Model: MW-2A PLL Tuner Front with integrated signal strength bar graph meter

(((( S-T-E-R-E-O )))) TUNER !!

New custom hand-made 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 new 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.
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.
  • 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!
  • RECEIVED SIGNAL STRENGTH INDICATOR BAR GRAPH METER -- This (added option "SSM") integrated feature visible on front panel 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 for the greatest number of green lit bar segments on your MW-2A PLL tuner!  This indicator is integrated into the rather large, bright, high contrast 24-segment green digital numeric frequency display (14.2mm, 0.56" height) on the right side.
  • 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 anywhere in-between these band edges on the station dial.
    We also 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 support and 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 (non-switching) mode type power supply with each sale, capable of stepping down your local A.C household utility power to +12-volts D.C, tip positive.   This power supply is ultra quiet and does not create any new noise or interference during use.   You could also power your tuner from an external +12-volt D.C battery source, or uninterruptible power supply source.
    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 other small pieces.

    MW-2A PLL Tuner

    Each MW-2A PLL tuner is packed with the features, performance, and price that makes it THE LEADER among all AM Stereo tuners available today, as the winner in fit, function, and performance.
    MSRP: $350.00 USD, and free shipping to domestic U.S.A destinations. Please inquire about any current international shipping restrictions or shipping delays.

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

    Time to Come Clean on AM Quality

    Someone explain to me why radio manufacturers still have not accommodated the NRSC standard.

    By Larry Langford

    Larry Langford
    The author is owner and chief engineer of WGTO and W246DV in Cassopolis, Mich. His commentaries are a recurring feature at
    Reprinted here with written permission from the author.

    I have written in recent years about AM quality, including modulation and bandwidth.   There have been several articles from many other experienced and qualified engineers as well.

    Today, I want to ask a few questions and set the stage for answers that seem to have evaded us for more than three decades.

    A brief history

    AM radios were at one time rather broad in their front-end response.   And while that sounded pleasant, that broad front end caused trouble as the band became packed with more stations.   The typical receiver delivered degraded audio, as its wide front end let in adjacent signals that made listening less enjoyable, especially at considerable distances.

    The problem was exacerbated by AM stations running boosted high-frequency audio at full unrestricted bandwidth, as the audio demanded.

    As a response, manufacturers tightened up the I.F so the audio output was less affected by adjacent-station high-frequency modulation.   We then saw years of tit for tat.   Denser modulation with high-frequency boost was met with more narrowed response by radio manufacturers.

    The battle went on, until AM sounded more like telephone audio, than a quality audio service.

    In the 1980s, the National Radio Systems Committee set out the honorable goal of standardizing transmission equalization, with pre-emphasis that was matched by complimentary de-emphasis in receivers.   The goal was a much improved end-to-end listening experience, one that could approach the sound of FM in new radios.

    The FCC adopted the transmission pre-emphasis, along with a bandwidth limit, or mask, for modulating audio with a cutoff that was as sharp as the edge of the Grand Canyon, blocking anything over 10kHz from making it onto the air.

    Receiver manufacturers said they would soon open the front ends of typical cars and home radios once the new pre-emphasis and cutoff were adopted.

    Fact is the mask cutoff worked so well that you could sit five miles from a 50kW station and tune to a 1kW first-adjacent 80 miles away and hear it with no interference from the nearby flamethrower on just about any modern car radio.   For the casual listener on a consumer radio, the days of adjacent interference were over.

    The present

    It has been more than 30 years since that agreement was made at the NRSC table, more than a generation since the plan was drawn up.

    We have gone through many phases since then -- C-QuAM stereo, which died.   AM hybrid digital, which frankly sucked.   And now finally a move to go all-digital.

    But we know that analog radios will be around for years to come.   Most of the senior engineers from the manufacturers, who were working in the 1980's, have long since passed away.   But the standards that were supposed to change never did.

    I often wonder why the NRSC or NAB could not twist some arms, and why the FCC left the room when asked to mandate the new receiver standards; but that is another story.

    AM portable and most car radios still have audio response that rolls off like a ski slope after 2kHz.   But every station in the United States and some other areas have adopted the 10kHz cutoff.

    The question and challenge

    A lot of people read Radio World, so I am looking for someone to answer the question in technical detail of why, after all these years and tests, the standard AM radio is still unnecessarily narrow and bad-sounding.

    I want someone with credentials as a manufacturer to step up and tell us what possible reason they have for not re-doing the basic chipset in 30 years to accommodate the NRSC standard.

    The argument has gone on for decades, but I have never seen a written word from any trade group or individual representing radio manufacturers that really explains this position.

    Manufacturers promised the NRSC they would make radios to compliment the new standard, even though the FCC never made the receiver improvement mandatory, while making every radio station modify transmission systems to meet the new standard.

    Makers did respond quickly to the expanded band, cranking out radios that went to 1700kHz at record speed; and now they are slowly making digital radios for more car models.   But no one took the simple step of changing the mass-produced chipsets to something that would better resemble decent fidelity since 1988.

    Someone tell me why improvements were not made to increase bandwidth to any reasonable degree.   Is there a political answer?   I cannot think of an engineering answer, but I wish to open the floor for someone to stand up to explain this archaic practice of tightly limited AM bandwidth -- at a time when most AM listening is local, and adjacent interference at that range is rare.   Is there anyone from the manufacturing side who will offer testimony?   Is there someone to come forward or will we hear only country crickets in the night?


    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.

    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).
    Send email.
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