#228 

Got plenty of those crystals, for sure. Also plenty at four times the frequency at 14.31818 MHz, which was used in all sorts of stuff. Dividing it by 4 gets you back to the colorburst frequency (and from there all NTSC TV frequencies), dividing it by 3 gets you 4.77 MHz, the clock rate of the original IBM PC. :-)

Nice Video, really enjoyed the frequency analysis and cleanup.

Yet another awesome video. Great presentation. Thanks, Alan.

Fascinating video, and near-perfect CW just using your index finger is a sight to see!

WOW, I haven't seen that in decades. My old junk BOXES of spare parts to make such things I lost in Oct, 2006 due to an apartment fire upstairs. That open tuning cap brings back memories.

Awsome. My. First real. Trans build. Thx. Alot.

I love videos like this. It's nice to see the practical application of test equipment. Thanks for taking the time to make this Alan 73 NE5U

Great video! I really enjoyed the explanation and looking at the attenuation of the second harmonic. Thanks for the reference links. :)

Thank you for telling us all of those different websites and blogs to go check out! ))))

Great video! Practical and instructive. Thanks!

Clearly explained and useful for me as a beginner. Thank-you.

Very interesting and ingenious! Thanks for sharing this!

Superb video as always Alan, with all informations provide to us. The tube for air coil is PVC; Kostas

Very Instructive, I built the same MMM but now I can work on a filter for it! Cheers and 73.

Hi Allan, Always enjoy your well thought out videos with labs to back up the theory.. Just like my EE classes years ago without the grouchy professors. Hi.. 73, Glenn WA4AOS

I usually do not comment, but this project got my attention. Remember: Size is not only impressive - it is practical with radio transmitter circuits. That transistor is dissipating power, possibly 100 mW! I suggest a cabinet of no less than 5 cubic feet. Alan is probably looking for a blower, in fact. A 1 inch Red Jeweled lamp, a large meter and a 4 inch dial dress out any project.

Really great video as always Alan. I sure love to get me a more modern SA one day.

Your morse code skills are mighty good!

Great work on your video I enjoy your videos keep up the great work

I came from a test and measurement background. Wish i could afford equipment like that. But glad someone has access to it and can show us these issues and show how to solve them. At least makes us aware so we don't end up on the air and get fussed at. - KM4OLT

When I worked at SiTime Corp I had a lot of measurement instruments too. But I hadn't a lot of free time to do the same videos)) Thank you, excellent video explanation! UR7WKH, 73!

First class lecture right there folks.

Alan, come on! Make a QSO with it and show it to us! Regards, Charlie.

great video , thank you for this record / 73!

Great presentation. Thank you sir!

Thanks Alan.

Cool project!

Freakin SPECTACULAR! Thank-you for that learning experience! 73 de K9SPY

Wonderful practical thank you

great video

Really enjoyed that one. Always read about filters in the ARRL handbook, but never saw it actually examined outside of simulations. Nice to see a filter in operation. Any thoughts or ideas on an external tracking generator for us poor folks who own a basic SA?

Very interesting! Thanks!

Excellent!

Thank you!

Haha, way to keep the suspense going by showing the FFT first and the time domain second.

Fugly is right! But generally I define the F part a little differently. :) Thanks for another great video Alan.

VERY nice!

I miss these types of videos from you.

Awesome.

NICE VIDEO

Brilliant

Great story! I may just have to build one of them! Sure wish he gave instructions on where to find the coil instructions. Just a vague reference to unstated web sites. I will try to hunt that. IF you use a PI NETWORK instead of LINK coupling then it won't be "dirty." I only ever used PI network. There is no need to go back to the 1930s and link coupling!

Great video and channel, thanks. If this sort of thing was around when I was at university, I might be a bit more useful now. What are the square black pads on the board that the components are soldered to?

very interesting thanks - for qrp, say 1 or 2 watts does it matter if you have those harmonics - in reality will it create interference at such low power? cheers

Interesting - must be great to have the lab toys.Thanks,Gene K1AVE

Question ... how about a clean transmitter ? fun stuff

Fun in the lab and shack. W4GSM

Great video as always dear sir. Along with the filter, if you put the signal from this one transistor receiver; who long it will travel and will be received on ordinary shot wave radio receiver?

What is the name of that particular way of soldering that you're using?.. are you using a one sided copper clad board and cut up square pieces to solder your circuit together?

Can i ask why you used an iron toroid and not ferrite , is it because this puts out some decent power and the ferrite would saturate too quickly?

alright, subscribed.

Surely you can't just put the LPF on the antenna winding of the tank coil? The joy of this and similar transmitters is to just attach a random wire to the output link circuit, and once tuned should give about 20dB attenuation of harmonics. (Not really enough, but this is only a few watts.) So how do you match the 50 ohm LPF to the output tank and then back to the random wire?

Hi, Great video tutorial. When you quote the reduction in harmonics, is your quoted figure not 10db too much due to the 10db pad still being in circuit? Meaning the quoted figures should be 25db down for the 2nd harmonic and 30 db down for the 3rd. Or did I miss something with the 10db pad still being in line while measuring the RF output of the transmitter via the LP filter? Regards, Kay UU

My immediate thought is to "clean up" the oscillator design a bit first and get it putting out a cleaner sine wave. I know easy to say. And maybe not the point of the video at all! I expect an oscillator circuit with a crystal to be able to put out a cleaner waveform than that. Maybe I need to get some hands-on time since it's been since High School since I have worked on this stuff! So many cool things to play with in life and deciding which ones to spend time on. Really enjoyed the video! Steve N8LBV Roughly how much _clean output power do you get from that arrangement? Thanks I'm curious.

جزاك الله خيرا

Filter did a mighty job of cleaning the waveform.Liked your scope, what scope would you recommend generally?

I should of built the filters... I've built 5 different Mighty Mights awhile back

one more toroidal inductor and capacitor on the filter and careful tweaking the band stop frequency and that 2nd harmonic could easily be over 20dB lower

Neat!

Hi Alan, What are you using for pads for the components? They look really nice and square! I've got a lot of copper clad, but I don't know what to do with them aside from going through a whole process of etching.

Alan thanks for another great video. How effective would it be in reducing harmonic content to change the biasing of the oscillating transistor?

Nice

Hey I just built one of these for 80 meters. I even made the low pass filter and it works great! I have a question though. Am I supposed to be able to tune this up and down the 80 meter band, or does it only oscillate at the crystal frequency? If you can't tune the frequency, what is the capacitor for?

Looking at the RF waveform in the time domain, it looks like the oscillator has some kind of "bias kink". Or is that "crossover looking" distortion caused by the crystal going through series and parallel resonance? In short, could some sort of bias changes or perhaps capacitive loading on the crystal clean up the RF spectrum of this oscillator?

Nice video as always, Alan. For the LPF, what sort of bracket did you use to mount and solder the BNC connectors to the PCB? I've always found this to be a bit of a challenge.

Cool

I didn't even know my scope had FFT on it. :) Thanks for the video.

No chirp, a nice note, this is awesome! About how many mW output is it?

Another great video. That low pass filter is very interesting. How much filtering would you get with just a single capacitor as a low pass filter. I know that a single capacitor will not be as good. But I don't know why to be honest?

RF is not my thing, but would it not be cheaper and easier to have a better xmitter to start with?

I have a quick question. So I built it in the past.. is in some of my older videos. But I had nothing to measure the LPF with. So I'm working on it again now. I made a LPF that cuts both the first and second harmonics to nearly -40dB. The issue is that when I connect the filter to the transmitter and do measurements again... the filter does not perform the same. I built the coil as in the original design. I assume that the output impedance of the coil may not be exactly 50 Ohm and that may cause the filter to react differently ? Sadly I have no osciloscope to be able to measure the transmitter while working. I just measure the LPF with the nanoVNA. All I have ( ha ). I just wonder what could I adjust to get it to perform well... at least in theory doing the measurements with the nanoVNA. Thank you so much. I built the 40m version and is good fun and great little project. 73 DE YO6DXE.

I often see inductors around 8uH in between the output stage and the antenna on most R/C transmitters, could this also be filtering, or is it impedance controlling ? Honestly to me adding an inductor there seemed a bit counter-intuitive since it would block the HF content.

Newbie question: I'm intrigued by the construction.... All the components that have ground connections are soldered direct to the copper board? For junctions that aren't at ground... how did you make the islands?

Sorry hit button before thought ended. Question was if the spectrum analyzer did not have a tracking generator. What is the work around. Thanks

Nice video. Why is it good practice to present a 50Ω load to the TG? Is it bad to run the TG open (or shorted)?

Can you tell me why its always just a lowpass filter on the outputs typically? Dont they also produce lower frequency harmonics too? So you would want a bandpass?

How do you fix the components on the copper clad? What is that technique called? Awesome video by the way!

👍Thank you sir. sir can we adjust transistor base bias,tank tuning,feedback level etc.to improve the quality of sine wave instead of low pass filter. (or introducing low pass filter after pure sine wave).

could I use a chip to modulate voice for this circuit? also how do you think such a circuit might lend it's self to vlc frequencies say below 300khz. forgive my ignorance I'm not a ham just an amateur radio builder. I've got several old radios with long wave capabilities ,but of course in the u.s. nothing to listen to but beacons lol. I thought I might build a lw transmitter just to listen to around here. awesome video

I love this dead bug soldering. Can I ask you another question on the bottom plate. Is that all the common ground? Does this help with cutting down noise etc. Does it cut out interference with ground loops etc. The thing is I use a 3M breadboard and when I build amps or anything like this I just get tons of noise and oscillations all the time. Does this dead bug style with that large ground plane help with that? Really hope so as I'll try it if so. I notice you build lots of circuits this way. Is this why you do it?

Hi Alan thank you yes i think i would like to put a crystal filter on it and may do so it looks to be a great little circuit for checking filters hi hi VK4JDJ

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Uhmm.... Question Why does the 5th and 6th harminic seam to be going up on my display ? thx

🎖🌟🎖

Those soldering islands never saw them before. Where can I get them and how are they called? I cannot see how they are connected underneath to the board the are on.

W2AEW DE NY2RF: you mentioned several times tweaking the filter. Can you explain in greater detail what tweaking involves? adjusting the spacing of turns on the toroid? Something else. Thanks, and 73, Tom

Hi allen, This is a carrier wave transmitter right ?. When you press the key a burst of carrier waves are sent out (There is no modulation involved).So What causes the beep sound in the receiver ?

+w2aew Great demonstration video, Alan. Where do you buy the board components from ? Thanks

Really great video. Can you elaborate on the use of pads? I am building a spectrum analyzer (Ashaar Farhan design) and recently made a 70 Mhz filter board. (4 coils 5 caps) I swept the filter and found that it rolled off at 15 Mhz instead of 70. I checked the design with Elsie and LT spice and they show 70 MhZ rolloff with no pad. Presently I'm rebuilding the board using your "Dot" method. If I'm coming out of the si570 oscillator chip through a 50 ohm cable, do I need a pad? Should I use a "T" pad using 3 resistors for 6 dB down on the board. I can't seem to find info about this.. Thanks for your thoughts KM4TRT

What about the variable cap? Doesn't adjusting it get a better waveform?

Ok, now you're shaming me to walk over to the parts bin and pull out a color burst xtal and join the CBLA! How much attenuation did you put inline with the MMM enroute to the analyzer's front end? I can see the inline one at the SA's BNC input. Gotta go back to your video on how not to blow up your SA! I'm always paranoid about overloading and damaging the box and usually use a attenuator coupler or a sniffer loop. 73 - Dino KL0S

Where can I learn radio fundamental from scratch?

Any idea as to how much per is coming out? This is a QRPp rig. One of the little guys! Have you made any QSOs with something like this? This is a good demonstration of test gear. Almost have me convinced I NEED a 'scope! 73 Jeff K7AIL

That's nice, but by how much it attenuates the fundamental? It's a passive filter, as far as I know there will be some attenuation

Are those ceramic capacitors on the filter?

One wonder if its possible to get a (SECOND HAND) half way decent "Digital radio" on one of those swap meet reunions... I'm a new Ham "Just get my licensing... and was wondering.. also perhaps other question is that I have a BaoFeng radio out of ebay,, I have perhaps the cheapest possibly spectrum analyzer, see many people using frequencies and I just can not hear or interact with them.. how do one get the radio to work?? Thanks in advance.... hope to hear from you soon.

i would like to know how to build an high power "exceeding past" legal limit low pass filter. or at least see one and it's construction. and if at all, see one made with air variable caps. if that would change the filtering frequencies. chopping harmonics off closer to the base frequency. raising the clamping frequency.

Please would explain the function of the variable capacitor in the tank circuit.

so then, technically (if you have appropriate HAM license to do so), you could run this out to a 50ohm coax, and then into a 50ohm antenna array and it would be broadcast? Wouldn't you need to maybe increase the power some before hitting an antenna?

do they have any free software available for apple products or only windows