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Can I Replace A Crystal With A VFO In A Simple CW Transmitter ?
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- เผยแพร่เมื่อ 4 มี.ค. 2024
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I really wanted to make this work, but I do not have enough knowledge on this subject so I must learn more. This is life... sometimes successful sometimes we fail. Important is not to give up, so I will definitely return to this and make it work in a way or another, with a little help from you.
Maybe my friends Pete and Bill @soldersmoke could make a video on this sometime and help us understand why I didn't work and if us possible to make it work. I know you guys have way more experience in this than I do.
73, YO6DXE
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Behind every mistake you make, there is a great opportunity for you to learn and also for us, thank you for your videos and please keep going! 73
Thank you so much. Failing was the est and easiest way for me to learn for some reason. It makes me curious to see what was wrong... then I discover an entire little world of details I didn't now about before. Love it. 73, YO6DXE.
Calculate the reactance of components at the designed frequency, then find the L and C values at your desired frequency.
The frequency is ok... I think the transmitter circuit needs modifications in oder to work.
Try buffer transistor stage too. 73!
Right now I have one buffer and a buffer / amplifier stage too. I built the full schematic by W1FB of the VFO. Still no luck. I need to measure the output signal lever of the VFO as it is now and check if is 4 volt as described in the article. I don't really know how to measure that signal 😁. More new things to learn for me. 73, YO6DXE.
yes thanks for the video, i hope you succeed !! 73's
Thank you so much. I hope so as well. I have to )). 73, YO6DXE.
Thanks for the experimental vedio
Thank you as well for watching. 73, YO6DXE.
Very interesting video and topic !
Thank you my friend. I really want to learn more about this. Its been a while since I had this in my mind )). 73, YO6DXE.
Muy bueno!!73.
Gracias 🙏. 73, YO6DXE.
Cool thing!
Today I am "house work" free and working on a new one 😁😋🤗🤗
Haha, really enjoyed the video! Just pure experimentation and confusion. For me there is something missing between the VFO and the transmitter. It seems that connecting them directly is not the ideal solution. 73
I love experimenting especially when I don't understand things 😅. It actually helps me understand so failing is good sometimes. I think there is something on the transmitter side... since basically I am connecting an oscillator to another oscillator ... and the idea is for the last stage ( the transmitter ) to be just an amplifier. At least this is what my common sense tells me )).
@@dxexplorer I understand, maybe try removing this 120pf capacitor on the transmitter side. Also i have seen a lot of circuits that pick up the rf from the collector of the transistor. Hope it is something like , otherwise you have to add a pre amp(buffer)
@sv2tcb Yes... clearly the TX needs modifications. The VFO already has a buffer stage and a buffer / amplifier stage... it should have a good signal... I think.
Idk I’m as confused as you are at this point. So I’m gonna sit and wait for the real answer to come up. 😅
I would’ve tried to disconnect the Freq. counter. And hope the signal is now big enough to oscillate the transistor in the transmitter. 🤷🏻♂️
I did that too... most of the time I don't use the frequency counter.. still nothing though. I have a feeling there is more to this than just connecting the VFO in the spot for the crystal )).
@@dxexplorer I’m afraid it is.
I make a list of all suggestions I receive and when I get home I will try them all. The best way to learn. When it will work... everything will make sense and why I had to do something in a certain way 😁.
my suggestion is to remove C1 from the transmitter.
Thank you. Noted that down. I make a list with all suggestions and try all of them ))). It has to be something to modify on the transmitters that is what my logic tells me, I just don't have enough knowledge to figure this out )). 73, YO6DXE.
so i think it doesn't work because transmitter schematic is bit different i think it would need some changes. transmitter schematic is similar as one transistor crystal generator so it my be problem here. I will ask few people about that and give you answer
I would really appreciate that yes please. And yes basically the transmitter is a low power crystal oscillator so is like sending signal from an oscillator to another oscillator right ? )) is a bit confusing for me. Clearly there must be some changes to be done. I know in the tube transmitters there has to be a 20nF capacitor from grid to ground added extra in order for it to work... but in the case of these simple schematics with transistors... I am lost ))).
OK first of all you need to really understand what you are doing 😆 Your small transmitter is nothing else as fix frequency oscillator with output impedance tuned to antenna. And what you are trying to do is variable frequency oscillator to drive your fix frequency oscillator 😁 Silly indeed. You have to only adapt output impedance of your VFO (by transformer or add additional buffer with proper output impedance) and you can use it as a transmitter directly.
Indeed that is exactly what I wanted to do )). But the idea was simple... to use the VFO as a replacement for a crystal... for those that do not have one... and also to be able to change the frequency a little. Indeed the simple transmitter is nothing but another oscillator... but if you remember how in old tube transmitters you could "adapt" the circuit to work both with a crystal and also with a VFO with little modifications to the transmitter... and that one basically becomes more like a PA stage instead of a simple transmitter 😁. I hope it makes sense haha. That is the idea of the experiment... the learning process... ))). 73, YO6DXE.
@@dxexplorer There is only one meaningful way to tune the frequency of that small transmitter and that is to add tunable capacitor in parallel or in series with crystal. By this you will get some possibility of tuning. Because you current solution doesn't have any sense.
@bfx8185 Ahhh no no I do not want a VXO... the tuning range is way too small and is not worth the effort. I find that useless... that is why I wanted VFO. Ehhh you will get the idea of what I am trying to achieve a bit later once I finish experimenting ))).
@@dxexplorer there is only one way to get your idea working and that is transformer at the output of your VFO something like 1 : 4 impedance on the core like FT-50A-61
I tried with a T50-43 because it was all I had on hand out of curiosity... but I think I need to modify the circuit of the transmitter in order to make it work too. But I gather all the ideas that you all put me here and try them all because is fun to make these experiments. Theory is nice but when you do and see things in practice too.. working or failing... both make me understand and the see logic of things and how all works. So.. transformer on the list too 😁😁. Got to start work... have a fantastic weekend and thank you for the tips. Very much appreciated 🙏. 73, YO6DXE.