=TrueMarch 17, 2020 at 1:34 am #45146semoochieParticipant
I thought platform motion had been remedied.March 17, 2020 at 10:09 am #45151
I have to disclose that my experiences are largely limited to using receivers based on Motorola’s classic MC13020P and integrated circuits by Sony and Toshiba of very similar design. These integrated circuits use a phase locked loop to recover a local copy of the station’s carrier, as these integrated circuits are based around synchronous demodulation.
My understanding of the platform motion problem is that it rears its ugly head when the beat notes between the carriers of two co-channel stations cause the combined phase to move around in such a way that the PLL cannot keep up. Either the change is too fast or it at a frequency at which the PLL control loop “rings,” thus exacerbating the effect.
There was a “hack” way of receiving AM stereo that was correct for Magnavox and Harris but not technically correct for C-QUAM. This involved using an FM detector to receive the L-R and then sending the output through an integrator. I haven’t experimented with this. I can say that some analyses performed by a member of one of the AM stereo groups I used to follow, the book AM Stereo and TV Stereo: New Sound Dimensions, plus my experiences listening to WOWO in the early 1990s–which was a “hacked” Magnavox station, not a C-QUAM station–firmly cemented the notion in my mind that Magnavox, Harris, and C-QUAM all put very similar signals on the air. The differences between the systems were designed-in primarily to satisfy patent attorneys.March 18, 2020 at 11:00 am #45195
Looks like KBPS will be playing Oldies through April 28th.April 8, 2020 at 8:36 pm #45682
KBPS will be playing Oldies at least through June. KBPS students are still learning broadcasting in a Home Based Distance Learning environment.
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