[CW] NM0S - HyperMite 200 Hz Audio Filter - NO RINGING!

D.J.J. Ring, Jr. n1ea at arrl.net
Thu Mar 24 13:34:50 EDT 2022 

Walter,

Thanks for writing.

Hans mentioned a need for a 400 Hz filter, I just punctured my ear drum due
to a nasty infection so I'm a candidate for low frequencies also.

I wonder if you might interest them in putting out a lower frequency
version?

73
DR



On Thu, Mar 24, 2022 at 1:50 AM Walter - K5EST <walter.k5est at gmail.com>
wrote:

> David, the Hyper-Mite is a real addition to  a station even at the QRQ
> level.
>
> Until medical knocked me down, I was the Kit Manager for 4 State QRP.
> Keeping electronic components available was tough because sales were
> stronger than the supply chain.
>
> Chuck - AA0HW has a research report on the filter, it's listed in the
> sales page.
>
> 73,
>
> Walter Dufrain - K5EST - QRPcw
>
>
>
> On Wed, Mar 23, 2022, 21:26 D.J.J. Ring, Jr. <n1ea at arrl.net> wrote:
>
>> This looks like a good piece of kit, http://www.4sqrp.com/HiPerMite.php
>>
>> Does anyone have one of these?
>>
>> If so, do you like it?
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>> *HI-PER-MITEAn Active Audio CW FilterDesigned byDavid Cripe, NMØS[image:
>> JPEG Not Uploaded Yet]
>> <http://www.4sqrp.com/kits/filter/cwfilterdarpic2big.jpg>Click for larger
>> image.Kitted and Offered For Sale By The Four State QRP GroupThe
>> HI-PER-MITE is a HIgh-PERformance SMALL audio filter. It is designed to be
>> very versatile, have low parts count, be inexpensive, yet provide
>> outstanding performance. This is a flexible design that can be used as a
>> stand-alone unit driving headphones, earbuds, or speakers, or it can be
>> easily integrated into an existing receiver needing additional CW filtering
>> (see manual for details).Designed by David Cripe NMØS, it features a 200
>> cycle bandwidth with NO RINGING! It can be used as an external stand-alone
>> unit with an onboard audio amp for driving a speaker or headphones. It also
>> can be built into a receiver without using the audio amp, or with it if you
>> need an audio stage. This is a very useful accessory for direct conversion
>> or other rigs needing additional selectivity. It removes/reduces signals
>> and noise outside the 200HZ passband, and also power line hum in Direct
>> Conversion receivers. Thus providing comfortable listening while using
>> earbuds, headphones, or a speaker. If you have a direct conversion
>> receiver, you will love this filter.The HI-PER-MITE is a much improved
>> version of Dave's HI-PER Audio Filter circuit that was published in the May
>> 1994 issue of 73 magazine. If you wish to learn more about the genesis of
>> the HI-PER Mite, and learn about important audio filter design parameters,
>> click on the original 73 article link in the documentation section
>> below.This low cost kit sacrifices nothing in the way of quality. It
>> features a high quality printed circuit board, low parts count, all through
>> hole parts, and fast and easy building. It is an excellent kit for first
>> time builders, and was chosen as the Buildathon kit for OzarkCon
>> 2012. First time builders please note: This kit is not difficult to build,
>> there are NO SMT parts and the parts are wide spaced on the board making
>> installation easy.    Specifications and Design Features    Bandwidth:  200
>> cycles at the -3 DB bandwith points.    Center Frequency:  The center
>> frequency in the passband is 700 HZ    Signal Gain:  0 dB to 50 dB, user
>> selectable    No Ringing or Buzz:  Nice, smooth audio - care has been taken
>> in the design to eliminate ringing.    Versatile:  Drives speaker, earbuds,
>> or headphones. Use standalone or install inside rig.    Audio Power:  500
>> mW into 8 ohms, from 9v supply    DC Power:  5 to 13 VDC at less than 15
>> mA    NO SMT Parts:  All through hole parts..    NO Toroids:  There are no
>> toroids to wind, special circuits simulate them.    PCB:  High Quality,
>> silk screened, two sided 2.2"x1.5" printed circuit
>> board.    Documentation    Assembly Manual
>> <http://www.4sqrp.com/kits/filter/cwfiltermanual4.pdf>    Parts List
>> <http://www.4sqrp.com/kits/filter/cwfilterpartslist5.pdf>    Assembly
>> Manual in Spanish
>> <http://www.4sqrp.com/kits/filter/cwfiltermanual4_es.pdf> Translation by
>> Jon Iza EA2SN, thank you Jon.    Parts List in Spanish
>> <http://www.4sqrp.com/kits/filter/cwfilterpartslist4_es-1.pdf> Translation
>> by Jon Iza EA2SN, thank you Jon.    Assembly Manual in Portugese
>> <http://www.4sqrp.com/kits/filter/cwfiltermanual4_pt_br.pdf> Translation by
>> Ed Freitas PS7DX, thank you Ed.    Schematic
>> <http://www.4sqrp.com/kits/filter/cwfilterschematic3.gif>    Part Layout
>> <http://www.4sqrp.com/kits/filter/cwfilterpartslayout.pdf>    Want a
>> different center frequency? Here's How.
>> <http://www.4sqrp.com/kits/filter/cwfilter_f_vs_r_table_2.pdf>    Center
>> frequencies in Spanish
>> <http://www.4sqrp.com/kits/filter/cwfilterfreq_es.pdf> Translation by Jon
>> Iza EA2SN, thank you Jon.    Center frequency Calculator by Paul Jorgenson,
>> KE7HR.
>> <http://www.4sqrp.com/kits/filter/hpmfrequencycalculation.xls>    AA7EE
>> Dave Richard 's incorporation into a DC receiver.
>> <http://aa7ee.wordpress.com/2012/07/27/using-the-nm0s-hi-per-mite-filter-from-4sqrp-to-make-a-simple-40m-dc-cw-rx/>  Posted
>> with permission, thanks Dave.    AA7EE Dave Richard's YouTube video of the
>> Hi-per-Mite in action. <http://www.youtube.com/watch?v=jc7e9VYgubk>  Posted
>> with permission, thanks Dave.    BX2ABT Hans Fong's You Tube Video Review
>> <http://www.youtube.com/watch?v=Pk_GFJsux24&feature=plcp> posted here with
>> permission.  Thanks Hans.    75 wpm dit performance by Chuck Vaughn, AAØHW
>> <http://www.4sqrp.com/kits/filter/cwfilter_75wpm_dit_performance.pdf> posted
>> here with permission.  Thanks Chuck.    Audio Bandpass Test by Chuck
>> Vaughn, AAØHW
>> <https://soundcloud.com/chaseology/hi-per-mite-audio-bandpass> This is an
>> audio file and a must listen,  Thanks Chuck.    K9PL's Review
>> <http://www.4sqrp.com/kits/filter/k9yatelegraphfeb2013hpm.pdf> in the K9YA
>> Telegraph  <http://k9ya.org/> (posted here with permission)  Thank you
>> Philip.    NMØS Original article in 73 Magazine
>> <http://www.archive.org/stream/73-magazine-1994-05/05_May_1994#page/n11/mode/2up>  click
>> to turn the pages.    Photo Page
>> <http://www.4sqrp.com/kits/filter/cwfilterphotopage.html>    Electronics
>> 2000's Excellent Capacitor Identification Page
>> <https://www.electronics2000.co.uk/calc/capacitor-code-calculator.php>
>> Posted with permission.    Electronics 2000's Excellent Resistor Code
>> Graphic Calculator
>> <http://www.electronics2000.co.uk/calc/resistor-code-calculator.php>
>> Posted with permission.*
>>
>> 73
>> DR
>> N1EA
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