I still don't have the output stage (transistor, mic, etc) soldered, but I will remember that. Could I just connect MP3 player output instead of mic and then try to transmit signal few meters across the room?So when it is all working, you make sure no audio enters the mic input then adjust the two potentiometers for minimum (ideally zero) output.
I've added 15pF capacitor and it's working all the time now.The oscillator should run no matter where the control is set, if it is stopping it is probably at the extreme of minimum value. You could try adding a small capacitor across it to prevent the value reaching so low (~5pF) or you could try changing the transistor for one with higher gain.
When you hear a station near 3.58MHz, adjust the 'can' transformer for maximum signal. It is the equivalent of the bandpass filter on your Lidia receiver but because the tuning range is so narrow on this one, a peaking filter is more appropriate to use.
I have really no idea how are you able to tell that there is a SSB voice! I am sure that I am younger than you, but it seems that your hearing is indeed very much better!All of those are CW stations with a little SSB voice in the background on the first one. I couldn't quite read the CW but I think the second one is from an Italian station calling "CQ DX" (request for a distant contact).
You certainly need a filter but first try to understand how they work. I will explain as simply as I can:Now then, it seems that I also need to add a proper antenna filtering, right? Would it make sense now to get the rid of IF can filter and add a proper 80m signal filter?
Its very difficult to tell. There is more gain in the MC3361 so it should be more sensitive but it probably has poorer balance in the mixer. There probably wouldn't be much difference overall.Btw, if I replace the filter with bandpass one, and add a wider VFO, how good would this transceiver work (in your opinion) compared to the MC3361 one?
Yes, they are the same, I just uploaded them just in case.I can't use EAGLE files so I'm working from the images, I presume they are the same.
The "VDD" on the schematic is supposed to be regulated 8V. The regulator on the schematic is the 7805. It was that way all the time. By the way, is that 7805 needed there? I'm kinda not sure but it's the design from: https://hs8jyx.blogspot.com/2013/08/ssbcw-7-mhz-fine-tune.htmlTake the top of R2 & R15 to the regulated 8V line instead of the incoming 12V. It will slightly reduce the tuning range but you can recover that by shorting out R2 and R15 and maybe (probably not necessary) increasing the values of C12 and C14 slightly. By using the regulated voltage for the tuning supply, you remove the risk of the frequency drifting if the 12V isn't stable.
Speaking of of co-axial cables, I've been recently wondering how should I deal with antenna connections. Right now I have four simple (but working) receivers build, but I don't have any antenna cables/sockets setup. Are they standarized, or can I just RCA sockets and cables recycled from waste? I'm not even sure how are they called, are they the same as "TV aerial antenna plug"?The board connection pins are not really rated for RF signals but at 3.5/7 MHz they should be adequate. If you move the pins right up to the edge of the board you can make them reach far enough to plug directly into the other board. Remember that connecting wires between the boards are not a good choice because of the inductance they introduce. If you do intend to link the boards with wired connectors, use a screened co-axial cable for the RF output.
Sorry! My mistake - so many schematics...The "VDD" on the schematic is supposed to be regulated 8V. The regulator on the schematic is the 7805. It was that way all the time. By the way, is that 7805 needed there? I'm kinda not sure but it's the design from: **broken link removed**
They supply it being as kit.
http://www.ozqrp.com/shopDX.html
Hey, are you the one of the site authors? Do you know if it's possible to get just the CAD files of PCB?
I am considering building this radio in the future (at least receiver part for now), especially because I already have most of the components at hand. I just need PCB. With the CAD files I could etch it myself at home.
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