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Simplest transceiver - CW only (Morse)

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Simplest transceiver - CW only (Morse) Empty Simplest transceiver - CW only (Morse)

Post by admin Mon Aug 12, 2019 10:34 pm

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.

Simplest transceiver - CW only (Morse) Img_9310

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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