Four State QRP Group

Four State

K8IQY Magic Box
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K8IQY MagicBox
Solid State, Electronic, Transmit/Receive Switch

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K8IQY Magic Box Group
This Kit Has Been Retired

Announced at OzarkCon 2010
Kitted and Offered For Sale By The Four State QRP Group

Code named MagicBox during development, this all solid state fully functioning microprocessor based T/R switch is truly a "Magic Box". It was designed by Jim Kortge, K8IQY, to provide seamless tranceiving using separate transmitters and receivers It is extremely user friendly, in fact it's fully automatic, and absolutely silent. It completely protects your valuable receiver, and it is fully compatible with any transmitter final design up to 10 watts. AND it tracks beautifully up to at least 50 WPM!

All that is neccessary is to plug in your antenna, receiver, transmitter, keyer or straight key, and begin sending. It is then exactly like using a tranceiver. The switch provides full QSK (semi if desired), sequenced T/R switching between the receiver and transmitter, plenty of protective isolation between the receiver and transmitter, a smooth sidetone, and receiver audio muting, To our knowledge, a TR switch with these features has never been offered before by anyone, either large company or club, and is not available anywhere - except here!

The kit includes all the parts required to the build - PC Board, ALL connectors, programmed controller, transistors, caps, diodes - everything but the enclosure and power plug. A Ten-Tec TP41 enclosure or similar is recommended. NO SMD's, all parts are thru hole parts.

First time builders please note: This kit is not difficult to build. The pc board is large with plenty of space between components for easy installation. There are NO SMD's, all parts are thru hole parts, and all connectors are board mounted to eliminate point to point wiring.

Specifications and Design Features
  • Creates transceiver operation using a separate receiver and transmitter.
  • Completely automatic operation.
  • Greater than 80dB isolation between the transmitter and receiver during transmit.
  • All solid state MOSFET switching.
  • Negligible receive or transmit signal loss through the switch.
  • Sequenced switching ... the receiver is off first and on last compared to the transmitter.
  • The receiver audio is also switched to provide complete audio muting during transmit.
  • Smooooth 700Hz Sine Wave Sidetone
  • Fully automatic Full QSK up to 50 wpm. Semi QSK can be jumper selected.
  • Tested at 10W and probably will safely go higher.
  • Covers all HF ham bands, 160-10 meters.

    ALL documentation required to build the kit is listed here, just click the links below.
    Assembly Manual
    Assembly Manual in Spanish - Translation by Jon Iza EA2SN, thank you Jon.
    R46 Note: 100 ohms is now being shipped rather than the original 10 Meg.
    Schematic Page 1
    Schematic Page 2
    Auxillary keying circuit for transmitters requiring keyed power supply voltage, i.e Glowbug,TT2, etc.
    Photo Page
    Magic Box Case Print Orientation STL File
    Magic Box Case Top Print Orientation STL File
    Easy Hookup (plug and play)
    Drill/Punching Template for Ten Tec TP-41 Enclosure Doubles as front Panel Label.
    K8IQY's OzarkCon 2010 Presentation (.pdf)
    K9PL's Review  in the K9YA Telegraph  (posted here with permission)  Thank you Philip.

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