Regen receiver

Hi Andrew,
I am a lot better now. I spent yesterday morning at Karolinska hospital for another procedure and to be honest they made a real mess of my arm where they stuck in the tubes. But today it just looks like a heap of bruises. Anyone looking at me in short-sleeves will think I am probably on drugs or something.

As regards the receiver, like you I also favour analogue metering, and for me that is one of the big benefits of my portable FT-840 - all the benefits of a fast setup, small, stable and a good meter. I use it a lot when I am playing with antennas. I have been making up a new set of ground radials since I have had problems trying to load up on 18MHz.

As regards varicap diodes, I am not sure what capacitance range you are needing, but I found that decent diodes are hard to come by. So I now use a load of 16V Zener diodes. I was very surprised at the wide capacitance range they have. I cannot remember off-hand what exact range I measured, but it was somewhere in the range of 10pf to 20pf, and the Q was quite good. If you have any Zeners kicking around then it might be a good idea to try a couple in parallel.

Anyway, hafta go now. Catch you later, and good luck with the project.

Best regards Harry - SM0VPO

Admin wrote:Hi Andrew,
That looks like a really interesting receiver. I had a good look at it, and I do not think that the few words of French are particularly complicated. I would be interested to hear how you get on with that project.

The circuit diagram is easy to follow, but there is a 1µF across the output, and that seems a bit big (reactance = about 80Ω at 2KHz).

I once made a nice receiver using nothing more than a high-gain audio amplifier with my bench signal-generator (great stability) and a diode mixer. But this circuit with the cascode amplifier looks promising.

Hi there, Harry, hope you're better !!

As for the regen, not sure I'll go on and build it, just ... found the design an interesting one and thought to post it here; I like the buffer/preamp idea which avoids "loading" the tank circuit, and the use of varactor tunng (air vars are still around but aren't easy to find nor cheap nowadays), then if I'd ever build it, I think I'd add a "fine tune" pot and change the audio stage so that it could drive a regular speaker and not just an high impedance headphone, also, I like the idea of using an analog meter as the tuning scale, it's a smart idea in my opinion

Hi Andrew,
That looks like a really interesting receiver. I had a good look at it, and I do not think that the few words of French are particularly complicated. I would be interested to hear how you get on with that project.

The circuit diagram is easy to follow, but there is a 1µF across the output, and that seems a bit big (reactance = about 80Ω at 2KHz).

I once made a nice receiver using nothing more than a high-gain audio amplifier with my bench signal-generator (great stability) and a diode mixer. But this circuit with the cascode amplifier looks promising.

Best regards from Harry - SM0VPO

Nothing really special, but the structure of the rx is almost exactly the one I like. so I believe it may be worth a note

https://www.oernst.org/hamradio/rx/RX-2019/Rx-2019-p.html

it's in French, but the goog will easily translate it; what I really like is that the designer understood tye need for a buffer/amplifier stage between the antenna and the resonant stage... then ok the buffer may be a tuned stage too (hint - preselector) yet tye overal idea is a good one