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Direct Conversion Receivers

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Bill blames Dean KK4DAS, Farhan VU2ESE, and Wes W7ZOI for this recent bout of direct conversion-ism.
This all started when Farhan included a Permeability Tuned Oscillator in his Daylight Again rig. So Dean and I built PTOs. Then we built a super simple VFO that Farhan has in another DC receiver project. I attached a variable capacitor to this. Then of course I was on the way to a DC receiver. I used an AF amplifier I had built for another project. The receiver works great.

Опубликовано:

24 авг 2024

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Комментарии : 21

@G4KDXlive 11 месяцев назад

The first HF receiver I had capable of resolving SSB was a home-brewed direct conversation receiver for 40 metres I built in the 1980s from a circuit published in Practical Wireless magazine. Hearing all those SSB stations was really exciting. .. since the I’ve always had a soft spot for direct conversion receivers.

@StephenFarthing Год назад

Another super video. I can’t wait to get back to my shack and melt some solder. Greetings from Budapest, Hungary. 73 de Steve G0XAR

@OldF1000 Год назад

The thing I always like is how clean the audio is with DC receivers

@edbeckerich3737 Год назад

Very nice sounding..

@tcarney57 Год назад

A junque-box receiver such as this will be great as a high-school teaching platform. It readily highlights the difference between function--which it does well--and mere appearance. It's a distinction that doesn't come naturally to teenagers. That VFO coil alone--looking like it was wound on a Freddie-the-Freeloader cigar stub--should convince them beauty is only skin deep, but ugly goes to the bone. --Todd K7TFC

@drstrangelove09 11 месяцев назад

Very cool!! I wish that I had your knowledge!

@TheGmr140 11 месяцев назад

A block diagram would be nice, then dive in the electronics

@johnwest7993 Год назад

I think your emitter resistor value started out too low and the current fluctuation was causing voltage instability through the zener regulator diode sufficient to make the oscillator unstable.

@PapasDino Год назад

Nice build as usual Bill...did you mod the tuning cap by removing plates or did you get it that way? 73 - Dino KLØS

@soldersmoke Год назад

Dino: I removed the other plates years ago when I was young and foolish, and before I realized that a fixed cap in series would have the same effect! 73 Bill

@radiotec76 Год назад

@@soldersmoke, ugh Bill! I feel your pain! I pulled the plates on my ARC-5 Command set VLF receiver tuning cap back in the mid 1970s foolishly thinking I could covert it to receive on 10 Meters but instead I ruined it not knowing I could tune into the IF of a commercial multi band shortwave portable receiver and pick up LSB and CW signals on 80 Meters. I found another ARC-5 and may pull its RF coils, IF coils and tuning capacitor and get it working again.

@andrewferg8737 Год назад

Seems like you're missing a 1k resistor on the top collector which would balance out the 3.3k on the emitter.

@gangadharana2467 9 месяцев назад

Sir please dislay the circuit with parts details

@soldersmoke 9 месяцев назад

All the info is here. hackaday.io/project/190327-high-schoolers-build-a-radio-receiver. You should build this receiver! Please let us know how your project goes!

@sethlavinder Год назад

Bill these videos are great! This is just the stuff I like to watch! 73 de Seth - W8FG

@chronobot2001 Год назад

You mentioned that DC receivers don't do well with AM signals. Why not? I would like to hear how AM on a DC receiver sounds.

@soldersmoke Год назад

The problem is the phase relationship between the carrier and the two sidebands. When you are demodulating with the carrier from the transmitter itself you do not have a problem. It sounds great. But with the DC receiver you are using a product detector and a local oscillator (VFO or PTO). Even if you can get that VFO or PTO exactly on the carrier frequency, you will not -- with a simple DC receiver -- be able to get the phase relationships right. Your LO is likely to be out of phase with the AM carrier. And your LO will not have the correct phase relationship with the two sidebands. All of this leads to distortion. You can understand it, but it sounds awful. This is very similar to the problem of listening to a Double Sideband Suppressed carrier signal with a Direct Conversion receiver -- you can understand it, but it sounds distorted and terrible. SSB and CW however, are detected with no problems. For more on this, and for recordings of DSB signals as heard in DC receivers, go to the SolderSmoke blog and do a blog search for "peter-parker-reviews-dsb-kit"

@markusm.lambers8893 Год назад

Please, could you enable the 'underline tiltles' ? It helps me so much to understand all the words you say. I am not a native english speaking person. - Thank you in advance. - 73 de Markus ; db9pz

@soldersmoke Год назад

Markus -- I would like to help. I tried to turn on German subtitles, but I don't know if I had success. Thanks for trying. 73 Bill

@soldersmoke Год назад

Markus: I think the subtitles are now ON and you can also opt for translation to German. I hope this helps. 73 Bill

@markusm.lambers8893 Год назад

@@soldersmoke Thanks a lot! Works perfect!