AM Radio - Part 2a Franklin Oscillator

Рет қаралды 3,543

Charlie Morris ZL2CTM

Ай бұрын

Video looking at the Franklin Oscillator.
Details on the blog at: zl2ctm.blogspot.com/

Пікірлер: 26

@BalticLab 28 күн бұрын

Man, you can't do that to me, I was about to go to sleep, now I just have to watch this video! 🙂

@CharlieMorrisZL2CTM 27 күн бұрын

Ha ha. Sorry about that!

@BalticLab 27 күн бұрын

@@CharlieMorrisZL2CTM You're forgiven, it was worth the sleep deprivation 😀

@thomaskallmyr 22 күн бұрын

November 1971 såg vi ett enormt gyllene UFO,klockan 20.04 till 20.13 Tidsmaskin uppenbarade sig vid Nötesundsbron,Vindön,Sundsandvik,Orust,Bohuslän,Sverige 440 meter i diameter,svävande tyst och blickstilla 50 meter ovanför havsytan toppen syntes ovanför Vindön som är 87 meter över havet.Farkosten for 20.13 blixtsnabbt österut,helt ljudlöst,5 till 6 ljusblixtar,sedan ett LASER rubinrött 200 meter stort virvlande gnistrande lysande moln....en mörkblå NATO stjärna långt bort ovanför Uddevalla,Bohuslän,Sverige. Det vart en Lördagskväll i November 1971 och UFOt hördes på Bert Kjelldahls Bilstereo,men inte i hoovrande,eller när den ljudlöst for iväg.

@thomaskallmyr 22 күн бұрын

@Alamartec 24 күн бұрын

Great series, I am looking forward to the mixer stage.Best of luck.

@CharlieMorrisZL2CTM 23 күн бұрын

Thanks. I'll be using a SBL-1 as I have one of those in the junk box.

@mbunds 19 күн бұрын

It has become my sole task to learn to write and draw as neatly as you do.

@CharlieMorrisZL2CTM 18 күн бұрын

Still bit of a scribble. I enjoy the pencil.

@agush8082 27 күн бұрын

great project i like the way you made a prototype ..

@CharlieMorrisZL2CTM 26 күн бұрын

I find using the stripboard upside down works well for me at the frequencies I play with.

@GTS00000 27 күн бұрын

Fantastic! Happy you are back mate

@CharlieMorrisZL2CTM 27 күн бұрын

Thanks. Great to melt some more solder.

@skylabby 27 күн бұрын

Enjoying this series.

@CharlieMorrisZL2CTM 26 күн бұрын

Thanks. Just me having fun melting solder. Not a 'this is how to do it'!

@nickgeorgie9510 28 күн бұрын

That is a gorgeous capacitor! I'm jealous! I wish I had that capacitor hehe.

@CharlieMorrisZL2CTM 27 күн бұрын

Agreed. It's a nice one.

@TheEmbeddedHobbyist 27 күн бұрын

I expect in the old days they could just wrap the dial cord in the other direction to suit the knob rotation.

@CharlieMorrisZL2CTM 26 күн бұрын

I must admit I don't have any experience in those old radio, but that does make sense.

@dayleedwards3521 27 күн бұрын

I dont understand the need for such a high IF? At BC freqs, with a standard 455kc IF filter, images are easily 50dB down, and using a tuned RF stage, even more. The tracking issue is going to be very much worse, the Rf stages tune a ratio of 3:1, the Osc range is miniscule in comparison, making single knob tuning with reasonable tracking very unlikely. Stability in the VFO will also be an issue given the ripple in these cheap filters giving annoying phase distortion audio artifacts throughout the passband as the freq drifts... There too is the possibility of powerful signals in the 25 meter band mixing with your Osc, giving spurs in the AM band despite the balanced mixer, and front end filtering.. The mechanics of superhet AM radios is well developed over almost a century, they work well the way they are.. I am not seeing the logic in this.

@bazzaar1869 27 күн бұрын

One of the advantages of high IF frequencies is the opportunity to dispense with tuned RF stages and remove the tracking problem completely, you can implement a simple lowpass filter at a frequency just above the RF range you are covering and all imaging is filtered, probably 60dB or more.

@johnnorton6085 27 күн бұрын

As I understand it Charlie is using junk box parts. He simply wanted to use that gorgeous variable capacitor. I have the same 9Mhz crystal filter and I wanted to use this as a spring board to a general coverage receiver. It's all good fun.

@CharlieMorrisZL2CTM 26 күн бұрын

Exactly. None of these videos are 'this is how you do it.' It's purely me just having fun using what I have at hand. Hopefully, it will encourage others to give homebrew a go.

@CharlieMorrisZL2CTM 26 күн бұрын

Yes, that's what I'm looking to do. I'm just using what I have at hand and not trying to reinvent the wheel, or in this case the superhet.

@4youian 26 күн бұрын

My FTDX10 has an IF of 9MHz and works perfectly tuning to the AM broadcast band. The reason for the low IF in the early days is because it was much easier to create LC filters with the required bandwidth. The other reasons for not using a low IF have already been proven false. I'm sure this will work fine and I'm excited to follow along. Cheers, Ian