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Hi-Per Mite

HI-PER-MITE
An Active Audio CW Filter
Designed by David Cripe, NMS

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Temporarily out of stock
A new run is planned very soon.

Kitted and Offered For Sale By The Four State QRP Group

The 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 NMS, 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
Parts List
Assembly Manual in Spanish Translation by Jon Iza EA2SN, thank you Jon.
Parts List in Spanish Translation by Jon Iza EA2SN, thank you Jon.
Assembly Manual in Portugese Translation by Ed Freitas PS7DX, thank you Ed.
Schematic
Part Layout
Want a different center frequency? Here's How.
Center frequencies in Spanish Translation by Jon Iza EA2SN, thank you Jon.
AA7EE Dave Richard 's incorporation into a DC receiver.  Posted with permission, thanks Dave.
AA7EE Dave Richard's YouTube video of the Hi-per-Mite in action.  Posted with permission, thanks Dave.
BX2ABT Hans Fong's You Tube Video Review  posted here with permission.  Thanks Hans.
75 wpm dit performance by Chuck Vaughn, AAHW posted here with permission.  Thanks Chuck.
Audio Bandpass Test by Chuck Vaughn, AAHW This is an audio file and a must listen,  Thanks Chuck.
K9PL's Review  in the K9YA Telegraph  (posted here with permission)  Thank you Philip.
NMS Original article in 73 Magazine  click to turn the pages.
Photo Page
Elecraft's Excellent Capacitor Identification Page  Posted with permission.
Electronics 2000's Excellent Resistor Code Graphic Calculator  Posted with permission.

 
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