Federal Communications Commission was seeking electronic comments in its filing system to revitalize the AM radio service broadcast band in the United States until January 21, 2014.   This was our chance to be heard on this important issue!

Brian J. Henry of Napa, California, completely understands what needs to be changed for the AM broadcast band to be revitalized!  Brian writes, "Without an improvement in AM broadcast receivers, there can be no AM revitalization!  The single biggest factor in the technical decline of AM broadcasting lies with the deterioration in receiver performance.   The vast majority of AM broadcast receivers do not have wide bandwidth audio frequency response that matches the transmitted audio frequency response, and their audio frequency distortion performance is orders magnitude worse than that of the worst commercial AM broadcast transmitter ever manufactured.   I believe that the public interest would be served by The Commission mandating an analog audio quality standard for AM broadcast modulation and demodulation with flat end-to-end audio frequency response from 50Hz to at least 7.5kHz- with a 10kHz receive notch filter, and low audio frequency distortion that is modeled after the Electronic Industries Association and National Association of Broadcasters AMax certification program to help AM regain some of its technical footing."   We agree with Brian's comments and also support the AMax initiative, authored more than 20 years ago, and still worth its weight today.   In order for AM fidelity to improve, there has to be received analog audio fidelity complemented by the broadcast audio fidelity.

Matt Krick, AM music station engineer, writes to the FCC: "It has come to my attention that the vast majority of AM receivers on the market are designed with 'Good Enough' mentality and quite frankly make anything received sound like mud.   I'd like to propose the FCC implement requirements for manufacturers of radios to actually design a decent performing receiver."

Say good bye to muddy sound. ...

meduci has answered your calls!   Wideband high fidelity AM digital tuners are available from meduci since 2005.   Unlike conventional AM radios, meduci tuners are optimized for music, and reproduce many limitations of the air interface and AM station's transmitter.   This increased fidelity and crisp reproduction of the transmitted source program material may now be fully enjoyed and appreciated by the audiophile expert.   For the first time in radio history, AM fidelity is not strictly limited by the receiving equipment.

Virtually all other available AM medium wave receivers and tuners drop audio fidelity to 2.0kHz maximum recovered audio frequency response.   This is good for a telephone conversation, however not for long-term listening sessions to high definition music programing.

Will the FCC mandate that all manufacturers to build and to sell higher fidelity AM radios?  This is not likely.   FCC is not in the business to advocate how well an AM radio receiver sounds or receives stations in its overall performance.   Can the FCC stop the HD Radio madness on the AM broadcast band?  Yes, definitely!

Brian J. Henry further writes, "The vast majority of licensed AM radio stations are not embracing in-band / on-channel digital operation and those that are only exacerbate an already bad situation with regard to interference to analog operation, particularly at night.   There is unfortunately no way for there to be a high fidelity analog AM broadcast transmission system when there is a digital service operating in the audio pass band between 5kHz and 15kHz.   The current combination approach is not benefiting either technology.   They simply are not compatible.   I feel that the public interest would be better served if the Commission authorized full AM digital operation at the broadcaster's discretion in lieu of analog operation.   Implementing AM stereo may be a viable path forward for AM broadcasters until enough digital receivers have been acquired by the public to make the switch to all-digital transmission a worthwhile consideration, especially since some recently manufactured HD receivers are able to decode C-QuAM AM stereo."

WBT "NewsTalk 1110" in Charlotte, North Carolina conducted an all-digital HD Radio test broadcast on August 18, 2013 to meaure the strength and fidelity of their broadcast.   We heard this all-digital HD Radio test broadcast, and we were not impressed with the WBT HD audio sound quality.   It was far from being exceptional.   In fact, it sounded very artificial, especially when music snippets were played.   This all-digital transmission method will not revitalize the AM broadcast band.   WBT also reportedly used an omni-directional pattern during the all-digital test, since their directional pattern was not up to the task.   WBT has not conducted subsequent tests, and we can only conclude that the all-digital test failed.

During their promotional announcement, it was stated, "WBT is one of a handful of radio stations in America that is capable of broadcasting in digital HD."   We agree with that statement.   There are many technical reasons why HD Radio is not more widespread, especially for night-time AM broadcasts.

What can you do to receive better sounding analog AM radio broadcasts?  meduci sells quality wide band high fidelity AM stereo tuners and decoders intended for the C-QuAM stereo format.   Our newest model, the MW-2A PLL tuner, boasts recovered audio bandwidth beyond 10kHz in the "wide" mode, and 3kHz bandwidth in the "narrow" mode.   This fidelity competes with other media devices.   Our tuner is the answer to the availability shortage for high fidelity AM tuners today.   Overall, our highly effective tuners are intended to be a large part of the AM broadcast band revitalization process.


Model: MW-2A PLL Tuner Front


New MW-2A PLL medium wave AM broadcast band home consumer electronic tuner is available, which has phase-locked loop electronic digital tuning system, and a very special AM stereo section.   This solid state audiophile component tuner is quite unlike anything else: it is wide band, and has a Motorola C-QuAM stereo decoder, showcasing natural sounding high fidelity, with very low audio distortion!   Our goal was not to build a low fidelity AM tuner for this offering.   This economical tuner also does not share its chassis with any FM tuner components.   It is exclusively the AM tuner!
Audition one of our tuners, and you will be astounded: the AM section of this meduci even sounds better than AM HD radio.   Because it has none of the digital data audio compression artifacts that make HD radio sound swimmy, wishy-washy, and artificial.
In all honesty, virtually all consumer AM tuners available today, or produced in the past, sound like you are listening through a paper-towel roller, because these inferior sounding tuners roll-off the high and low audio frequencies.   This meduci MW-2A PLL tuner does not eliminate those audio frequency extremes.
We offer one fixed Power-ON Frequency for a radio station air studio application, that can be programmed into your unit at the time of manufacture, in the event of mains power interruption.   Most other tuners will stay off, or will re-tune the tuned frequency to the beginning of the broadcast band, after such a power interruption event.   In either case, it would require someone to intervene to hit their tuner's "power" button in the air studio, in order to turn ON the tuner, and/or to re-tune their tuner to their broadcast station frequency.   Your MW-2A PLL tuner does not have either of those two restrictions.   Default AM station frequency is 540kHz, unless new Power-ON Frequency is specified in advance of tuner shipment.   This frequency is actually stored in the microprocessor's non-volatile memory.   To always re-tune to the station's broadcast frequency.   With this enhancement, expect the entire LED station display panel and the AM stereo indicator to turn off, to preserve its life, when the rear-mounted power switch is pushed to the "downward" position.   Also, the rotary TUNING control knob becomes disabled.   However, the tuner stays powered up, to remember the last tuned medium wave station.   Audio output will also not mute, to keep feeding your audio throughout the air studio reception environment.   Please note that this is normal operation.   In a home consumer environment, when your audio amplifier or self-powered speaker's power is turned off, the sound will also disappear.   Having audio presented to an un-energized amplifier, or to self-powered speaker will not harm your device, though.   Most customers who use their MW-2A PLL tuner at home will switch off their separate audio power amplifier at the same time that their MW-2A PLL tuner is also switched off.   Alternately, they have it all controlled by one master power switch.
Instead of cluttering the front panel with seldom-used buttons and features (such as with some tuners from other sources), this meduci MW-2A PLL tuner concentrates on the essentials, with additional new standard features that increase its curbside appeal:
  • WIDE \ NARROW BANDWIDTH SELECTION -- This standard feature allows you to narrow the tuner's I.F bandwidth for night-time conditions or for "DX-ing" weaker stations.   Being stuck with one extra-narrow or extra-wide audio bandwidth is not all that practical for the different reception conditions that we encounter on the AM band from day-to-night -- this dual bandwidth feature provides your MW-2A PLL tuner with much more versatile operation.   Even at narrow bandwidth, the recovered audio is far superior to most other consumer AM tuners available on the market today.
  • NRSC AUDIO DE-EMPHASIS SELECTION -- Another appreciated standard feature on your new MW-2A PLL tuner is the NRSC front-panel audio de-emphasis curve defeat switch, that improves the overall frequency response from AM broadcast stations transmitting with the NRSC pre-emphasis audio curve.   Very few other AM tuners ever incorporated this switchable NRSC de-emphasis feature.   NRSC pre-emphasis curve is voluntary in U.S.A, so there is not an easy way to know if the AM medium wave station makes use of it, or not.   If the AM station sounds strident in wideband mode, then likely the NRSC curve is being used at that station.   Next station on the dial may not be using it, though.   For that reason, we leave the NRSC feature switchable, and easy to defeat.   This restores the proper audio frequency response, and decreases audio noise up to 10dB at the higher frequencies.   This new feature will not remove local interference from a device in your house or neighborhood.
  • AUTO STEREO \ FORCED MONO SELECTION -- There may be rare instances when a received mono AM station may false trigger the C-QuAM stereo decoder circuitry into action.   In this case, you would want the forced mono selection to be enabled.
  • TWIN-T AUDIO NOTCH FILTERS -- Two high-Q sharp RC filters are always engaged to eliminate annoying inter-carrier "whistle" sounds.   These sounds would be produced from co-channel and/or adjacent medium wave stations "beating" and creating the new notes during crowded night-time listening periods.
  • AUTOMATIC RF NOISE LIMITER -- This very clever circuit reduces high intensity impulse noise pops from the audio output, which improves listening during inclement weather.
  • BRIGHT RED LARGE AM STEREO INDICATOR -- Provides solid confirmation that you are listening to C-QuAM stereo broadcasts (where available).   This AM stereo indicator is not present on any other new receiver offered today, however you can find it on the front panel of your new MW-2A PLL tuner!
  • CENTER TUNING LOCK INDICATION -- This feature provides positive confirmation that your very own AM external indoor tunable loop antenna is centered and locked onto your favorite AM station's signal!  Simply rotate the tuning knob on your attached loop antenna until the center tune lock indicator illuminates on your MW-2A PLL tuner!  This green indicator is integrated into the rather large, bright, high contrast 24-segment green digital numeric frequency display (14.2mm, 0.56" height) in the upper right area.
  • This new MW-2A PLL tuner has rock solid, precise, and stable operation -- with user interface directly under custom microprocessor control -- and this tuner even makes mono AM stations sound better.
    All stations on your MW-2A PLL tuner are drift-free thanks to the Motorola digital Phase Locked Loop synthesizer circuit that provides precise electronic tuning (automatically, of course).   This evolutionary feature eliminates ALL microphonics, unstable operation, and tuning drift, thanks to the highly stable quartz crystal timebase.   Also, the tuning range is NOT condensed in the upper end of the broadcast band, which is typically encountered on ALL manually-tuned radios.   Tapping on the tuning knob, or moving your MW-2A PLL tuner, will not upset the rock solid frequency lock on AM stereo and monaural stations.
    Either 9kHz or 10kHz continuous electronic station tuning steps are included in this phase stable design, set at the time of manufacture, based upon tuner's shipping destination during order placement.   This is intuitive simplicity for manually rotating the tuning knob to your desired AM medium wave station's frequency.   This tuning mechanism does not have any mechanical tuning stops, so you can tune directly, instantly, and simply from the band edges (say from 530kHz to 1710kHz), or in-between these band edges on the station dial.
    We made several cosmetic improvements to the overall external appearance!  These improvements include aesthetically pleasing black exterior, with nice contrasting white lettering on front and rear black aluminum panels.   All is housed in new attractive black plastic cabinet, which measures seven inches long by six inches wide by two inches height (179.5mm long by 154mm wide by 51mm height).
    This professional quality MW-2A PLL tuner is our most advanced tuner offered to date -- updated and re-packaged to build upon the renowned strengths of our two previous consumer AM stereo tuner models.   Most importantly- this new MW-2A PLL tuner has superb ultra high-frequency recovered audio frequency response, that is not found on any other consumer AM tuner nor receiver being sold new today.   Excellent sound, ease of use, and convenient features are all wrapped up in this MW-2A PLL wallet-friendly tuner, ready for a devoted audiophile's tuner collection!   Your MW-2A PLL tuner is designed for high fidelity reception from local and regional AM stations.   With this tuner's dramatically increased audio bandwidth-- undoubtedly, you will hear other sounds that garden variety tuners and receivers simply will not reproduce.   In the process of increasing the audio fidelity-- for better listening enjoyment-- any high frequency noise in your reception environment will also be increased.   We cannot promise a noise-free listening experience, since every reception environment is different.   It is best to get the receiving antenna away from any man-made noise sources for best C-QuAM stereo reception.   Both the NRSC and I.F bandwidth front panel switches will also reduce these recovered higher frequency audio noises, when pushed to their "downward" positions.
    We strive to earn customers for life.   We only want good experiences from our products throughout the world, so we stand behind each and every sale.   We also service our products, if needed.   Please let us know if you any questions, or suggestions for this new and improved, re-designed tuner.
    New meduci MW-2A PLL tuner is currently available for sale to AM stereo fans.   We provide one small linear mode (non-switching) type power supply with each domestic sale in the United States and Canada, capable of stepping down your 120-volt A.C household utility power to +12-volts D.C, tip positive.   For sales outside United States and Canada, purchaser locally sources and furnishes their own linear mode (non-switching) type power supply, capable of stepping down local A.C household voltage utility power to +12-volts D.C, tip positive.   You could also power your MW-2A PLL tuner from an external +12-volt D.C battery source, or fused automotive cigarette lighter power cable.   This tuner is new, hand-made to order, and is directly sold from the manufacturer.   Assembled in the United States of America from U.S and globally-sourced components, parts, and pieces.
    Each MW-2A PLL has the features, performance, and price to make it THE LEADER among all AM Stereo tuners available today, as the winner in fit, function, and performance.

    For MW-2A PLL Owner's Manual, please click on this link.

    Please inquire for further details, and do not forget to mention "AM stereo" (without quotes) in the subject line to bypass our internal junk spam mail filters.   Write to amstereo'AT' (replace 'AT' with the @ sign).
    You can also simply scan QR code using your smart phone or mobile device QR Scanner to send e-mail to meduci:

    Simply scan QR code.


    Kintronic Laboratories

    Bobby Cox and Tom King from Kintronic Laboratories showed their fondness for C-QuAM AM stereo by proclaiming "Come hear what AM Radio can really sound like using today's technology."  They also answered questions in their booth at the National Association of Broadcasters Spring 2014 show, and discussed C-QuAM AM stereo technology and the FCC petition that they organized to improve the AM broadcast band.   Anyone willing to listen to high fidelity AM audio was greeted with a pair of headphones for a shoot-out test.   Both the Carver TX-11a and Sony XDR-F1HD tuners definitely showed the disparate differences in AM tuner audio bandwidth and distortion in these headphones.   Alan Alsobrook and The Broadcasters' Desktop Resource reported on the NAB festivities.

    Tom King wrote letter to the Federal Communications Commission (FCC) on September 04, 2014 regarding the AM Revitalization process (FCC NPRM Docket No. 13-249):

    Subject: Meeting with FCC Commissioner Ajit Pai and Mr. Peter Doyle,
    Chief of the Audio Division of the FCC Media Bureau
    at the offices of the FCC in Washington, DC on Tuesday, September 23, 2014.

    To All AM Broadcasters in the USA:

    Kintronic Labs is concerned about the declining position of the AM radio service in the United States, which we reflected in our Reply Comments to the FCC NPRM Docket No. 13-249 on the subject of "AM Revitalization," issued on October 31, 2013.   In the interest of preserving this great national resource for local public media, we have scheduled a meeting with FCC Commissioner Ajit Pai and Audio Media Chief, Mr. Peter Doyle, to address what we believe are the critical steps toward putting AM radio on a more competitive basis with FM as follows:

    (1) FCC enforcement of regulations relative to the power distribution industry and the consumer electronics industry that are not currently being enforced, resulting in a constantly worsening electromagnetic environment for AM radio service.

    (2) The need for parity between AM and FM receivers through the establishment of minimum technical standards for AM receivers that would become effective as soon as January 2016.   We plan to demonstrate a comparison of full-bandwidth C-QuAM AM stereo reception with a local FM station and with a typical AM receiver in a popular consumer multi-band receiver.   The effects of adjusting the AM bandwidth from 2.5 to 10 kHz in 2.5-kHz steps will also be demonstrated.

    (3) The need for FCC authorization of AM synchronous boosters.   Unlike FM translators, such on-channel boosters would serve to increase the AM stations' audiences while concurrently maintaining the future viability of the band.   The related technique of wide-area AM synchronization for coverage improvement will also be addressed.

    Referring to Step #2, it is absolutely essential that very close to full parity be established for new AM radio receivers versus their FM radio counterparts.   This includes all key AM receiver performance attributes, including:

  • Low internal noise floor, well below the average AM-band atmospheric noise level.   This includes all internal synthesizer and DSP circuitry within the receiver (and in the immediate environment for integrated automotive applications).
  • High overall RF sensitivity, selectivity, and dynamic range, to provide adequate amplification of weak signals, even in the presence of significant adjacent- and/or alternate-channel signals, especially in strong-signal environments.   This would incorporate typical advanced, multi-stage AGC action, with appropriate interaction between the RF and IF AGC control mechanisms to maximize overall receiver dynamic range, including adaptive front-end attenuation for signal-overload protection in very strong-signal areas.   Useful typical specs include: sensitivity - 1 mV for 10-dB SNR; selectivity (adjacent-channel) - 25-50 dB (adaptive).
  • Highly effective noise (EMI) rejection, including staged RF and IF noise blanking, accompanied by appropriate audio blanking and/or expansion when required.   Such features were developed and included in Motorola chip sets in the 1990's in the AMax program, and are easily integrated into modern, high-density AM/FM receiver chips.
  • Full 10-kHz audio bandwidth capability with low detector distortion.   This would obviously incorporate dynamic, signal-controlled bandwidth control (including AMax-style adaptive 10-kHz notch filtering) as dictated by noise and adjacent-channel interference.
  • Stereo capability.   If the receiver has FM stereo capability, it must have corresponding C-QuAM decoding for AM.

    Without fulfillment of the first three requirements (this also includes the associated AM antennas both for vehicles and for home use), basic AM reception will suffer significantly compared with FM.   Without the last two, the output sound quality cannot be closely competitive with FM (i.e., 10-kHz full bandwidth on AM versus 15-kHz nominal for FM).

    We therefore petition the FCC to mandate the following minimum allowable performance specifications for all AM receivers that will be manufactured and installed in new automobiles as of January 1, 2016:

    Audio Bandwidth: 10 kHz typical, adaptive, with a minimum nominal bandwidth of 7.5 kHz
    Signal-to-Noise Ratio: minimum 55 dB, preferably 60 dB
    Sensitivity: -120 dBm for a signal-to-noise ratio (SNR) of 10 dB
    Selectivity: 25-50 dB (adaptive filtering, using co-, adjacent-, and alternate-channel detection)
    Dynamic Range: 100 dB
    Noise Figure: 1 - 3 dB
    Image Rejection: -50 dB
    Intermod: IP2 , IP3 intercepts +10 to +40 dBm
    IF: low with image-rejecting down-conversion, or double-conversion
    Stereo Separation: minimum 25 dB

    Respectfully Submitted,
    Tom F. King


    In 2006, we developed prototype meduci AM stereo tuner for two Chicago AM stations that included the following features:

  • Motorola C-QuAM AM Stereo Decoder
  • Frequency Input: 530 kHz to 1,710 kHz
  • Antenna Input: BNC 50 ohms
  • Balanced stereo audio outputs (left, right)
  • 600-ohm +4dBu balanced audio output standard
  • 12-volt D.C input via class-2 U.L. listed Power
  • Rack-mounted 19" wide EIA enclosure (1 RU tall)
  • Phase Locked Loop Synthesized Tuner
  • Frequency Response: 25 Hz to 15,000 Hz (-6dB)
  • Carrier Sense / Carrier Loss Alarm
  • "Adjustable Carrier Sense" (adjustable threshold)
  • Good flat envelope distortion free bandwidth
  • High Stability
  • Quartz Crystal-Controlled Local oscillator
  • Internal DIP Switch Station Selection (8 bits)
  • 10kHz (Canada, Americas) or 9kHz Frequency Plan
  • Instrumentation-grade low slew rate audio amplifiers
  • Low Harmonic Distortion (under 1%)
  • Full aluminum chassis for maximum RF shielding and durability
  • Can be operated in high RF field environments

    Our newest tuner has all of the above features, as well as the following additional new features:

  • 10kHz Notch Filter
  • AMax Stereo
  • Effective Noise Blanker
  • Switchable Wide / Narrow Audio Bandwidth
  • NRSC-1 75uS audio de-emphasis network

    Balanced audio outputs with XLR male connectors provide uncompromising audio performance for critical listening applications with compatible audio components.

    Each tuner is frequency agile, with drift-free quartz crystal phase lock loop accuracy (down to better than 100 ppm stability).   Each tuner is set to the station's frequency, based upon internal DIP switch selection.

    Loss-of-carrier signal sense (open collector) is also standard, to interface to user-supplied alarm device.   Each tuner can be mounted to standard EIA 19" relay rack.   Antenna input is 50 ohm BNC connection.   Purchaser can also specify either XLR, Euroblock, or 1/4" TRS audio outputs.

    Designed as a general purpose off-air AM medium wave broadcast quality monitor demodulator grade receiver for EAS or other critical applications.

    Each tuner will be priced according to market conditions.   There is an approximate four-week manufacturing lead time.

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