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Analog VFO Project For The 40m Band ( 7 MHz Variable Frequency Oscillator )
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- เผยแพร่เมื่อ 2 มี.ค. 2024
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Long time ago I was told I can replace a crystal in a CW transmitter with a VFO to adjust the frequency. I never tested that and I never built a VFO. Here is my first 7 MHz variable frequency oscillator build ( almost a fail and now I also know why ).
Special thanks to @MIKROWAVE1 for the great videos on VFO's. I am learning a lot from those and the lessons are also great for improving the stability on regen receivers too.
73, YO6DXE
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The first circuits I tried, were meant for other frequencies. After I failed I realized that I don't just have to change the LC tank for the frequency I need, but also the values of other capacitors in the oscillator. I didn't know that so I guess that is the reason the first versions didn't worked. I am still learning, but I find VFO's fascinating. No wonder I love analog technology. 73, YO6DXE.
Sounds like you learned a great lesson 👍 that's indeed what its all about afterall.
@@SimonsSolarShed yes that is so true. I was just saying this in the coming video ... sort of part two of this one.
@dxexplorer I shall look forward to your next video, I really enjoy them...the great thing about you is your just like us who like to experiment and don't act like a snob thinking you know everything lol. You know the kinda people lol
@SimonsSolarShed I wish I knew everything, but then my name would be God 😅😅😅. Ohhh I will say like grandpa... I learned all life long and I still die stupid 😅😅😅. I miss his words haha.
Классные площадки для макетирования! Киприан, это просто великолепно! Я собрал ваш Sputnik, получилось отлично, все работает, как описано, великолепный дизайн схемы, спасибо! С приемом только мучаюсь - без приличной антенны это все очень случайно и эпизодически. Начал думать насчет антенного усилителя, но опять же нужен какой-то образцовый генератор для настроек. Сейчас вот сделал первый вариант такого генератора (двухтактный, с внешним возбуждением), он уже работает, но там со стабильностью частоты не очень хорошо - она плавает в районе 2-3 килогерца туда-сюда. Сейчас вот увидел ваш VFO, и подумал - а это будет полезным, сделать такое. Кстати, я научился делать конденсаторы переменной емкости, прецизионные, из канцелярского клеящего карандаша, настройка с таким конденсатором получается очень точная, хотя ваш вариант на варикапах мне тоже понравился. 73!
Я очень рад слышать это, мой друг. Да, иногда иметь хорошую антенну непросто, особенно если живешь в городе или даже в деревне... если нет большого сада. Думаю, у меня тоже есть решение этой проблемы, ха-ха-ха. но вам придется подождать конца месяца, так как у меня сейчас нет свободного времени для работы над проектами. Я помогаю сестре и зятю построить дом. Насчет переменных конденсаторов.... сестра только что купила станок для лазерной резки, и я все время задаюсь вопросом, смогу ли я разрезать алюминиевые элементы, чтобы сделать переменные конденсаторы ))). Посмотрим. Я рад, что «Спутник» работает нормально. Приемник близок моему сердцу. Скоро поговорим... Мне пора бежать на работу. 73, YO6DXE.
I'm so excited for the final version of this transceiver
Technically I wanted a separate VFO to use for tests and so on. But you are right... I am thinking on using the same schematic to start building my first 100% homemade multiband analog transceiver ( haha ). 73, YO6DXE.
Very instructive these experiments. Nice work! Building VFO's can be challenging but I learned a lot by building simple DC-receivers. If good VFO stability is what you are after, you really should consider a PTO oscillator. For me that was a real eye opener. I rebuilt a 20m band DC receiver I once built in 1979 when I started out as a young experimenter and it worked fine except that it drifted quite a bit which I found annoying. Everyone told me that I couldn't expect a VFO to be stable at that frequency but I kept experimenting with a permiability tuned oscillator using a glue stick drive. I built this oscillator using the same circuit as before (only 1 3810 FET, no buffer) and to my amazement it was steady as a rock. If you are interested I can send you the schematic details and a photo of the oscillator.
Ohh yes please that would be great... talking about the schematic. I also received as a present some while ago some variable inductors... the drive is pretty similar to the one from the variable capacitors... with reduction drive too. So I thought one day o will put those to use 😁😁. Still lots to learn for me so I understand them well... but I am slowly getting there 😁. 73, YO6DXE.
Please post the circuit.
I built variable capacitor with two fixed, immovable plates, BUT adjusted a plastic dialectic between the plates to tune vfo.
I have example on TH-cam.
Looking forward to your design
Thank you
@kf5hcr176 I will have a look at the video. Ohh yes once I am happy with the circuit and I see that all works fine... I will post a blog article with all the details ... including the mistakes to avoid thing ))). 73, YO6DXE.
th-cam.com/video/1AEz6aEzHDE/w-d-xo.htmlsi=0e0-dOBCwdeVP7it
always interesting..., good job!
Thank you so much. Good so far... we will see next )). 73, YO6DXE.
a very good starting point... great progress...
Thank you so much. Let's see if the next step goes well or not ))). I have a bad feeling ))). 73, YO6DXE.
I think you will get it sorted out ok...
@@davidportch8837 I hope so 😁
I love this, might have a go myself inspired by your videos fantastic layout I love manhatten construction
Manhattan style is nice, especially made with patience it can turn out really great. I should also do this more often. Good luck with your project. Let me know how it goes. Just don't use the same cheap capacitors like me hahaha. 73, YO6DXE.
its nice but bit unstable. coil needs some type of box for shielding as i told you. later i will teach you how to make proper box for it. also i think you need to use diode tuning because frequency can be adjusted precisely or you should use some tipe of gear mechanism "vernier"
Ohhhh is not unstable is very unstable hahaha. But this one is just a test as I was saying in the video. The final one will be a fancy one 😁. But for now... I will keep it as it is to learn a little more about it... then build a proper one. And that cheap capacitor I used in the video... big no no for VFO for sure. Thanks so much my friend. 73, YO6DXE.
Change capacitors. To blue colors high voltage ones. It will helps quite a lot to have stable oscillator. I tested before. Very good results with that capacitors. Your next problem will be when you attache antenna. Because change anything around antenna with change frequency of oscillator. Then as my test. The only option for antenna for this type of oscillator is mag loop antenna. I think you will get some results too. 73
Ohh in the final version yes I will use good quality capacitors. Right now just for testing purposes I don't really care if is drifting or not. I want to test a few things I was told about and they were stuck in my mind to try one day. Now is the day to try haha. 73, YO6DXE.
From baghdad iraq73
73 my friend.
Thanks for your service KE4TDG. 73
Nice vedio ❤
Thank you so much. I am curious about how stable the final version will be ( ha ). 73, YO6DXE.
@@dxexplorer exactly..... waiting for that
Hi Ciprian, where do you get these little square experimental soldering pads?
73 de Bernd - DF7PI
Ebay sells these pads you could actually cut some yourself out of copper clad 😀
The ones in the video I had them from my friend Andrei, YO6TJJ. Usually I get them from here: www.kanga-products.co.uk/ourshop/prod_7633806-Manhattan-Style-Solder-Pads-sheet-of-150-Double-Sided-Pads.html
73, YO6DXE.
This too also yes )) I used to cut mine as well for a long time. 73, YO6DXE.
@@dxexplorer that's what I wanted to know. You have helped me a lot. Thanks for the Link. 73 de Bernd
@@berndb.5097 Always a pleasure my friend. I will also have to order a batch as I will run out soon haha. I will try to see if I can actually order them directly from PCBWay when I order PCB boards 😋😁.
Ez választ adott egy kérdésre, hogy az 7 Mhz-ből magasabb frekvenciájú jelet is ki lehet nyerni.
A kristály oszcilátornál én egy IC foglalatot használok, tudom javasolni.
Azt hiszem, a Google nem fordított olyan jól, de azt hiszem, értem, mire gondoltál. Igen, ha akarod, kérlek küldj egy emailt. Bocsánat a magyar barátaim csak rossz szavakra gondoltak magyarul hahaha. 73, YO6DXE.
@@dxexplorer Meglehet hogy a Google a barátod, de a Magyar nyelvtan olykor még nem megy neki. De azért már rendkívül sokat fejlődött. További szép napot vagy estét, és tiszta vételt 73.
@@MrTauron77 Nagyon szépen köszönjük. Na igen, ez így van, de románul is, ha más nyelvről fordítok, általában sokszor vicces lesz a szöveg. De legalább képet kapunk arról, hogy miről beszélünk))). 73 és szép hétvégét... van még egy kis.
Hi Ciprian, I am curios about the frequency you are using? do you have a link to it so I can get one ?
I have a feeling you meant frequency counter 😁 ? I didn't buy it as it was a present from my buddy ZL1NAY, but I will leave a link as I have found one that I want to buy to have a few at hand for diferent other projects as I really like how it works. I think is a slightly different version but it should do the job just the same.
www.aliexpress.com/item/1005005992460293.html
73, YO6DXE
@@dxexplorer thanks for your reply, yes that is what I meant, I found one that look like it in AMZON but not so good reviews ( Acxico Frequency Counter )
@noelrodriguez Is possible... I know some are ok some not so much. I want to order one and test it... and if I am happy then I order more. For these simple receivers I don't really need 100% precision... at least I know where I am in the band. Probably for a transceiver I would make sure is precise though.
@@dxexplorer yes, I will order one and do some testing, I don't have one and is difficult to know what frequency I am hitting or if my coils are within the band. I do like the way you used the nanoVNA the get the inductance value (in one of your other videos). Using the Smith chart to see the value at 50 ohms at the frequency you need. I guess we can use the same to get the value of the cap at the same frequency and get a pretty good idea of the expected resonance.. great videos I am learning alot from them.
73 / W4NRI
@noelrodriguez I also need to get better with the nanoVNA as I always do things in a rush and is not good. Sometimes I get wrong values readings so I end up wasting time until I get them right hehe. I must chill a bit and study it more to fully understand the potential it had, as it can do lots of things. 73, YO6DXE
You said a simple vfo. 😅
Yep... that is what I thought too 😅😅😅. There are simple ones also... but I don't know how good they are in frequency stability. I will try one of those too so I can compare. 😁
vy nice de HL1KKC
Thank you so much Choi. Have a fantastic rest of the week. I need to catch up with your videos. Maybe this weekend I have some free time to enjoy them 😁. 73, YO6DXE.
@@dxexplorer vy tks de HL1KKC