33 - All Analog Direct Conversion Receiver

Nick M0NTV discusses and tests an all analog (and all discrete) Direct Conversion Receiver - with a Glue Stick PTO. Includes on air testing - with some seriously surprising results!

My video on building a bandpass filter is here:

Pete's J310 Product Detector is here:

My own redrawn schematic is here:

My redrawing of Dieter's General Purpose Audio Amp is here:

Farhan's Daylight Again transceiver is here:

My cropped version of just the PTO is here:

Enjoy and keep experimenting!

[gibbywankenobi]

Great Video! It inspired me to try the glue stick PTO. I built mine with a unknown core off of an old computer motherboard. Its white whatever that means. Not knowing the manufacturer it probably means nothing. It fit perfectly. I didn't even use glue it just press fit in. I used wire off an inductor from an old satellite receiver power supply. I had built a circuit to test crystals using a transistor off of an old dishwasher control board. I plugged the glue stick in place of the crystal along with a capacitor. My ancient frequency counter read I was around 9 MHz. I cheated and used a program to calculate the inductance and capacitance I needed. After taking a turn off the coil and changing the cap I can tune most of the 40 Meter band. I was amazed at how good it worked once warm. I want to build Farhans circuit next but getting started with this was lot of fun!

[acestudioscouk-Ace-GACE]

Good to see what can still be achieved with discrete components. The glue stick stability is impressive too, bet that was a pleasant surprise.

[oasntet]

When I finally got my license two months ago, I decided I'd try to DIY as much as possible, rather than plunking down $3k (on the low end!) on an HF shack. I just put together a (tr)uSDX, which is basically the arduino radio you're talking about in kit form, but I've also been watching your Daylight Again series when I have time.

Let me back up; at the start of the pandemic, I stumbled across a diy synthesizer channel (Moritz Klein) who does very low-level, explain-every-component synthesizer modules. It's far more gratifying to put together something from scratch when you understand what all of the bits do, and I've been doing just that for a while now. I bring this up because that phrase "the go of it" reminded me of that clear distinction between kits and homebrew.

Anyway, I'll likely have my Extra this weekend (going there straight from Tech after much studying) and while I'm sure the (tr)uSDX will be great for QRPing while mobile, I'd really like a receiver that I grok fully, and digital just isn't going to be that, yet. So thanks for all of these videos; hopefully between them and the other resources, I'll be able to build a receiver I actually understand, down to each individual component.

[alanmacdonald]

Cracking job mate, I've been waiting for this one since beer night last week!

[JayJay-kimi]

Great video, but I've been looking for a while on a video that explains what the discrete components are doing together and why. I owned a 130W FM transmitter when I was a teenager and was always very surprised by its internals. It was DIY, but very stable and good. Eventually I'll recreate it but I'm still in the learning stages. I know this is a receiver, so I'm starting with understanding how these work first.

[Paul_VKHN]

Never thought a glue stick could be so useful! Well done on all points, it's working a treat. And stable enough for FT8? Excellent stability Nick. 73 and looking forward to next episode.

[tdumnxy]

Impressive. Many thanks for sharing your work and knowledge.

[jonhoyles]

thanks again nick for a educational and enjoyable watch will defo have bash nice little project

[TheFretman]

I built the J310 product detector from your redrawn schematic and there's virtually no input from the RF (antenna). I don't believe it's the transformer. Have you known J310's to be bad? I ordered the batch I have from China. It's not the audio section. If I inject only a 1000hz signal at the LO input, the tone is very loud at the speaker end. Injecting the same signal only into the RF input, the tone is barely audible. The sine wave from the VFO at the 20t side of the transformer is very large, compared to the input. So I think the transformer is doing it's job. Any tips on troubleshooting?

[migalito]

Cool beans.
Actually, if I can ever get past my other retirement projects I am going to in 4 stages and over several months build SolderSmoke's direct conversion receiver that Bill, Pete & others developed for high school students.

I really want to pull this off. I've built electronic odds & ends and one very sucsessful Regenerative Receiver 12 years ago but by no means am I an EE but I think it is well worth the effort.

[BShocked]

It sounds great! What determines the bandwidth of the signal? I heard a few stations at once when you tuned to someone.

[technishn]

Permeability tuned VFO, BFO, ATU. Remember seeing an RF sig gen with sweep generator. Stood back and the dial moved by itself. Suppose you could use a motor to drive the PTO.. Lol

[andye]

Well done! (Especially the FT8.

Andy

[michaelrogers]

I really like your videos. Thanks for the time and effort you spend making them. 73 N4MJR

[hobbyrob]

I didn't understand much at first, what will be built now?
but now believe it is something with RX and TX???

[Yunesieh]

i can't believe that stability, I also made many hf oscillators, but none of them enough stable to use in real world :( . good job. 73

[jamesmoffat]

Spreading out the turns on the glue stick might slow down the tuning rate.

[deathstalker]

But which frequency receiving cw, am, fm ??? Show full circuit diagram with rf amplifier and local oscillator and mention whicn his carrier frequency

[BabylonLurker]

Glue stick inductor. I chuckled when I heard it, and I love the idea.
Another idea for a simple variable oscillator is using a ceramic resonator and a variable capacitor. Take a look at what VK3YE has done with that, you might like it
73 de OZ9QV

[markusm.lambers]

Dear Nick,

could you please 'switch on' the sub-titles? Then I can 'translate' them to my 'mother-language' and will understand some things, I will miss, when only hear the 'english comment' !

English is not my native tounge, so please help the 'not so good educated' simple people, ... outside the UK, the USA, or even Australia, ... to learn a little bit more, ... !

73 es merry X-mas to you, and all your beloved around you,
de Markus ; db9pz