Many thanks to SWLing Post contributor, Dave (N9EWO), who writes:
Dan, shango066 on You Tube give us a nice little tour of KYET on 1070 kHz in Golden Valley Arizona which transmits in AM Stereo (6K day, 1 watt night). Harris solid state transmitter which is also shown in this video:
Click here to view on YouTube.
First part of his video explains the modified Realistic receiver (which he could not get working, well at least not yet):
AM stereo was a great idea that the FCC turned into a joke. Only the truly dedicated and idealistic radio lover will try to transmit or receive it. I love listening to a broadcast engineer talk about his/her craft; after decades in the industry, the engineers have always been the most interesting characters I met.
The joke continues
No plan to convert analog AM invented in 1910 and FM radio invented in 1936 to digital.
The telcos switch off the oldest generation every 8 years.
AM contains a carrier which is 67 – 100 % of the radiated signal power. It contains no information, it is used to bias the diode detector in the radio to minimise distortion. It is included in all digital HDRadio in the AM band. There are no broadcasters radiating all digital FM HD so the digital signal is only 6 % of the FM power. HD2 – HD4 is even weeker.
Instead DRM in the virtually deserted analog TV channels 2 – 6. There is no carrier, it only requires 10 % of the FM transmitter power and the data rate available is up to 186 kbit/s instead of 96 kbit/s. It can show a slideshow, multipages of indexed text as well as 3 music quality programs per 100 kHz wide channel (FM stereo 200 kHz wide, HD radio with FM 400 kHz). Now 6 adjacent channels through a single transmitter ie 18 programs all at the same power level as each other.
https://www.fcc.gov/consumers/guides/plan-ahead-phase-out-3g-cellular-networks-and-service
Broadcasting is like ham radio where boat anchors are allowed. You can turn on your car made in the 50’s or before running tubes & a vibrator and receive an AM MW signal in 2022. DRM etc is of course far more spectrally efficient. The FCC recently deciding to allow some stations to go all-digital (with the catch its ibiquity’s HD radio, sigh) is a step forward in that direction but at the cost of more interference (read my updated comment below).
As for cells / mobiles, those carriers paid for a certain amount of spectrum and they absolutely HAVE to use it as efficiently as possible. Only LTE and New Radio do this. The old standards just don’t work nearly as well with either high speeds and lots of user terminals (what LTE was made for) or IoT (5G NR).
ZOMG I drive by this stick every time I go home & visit family (or vice-versa) between Phoenix & Reno! I thought it was off the air & equipment removed, just leaving the stick. I sure didn’t know it was AM stereo!
It’s hard to tell from the video, but this stick is in one of the stranger locations for an AM station, the top of Coyote Pass between Kingman (proper) & the famous Route 66, and Golden Valley; the Arizona State Route 68 at the beginning goes to Bullhead City and across the river to Laughlin, Nevada (southern-most town). To the north (on US-93) is Hoover Dam and Las Vegas, around 90 minutes away (depending on how much lead is in your foot).
Radio Locator won’t even show it on a local search (beyond “fringe” coverage); local station KNUV 1190 would definitely interfere @5kW day. Obviously a single legal watt at night would be tough for even the most hardcore DXer to catch KYET, though! 😉
This was a great video and it’s amazing early 80’s tech (more advanced than I thought but still no surface mount).
I’ve been thinking of moving out of Phoenix, I wonder if they’re hiring?
Update: it’s impossible to receive down here 150 air-miles (as the crow flies) other than some carrier on an SDR water-fall.
Worse still and unbelievable irony: KSL 1160 from Salt Lake City is a 50kW Class-A omni 24/7 and broadcasts ibiquity’s HD Radio which eats 30 KHz and would likely make night reception impossible even closer than Radio Locator shows; I wonder if they don’t just shut it off at night?
Fascinating video. Thanks for posting this.
Here’s a good comparison of mono vs. am stereo,click on their audio advantage link
at right:
http://www.amstereo.org
The mono receiver in that ‘comparison’ not alone is mono-only on AM, but also has a very narrow audio bandwidth/roll-off (much less than transmitted) ., so isn’t a like-for-like comparison of mono and stereo. I have mono AM receivers (especially older dial-tuned ones) which sound far far better than that on any good quality interference free AM signal.
A better comparison is to enable and disable AM stereo on the SAME (AM stereo) receiver.