Homebrew software defined radio - a demonstration

[gccengineering1996]

I have an idea, is is possible to make the variable tuning capacitor tuner a varactor tuned diode circuit and make it computer controlled?

[gccengineering1996]

Main reason why I cannot build this project because I cannot find the resonators for the 80 meter and 40 meter and how many turns is for 4.7 uh? and how many turns is for 10 uh? I would need a LCR meter to build this circuit. Also could I substitute different inductors like if I want to listen to the long wave band?

[vk3ye]

@gccengineering1996 The inductors are prewound RF chokes so no winding. No need for LCR meter. You'll need to change the local osc freq for long wave. I suggest starting with a simple direct conversion receiver (maybe a kit) and putting the audio into the computer with the SDR software.

[gccengineering1996]

@vk3ye Where do I find the prewound chokes? According to the schematic diagram on your page, it says 8 turns with a 100 pF capacitor in series with a vertical "thick line" (ferrite core) and then the 4.7 uH on the other side of the side of the line which means it's a transformer like a ferrite rod. It says it in the schematic diagram on your web page It's kinda confusing according to the schematic diagram. .

[felixragav]

@vk3ye : I have been thinking of using a cheap USB soundcard from Ebay, the ones with stereo Mic input or using the cheap Guitar to USB gadgets which have a Line In option. FB on the project. I know what Im building the coming weekend.

73

Ragav

[felixragav]

Excellent work on the RX OM. I was wondering how the mic is wired. Other 'easy' designs have 2 outputs for the Inphase and Quad signal to be fed to the line in. Am I supposed to provide the output from the mixer to both the ring and the tip jacks of the stereo plug Id be using? I'd always thought that the Mic input of soundcards are in Stereo?

73

Ragav

VU3VWR

[vk3ye]

@felixragav Ragav - my cheap laptop's only got a mono input unfortuately, so haven't had experience with the 2 output 'real' SDRs or their connections. 73, Peter

[vk3ye]

In response to the questions there are no kits. Neither are there etched circuit boards - it's quicker and more educational not to use them. But the circuit is now available on VK5TM's website. w w w . v k 5 t m . c o m

[barbosaaraujo1]

friend if you put the kit is for sale let me know and value the same 73 ok for you I really enjoyed

[barbosaaraujo1]

Hello sir I think it's easy to do this, but I want circuit diagram and pcb layout required

[tonygohil]

hello sir i think its easy to make this but i want circuit diagram and pcb layout of this one, i m from india and i m not able to get wia's ar magazin so pls send me detail to make this asap

thanks

73s

SWL Tony

[devchugani]

Brother you have the excellent brains so please keep up the good work so we can enjoy watching and listening and may be one day I'll make some thing like this.

Thanks Dev

[MassimoRosellini]

simple but excellent demonstration. '73 Massimo IW0HKG

[5ivelo]

Any news on a schematic for this?

Seems like a very reasonable entry-point to RXing

Thanks for the uploads!

[sz42781]

put you walkman back together. JK

[zappatx]

I'm new at this so pardon the elementary question but what the the general total audio bandwidth on any given setting being fed to the computers input?

[vk3ye]

@zappatx All of it. Tuning range and selectivity are determined by the bandwidth of the soundcard and the capabilities of the software.

[zappatx]

@vk3ye Wonderful! So essentially this software would be ideal for that old low selectivity but sensitive direct conversion receiver many may consider tossing away..

[vk3ye]

@zappatx Yes. It works very well for that.

[vk3ye]

@ tiputipu0052 - circuit configurations vary so it's not possible to give a straight answer. However I recommend VK2TIP's website for a good tutorial on radio circuits.

[TheHamradioguy]

Looks great...is the cct available? be a great Club Project.I'm also impressed it was able to pick up.....ME!! hih!!

Cheers

Vk3FASW

Andre

[vk3ye]

@TheHamradioguy Hi Andre - The receiver will be described in detail with two versions built. Keep an eye out for it in AR magazine.

[tiputipu0052]

if i have to make transistor radio...could you just please tell me where i have to put tank coil (emitter, base or collector) and where i have to put feedback coil??? is the areal wire you have shown with 4 turns, the same called feedback coil??? what is the function of feedback coil and where it is plased in transistor please help me...dont discuss amplifier, i want to know about the first circuit,amplification comes next stage...please help.

[yo5pdw]

were is schematic??link???

[roity57]

Nice one Peter, you even caught me calling CQ Contest during the RD! Nice demo.

[melbourneradio]

Excellent demonstration Peter

[vk3ase]

Very impressive, the variable bandwidth looks a great feature.