Simplest transceiver - CW only (Morse)
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Simplest transceiver - CW only (Morse)
Hi all,
A while ago there was a thread discussing the simplest transciever possible. There were many designs put forth, but I have attempted to rack my brain for the actual circuit diagram.
As I remember it:
1 - The transceiver was on the Medium Waveband
2 - It could receive ordinary AM radio stations since it was a TRF design
3 - it had regeneration that made it sensitive plus possible to copy CW
4 - Powered by a 9v battery
5 - Used HiZ (crystal) or 2000Ω headphones
I do remember the physical layout "pattern" of the circuit. Now I am pretty sure it looked something like this. Component values are calculated for Si transistor, but the original used AF117 or OC45.
The diode detector can be removed if CW only is required, connect the headphones to the 1μf capacitor and a 1nf across the headphones.
The morse key increases the gain of the transistor stage, making the regenerative receiver oscillate heavily.
The circuit was more or less a childs toy to stimulate interest for radio communications, but using loopstick (ferrite rod) antennas ripped out of transistor radios. I do remember that the article used a 6" (15cm) long ferrite rod and I had a POTS telephone headphone under my pillow, listening to Radio Luxemburg every night.
This circuit is about the best I come up with from my memories. It is identical or very close to the original.
Best regards from Harry - EA/SM0VPO
A while ago there was a thread discussing the simplest transciever possible. There were many designs put forth, but I have attempted to rack my brain for the actual circuit diagram.
As I remember it:
1 - The transceiver was on the Medium Waveband
2 - It could receive ordinary AM radio stations since it was a TRF design
3 - it had regeneration that made it sensitive plus possible to copy CW
4 - Powered by a 9v battery
5 - Used HiZ (crystal) or 2000Ω headphones
I do remember the physical layout "pattern" of the circuit. Now I am pretty sure it looked something like this. Component values are calculated for Si transistor, but the original used AF117 or OC45.
The diode detector can be removed if CW only is required, connect the headphones to the 1μf capacitor and a 1nf across the headphones.
The morse key increases the gain of the transistor stage, making the regenerative receiver oscillate heavily.
The circuit was more or less a childs toy to stimulate interest for radio communications, but using loopstick (ferrite rod) antennas ripped out of transistor radios. I do remember that the article used a 6" (15cm) long ferrite rod and I had a POTS telephone headphone under my pillow, listening to Radio Luxemburg every night.
This circuit is about the best I come up with from my memories. It is identical or very close to the original.
Best regards from Harry - EA/SM0VPO
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