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.
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
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.
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
@@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.
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"
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
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!
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.
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
The thing I always like is how clean the audio is with DC receivers
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
Very cool!! I wish that I had your knowledge!
Very nice sounding..
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.
Nice build as usual Bill...did you mod the tuning cap by removing plates or did you get it that way? 73 - Dino KLØS
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
@@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.
Seems like you're missing a 1k resistor on the top collector which would balance out the 3.3k on the emitter.
Bill these videos are great! This is just the stuff I like to watch! 73 de Seth - W8FG
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.
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"
A block diagram would be nice, then dive in the electronics
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
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
Markus: I think the subtitles are now ON and you can also opt for translation to German. I hope this helps. 73 Bill
@@soldersmoke Thanks a lot! Works perfect!
Sir please dislay the circuit with parts details
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!