Four State QRP Group

Four State

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Designed by
Jack Purdum W8TEE
and Al Peter AC8GY

Click to join the T41 Support
and Information Group
Click for larger image.

Kitted and Offered For Sale By The Four State QRP Group        




This is a complex kit designed to be an experimental platform. I takes some skill and prior experience to have a successful build.
If you are new to the hobby or kit building and looking for a cheap kit to get on the air, this kit IS NOT for you.

If you have limited experience and still want to give it a go, ask your local club members or other hams
you may know for help before you buy the kit so you know that you have a support group behind you.
In addition, use Jack and Al's web site and our T41 reflector (see above) as an information resource
to find solutions in their knowledgebase and answer your questions.

The T41-EP (aka T41) is a robust 20W SSB and CW SDR transceiver, three years in the making by Jack Purdum W8TEE and Al Peter AC8GY. It is an open source project and the radio is designed to be an experimententers platform. Frequently-used settings are quickly changed using the front panel switch matrix. Other,less frequently-changed settings,are modified using a simple menu system. The settings are "set-and-forget" since they are stored in EEPROM. Software and hardware solutions can be easily be changed so experimenters can tailor the rig to meet individual needs. Jack and Al have done their best to make the radio a flexible platform to bring ideas to life and more fun, enjoyment to the hobby.

The radio is built in modules, not as a single board. Different functions can be changed without materially affecting other modules and their processing. The Teensy 4.1 microcontroller is the heart of the T41 and has 7.9MB of flash memory for program storage and 1MB for data. The microcontroller performs all of the T41's SDR functions; no PC, laptop, or tablet needed. The T41 has the horsepower to do the heavy lifting a high performance SDR radio demands, thanks in part to its 600Mhz clock compared to an Arduino Nano's clock at 16Mhz. Then, keep in mind that, despite all of the functionality packed into the T41, you still have over 7.6MB of memory to experiment with if you wish!
Review all the functions below and imagine the benefit of having this radio active on your operating station.

The large (1206) SMD components are already soldered on the boards, making this kit easy to assemble. Most of the construction is mounting the controls and connecting them to the T41 boards, as shown here:

The T41 is a bargain considering all of the functionality built into it. It is a robust SDR transceiver costing a fraction of other SDR radios cost with fewer features. We think you will be amazed at the T41's price/performance ratio! It will make a fine, fully functional, and educational rig for a new builder, the new ham, or seasoned veterans wishing to just have fun with a new rig or have an cost-effective experimentation platform.

Specifications and Design Features

       Feature Set of T41-EP

    --Seven band (80-40-20-17-15-12-10M) HF transceiver
    --SSB/CW with user-adjustable power from 1 to 20W
    --Teensy 4.1 microcontroller (hence T41) with the PJRC audio board
    --Designed for experimentation (hence EP for Experimenter's Platform)
    --Builtin SD card for reading/writing.
    --5" TFT SPI color display (800x480) (not included) for supplied case (7" or 9" with your case)
    --Standalone (no external PC, laptop, or tablet needed)
    --24-bit ADC/DACs allowing up to 192KIHz spectrum displays, perfect for hunt-and-pounce operating.
    --DSP Filters with adjustable bandwidths, flat band passes, and cliff-like skirts
    --Three Noise limiters: 1) Kim, 2) Spectral, and 3) Least Mean Squares
    --Auto-notch Filter
    --Spectrum Display Zoom (bandwidth from 12kHz to 192kHz)
    --14 Band Receive Equalizer
    --14 Band Transmit Equalizer
    --Mic compressor
    --Adjustable Frequency Increment (10, 50, 100, 250, 1000, 10000Hz)
    --Front, Rear, or Both Input Jacks (e.g., Phones, Mic, PPT, key)
    --Provision for speaker output
    --S Meter with dBm measure
    --Two VFO's and Split
    --AGC (Off, Slow, Medium, Fast)
    --Realtime Audio Display plot
    --Four encoders: 1) Main tuning, 2) Fine Tuning, 3) Filter Adjustment/Parameter Menu Setting, 4) Volume
    --You can also now directly input any frequency from the front panel.
    --Push Button Switch Matrix for Commonly-Used Features (menus for less-often used settings)
    --EEPROM storage (optional micro SD backup) for user-adjustable settings
    --Keyer (5 to 60WPM)
    --Keying: Straight key or Keyer with paddle flip
    --New Alp CW Decoder See it in action
    --Simultaneous spectrum, waterfall, and audio displays
    --Bearing feature that gives azimuth beam angle customized for up to 10 QTHs
    --Ability to store/ recall 10 "favorite" frequencies (user-expandable)
    --USB input for easy software updating
    --Open Source hardware and software (Gerbers, BOMs, Schematic, and Source Code available online)
    --7 small PCBs to encourage experimentation
    --Large SMD (1206) components
    --No additional programming required...just load and go
    --Builtin speaker or headphone output.

    --Uses 12V to 13.8V power source


    Al and Jack have written a 500+ page book that explains the theory and construction of the T41-EP.
       An updated version (B0D25FV48C)is now available from Amazon.
       The book has over 130 reviews, 85% of which are 5 Star..

      Builders Manual Jan 5 24 Update

      Board Interconnect Layout

    Electronics 2000's Excellent Capacitor Identification Page  Posted with permission.
    Electronics 2000's Excellent Resistor Code Graphic Calculator  Posted with permission.

The T41 is carefully kitted by Jim Pruitt WA7DUY and Ron Potter and is shipped by Ron Poter, AG1P
Please direct shipping, kit, and part related questions to Ron AG1P

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