Hobby and Fun

Description: Two air variable capacitors and a copper-clad board are mounted on a wooden base for experimental purposes. Regenerative receivers are appreciated by many builders, some of whom take them very seriously. While this respect is acknowledged, a preference for simplicity is expressed. The goal is to create a two-stage "generator" receiver, presenting two different designs: one original and another based on a JFET variant of a popular W7ZOI circuit. According to Wes, W7ZOI, "feedback your imagination." Some builders enhance the input with a simple common gate or common base RF preamp to increase gain and minimize antenna radiation from the RF oscillator, while others use an RF gain control, typically a potentiometer, to prevent overloading the RF stage. The decision on circuit design is left to the individual builder. Numerous examples of regenerative receivers are available online, with particularly intriguing designs emerging from Russian-speaking experimenters.

An experimental, ultra-simple "CW" receiver operates at 5339 KHz, receiving strong Morse code signals, possibly from China. This receiver is connected to a 1/4 wave 40M band vertical antenna, with a simple matching network and a trimmer tuning capacitor at the input. The receiver produces a pleasant beat note, functioning without regeneration control and fixed for CW operation. Minimalist circuits are entertaining; however, some dedicated regenerative builders may be concerned about the absence of a voltage regulator (a version with a T68-6 inductor exists) and regeneration control, along with a relatively low Q coil. The design process aims to create a unique receiver rather than merely replicate existing designs, leading to the creation of the "Stupid-Simple" receiver. Despite its crisp and warm audio output, some bench work is necessary to achieve the correct bias and the appropriate amount of positive RF feedback, making it an experimental circuit suitable for collaborative projects, such as those between a parent and child. More circuits of this nature are desired.

The "Stupid-Simple" experimental receiver is set up for approximately 6 - 7 MHz. The year 2011 marks the 50th anniversary of Radio Habana Cuba, with tuning to RHC at 6010 KHz being a long-standing practice for shortwave radio enthusiasts. Three audio recordings from around 6 MHz were made between 2:30-2:40 GMT on February 28, 2011, including a fading episode of DX'ers Unlimited by Arnie Coro. The audio stage for these recordings was a discrete transistor AF amplifier designed by the builder, although an LM386 was ultimately chosen for the final amplifier to simplify construction. The receiver's breadboard setup for 6 MHz is illustrated, featuring the T68-6 transformer, where the red secondary windings are wound in the same direction as the 22 turns of the primary. The builder began with nine turns and unwound links, testing sequentially until the desired feedback for AM was achieved. Standard hookup wire was used for the secondary winding, and the white cable connects to the audio amplifier. This prototype experimental layout emphasizes that a regenerative receiver should have short connections around the tank circuit and ideally be housed in a metal enclosure for optimal performance. In some instances, the simple 1 RF + 1 AF stage receiver outperformed a superheterodyne receiver.Above ” 2 air variable capacitors and a copper clad board screwed onto a piece of wood for my bench musing. Regenerative receivers delight and amaze ” some builders take them very seriously. I respect this, but to me; they should be as simple as possible. I wanted a 2 stage "genny" receiver for this page and present 2 different receivers; 1 is my design, the others is a JFET

variant of a favorite W7ZOI circuit. Quoting Wes, W7ZOI "feedback your imagination". Some builders place a simple common gate or a common base RF preamp on the input to boost gain and reduce antenna radiation of the RF oscillator, while others place an RF gain control on the input ” usually a potentiometer; to prevent overloading the RF stage. I won`t prescribe what to do ” that`s up to you. There are countless example of regenerative receivers on the web and you can many spend hours viewing them.

Some of the most intriguing are those built by Russian speaking experimenters. Example link. Above ” An experimental, ultra-simple "CW" receiver. At 5339 KHz I hear strong Morse code each night. It`s suggested to be from China, but I`m unsure. Connected to my 1/4 wave 40M band vertical - a simple matching network and trimmer tuning capacitor were fitted to the input. Here`s some audio. I like the beat note of this receiver - it has no regeneration control and is fixed for CW. Minimalist circuits are fun ” some hardcore regen builders might freak out; no voltage regulator (here`s a version with that + a T68-6 inductor), no regeneration control (here`s a version with that), a relatively low Q coil etc.

I wanted to try my hand at design and not just copy someone else`s receiver. I call it the Stupid ”Simple receiver and although it emits crisp, warm audio, some bench work is required to get the correct bias and appropriate amount of positive RF feedback ” an experimenter`s circuit that explores DC bias and AC feedback. The sort of thing a father can build with his son. We need more circuits fitting this profile. Above ” The Stupid ”Simple experimental receiver set up for ~6 - 7 MHz. 2011 marks the 50th anniversary of Radio Habana Cuba. We tune RHC at 6010 KHz, and as long as I`ve been listening to SW radio, I`ve tuned this station. Here are 3 sound bytes from around 6 MHz recorded from 2:30-2:40 GMT on Feb 28, 2011, including an old repeated episode of DX`ers Unlimited by Arnie Coro which had faded out by the time I located and turned on my audio recorder.

Audio1 Audio2 Audio 3. The audio stage in these recording was a discrete transistor AF amp I designed, however, an LM386 was chosen for the final amp to keep the parts count and difficulty down. I got a little too close to the receiver a couple of times during the recording and made the open circuit breadboard squeal.

Above ” The Stupid-Simple regenerative receiver breadboard for 6 MHz. You can see the T68-6 ” the red secondary windings are wound in the same direction as the 22 turns of primary. I started with 9 turns and unwound a link and tested sequentially until I had the right amount of feedback for AM.

I just used normal hook up wire for the secondary winding. The white colored cable goes to the audio amp. This is a prototype experimental layout ” a regenerative receiver should have short connections around the tank circuit and be in metal box for best results. On some stations, my little 1 RF + 1 AF stage receiver sounded better than my superheterodyne receiv