Design Decisions in the High School Direct Conversion Receiver.docx

Design Decisions in the High School Receiver Project.
Why we did it this way.

document - 15.29 kB - 05/29/2023 at 13:10


TJ DCR PO Worksheet - BOM.xlsx

DCR Bill of Materials - quantities for 15 complete receivers with spares

sheet - 19.19 kB - 04/25/2023 at 11:41


TJ DCR Mixer Build Instructions.docx

Building the Mixer - Step by Step

document - 1.17 MB - 04/25/2023 at 11:36


TJ DCR BPF Instructions.docx

Building the Band Pass Filter - Step by Step

document - 707.71 kB - 04/25/2023 at 11:36


TJ DCR Audio Amp Instructions.docx

Building the Audio Amplifier - Step by Step

document - 1002.77 kB - 04/25/2023 at 11:35


Schematic - Band Pass Filter-.jpg

Schematic for the 40 meter band pass filter

JPEG Image - 76.26 kB - 04/25/2023 at 11:34


Schematic - Double Balanced Mixer.jpg

Schematic for the double balanced mixer / product detector

JPEG Image - 98.01 kB - 04/25/2023 at 11:31


Schematic - Full DCR.jpg

Full Schematic for 40 meter direct conversion receiver

JPEG Image - 454.07 kB - 04/25/2023 at 11:30


Schematic - Audio Amplifier.jpg

Schematic for the audio amplifier

JPEG Image - 140.01 kB - 04/25/2023 at 11:30


Schematic - Oscillator and Buffer-.jpg

Schematic for the permeability tuned oscillator and buffer

JPEG Image - 110.08 kB - 04/25/2023 at 11:30


TJ VWS Building the Oscillator Instructions.docx

Building the Oscillator - Step by Step

document - 604.36 kB - 04/25/2023 at 11:26


Winding a Toroidal Transformer (Video).docx

Winding a toroid is often a "show stopper" for many prospective builders. But we wanted the students to have the experience. So we had them wind their own. This video shows them how. They did very well, and will no longer fear toroidal transformers!

document - 12.07 kB - 04/25/2023 at 10:36


N3FJZ Build of Receiver.docx

At our request, many hams around the world built and tested the receiver. Rick N3FJZ was one of them. Rick did an especially great job of testing the circuit.

document - 12.29 kB - 04/25/2023 at 10:34


TJ DC RX in a Simulator.docx

During our preparation, we built the entire receiver in the LTSpice simulator. To our surprise, the ENTIRE RECEIVER (including the oscillator) fired up in the simulator. This allowed for some really robust testing. And it was great fun to see our creation working both in the simulator and in the real world.

document - 12.71 kB - 04/25/2023 at 10:31


Atoms to Amperes.docx

We recommended some outside reading. Many of the concepts (like "hole flow" in a transistor) could not be covered in the short lecture period we had. So we recommended two books.

document - 134.43 kB - 04/25/2023 at 10:30


Instructor's Lessons Learned.docx

As is usually the case, the instructors learned too! Here are some notes on lessons learned by the instructors.

document - 16.29 kB - 04/25/2023 at 10:28


My receiver doesn't work.docx

The students must learn that new electronic projects don't always work the first time they are powered up. Here we anticipate problems that the students may face when trying to get their new homebrew receivers working.

document - 13.71 kB - 04/24/2023 at 23:38


Mods for TJ DC RX.docx

Here we encourage further experimentation and modification, going stage-by-stage.

document - 15.96 kB - 04/24/2023 at 23:36


Possible mods to TJ DC RX oscillator..docx

A possible modification to improve the tuning of the receiver. Students are encouraged to experiment and modify the receiver.

document - 15.20 kB - 04/24/2023 at 22:14


TJ DC RX Final Assembly.pptx

Here the students are shown how to integrate the four boards they have built, and how to connect a simple antenna. The students are encouraged to FINISH their project and to avoid having it end up unfinished on the dreaded SHELF OF SHAME.

presentation - 2.23 MB - 04/24/2023 at 22:07


TJ 4 AF Amplifier.pptx

The audio amplifier was the most complex board and was built last. Three common emitter AF amps. By this point students were just grabbing schematics and were quickly building the circuits using Manhattan board techniques.

presentation - 4.13 MB - 04/24/2023 at 22:01


TJ 3 Mixers.pptx

The mixer is at the heart of a direct conversion receiver. Students built their own diode rings and used transformers produced in Hyderabad India by our friend Farhan VU2ESE. This added soul to the new machine! We added a diplexer.

presentation - 2.97 MB - 04/24/2023 at 17:20



Students build a bandpass filter, and then tested and adjusted using a NanoVNA.

presentation - 1.42 MB - 04/24/2023 at 17:16


TJ DC RX 4 VFO Buffer.pptx

After the oscillator, students added a buffer using a Field Effect Transistor.

presentation - 424.36 kB - 04/24/2023 at 17:15


TJ VWS Class 1 Oscillator.pptx

Presentation for the Oscillator Build. This was the first stage that the students built. This provided very early gratification -- when the students powered up the boards, the signals could be heard in a shortwave receiver (they were LOUD!) Woo hoo -- they had made radio frequency signals.

presentation - 2.51 MB - 04/21/2023 at 10:39