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Tuesday, May 4, 2021

Ciprian's Romanian Ten Minute Transmitter with Roots in SPRAT, KA4KXX, and the Florida Sunrise Net


It sounds great Ciprian!  It was really cool to see your video and hear you reference not only the SolderSmoke blog, but also SPRAT, the Michigan Mighty Mite, and Walter KA4KXX. Your little rig has a very fine lineage!  

I found Ciprian's video just after seeing the wonderful Herndon Mighty Mite of Jack NG2E.  TRGHS!  The Color Burst Liberation Army is on the march!   For more info on NG2E's Mighty Mite, check out his blog: https://jackhaefner.blogspot.com/2021/05/mounting-to-perfboard-and-scope-test.html 

Jack has in his possession one of the  7.123 MHz crystals that Walter KA4KXX sent me back in 2019 (during my ET-2 craze).   It seems obvious that Jack should build a Ten Minute Transmitter and use it to check into the Sunrise Net  https://qsl.net/srn/

16 comments:

  1. Thank you so much. I had to say something... a way to say thank you ) This little transmitter was fun to build and I already have some "improvements" in mind for the next one. But before that... I must build the Michigan Mighty Mite as well. Thank you one more time... 73.

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    1. Ciprian, we may be "passing streams!" I built the MMM last weekend and hope to build the 10 Minute Transmitter with low pass filter this weekend. High five we like to say....

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    2. Hahaha... that's great. I will do the MMM next weekend as today I'm working on a receiver I've been trying to improve a little and I'm almost done )) 73 and I hope your ten minutes transmitter project works well.

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  2. Dear Ciprian: Great to see your video, and please be advised that the way to tune the "240" pf series output capacitor is to first connect a 50 ohm dummy load to the transmitter and peak the RF Output Voltage. If there is no defined peak then temporarily use a variable capacitor with a wide range because your value may be much different than mine since you are using another transistor, circuit board layout, etc. Also, note that in my version I connected the transmitter to a multi-stage antenna tuner before attaching that to my end-fed antenna so my signal out of the antenna was probably very clean. I do not know your callsign so please advise, and feel free to contact me by direct email (see QRZ.com) if you have any questions.
    72, Walter KA4KXX Orlando, FL, USA

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    1. Thank you so much for all the information Walter. I noted everything and I'll put it in practice. I'm also using a half wave end fed antenna for the forty meter band with a 49:1 impedance transformer... well... for my receiver. For now I will only test the transmitter and playing with it with a dummy load. I'm still waiting for some free time for my amateur radio exam. No call sign... yet, but soon. Building all this little and simple circuits help me a lot in understanding how everything works so it helps me a lot in my learning process. Best wishes from Transylvania. I miss Orlando by the way ) 73 and have a wonderful week. Thank you one more time. I will search QRZ database and send you an email if they will let me see it. I'm registered but not with a call sign yet.

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    2. Hi Walter, I have built this really neat transmitter. Thanks for sharing your design.

      When determining the output capacitor, what do you mean finding the "defined peak?"

      Thanks,
      Jack
      NG2E

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  3. Dear Ciprian, very nice video and a good result with just a few components. You make excellent printed circuit boards too. - 72 Tony G4WIF

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    1. Thank you one more time Tony. Old school PCB with a marker hahaha. Quick and easy to make. 73 my friend and have an amazing week.

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  4. I wanted to say thank you all for all the help... turns out the little transmitter has an output power of 980mW with a 2N2222 transistor and a capacitor value of 235pF on the output. Wow.... 73 and have an amazing week.

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  5. Ciprian -- FB OM. Please do a video on your 980 mw rig. Is it an MMM or a Ten Minute Transmitter? NG2E and I are building Ten Minute TXs. 73 Bill N2CQR

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    1. Hi Bill. Is the one presented here in the article... and then I've made one more video about a 50 Ohm dummy load where I've measured the output power. I was not expecting 980mW hahaha. It's the Ten Min Transmitter yes. 73

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    2. Good demo for measuring output power! Thanks, Jack (NG2E)

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    3. Thank you Jack. Greetings from Transylvania... now it's time for an MMM ))) 73

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  6. Ciprian,
    I finally built the Ten Minute Transmitter. (Hint: it took me longer than 10 minutes).

    Made two blog posts. First for the transmitter: https://jackhaefner.blogspot.com/2021/05/moving-forward-with-40m-transmitter.html. Second, for the low pass filter: https://jackhaefner.blogspot.com/2021/05/low-pass-filter-construction.html.

    I'm going to find an enclosure and build a hasty antenna switch next so that I can share my 20m/40m parallel dipole with my KX3....

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    1. That sounds great Jack. Let me finish work and I go read the posts as soon as I get home. How cool. By the way... it seems that I didn't used the right formula to calculate the power of my transmitter. I was actually calculating only the peak power) So it only has about 500mW output at 12v. But I'm still happy with this little bugger that made my day building it hehehe. 73

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    2. Lots to be happy about with your little rig!

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