Ham Radio - Build your own QRPp CW transmitter 

Linus:" I can build PC's" This dude:" hold my altoids tin"

One of the ideas that went well at a local club that I suggested was called Desert Island Radio. Small groups were given a small pile of components and a few hand tools and the challenge was to build an 80metre transmitter. Some suggestions were put on a chalkboard, and the idea was the first team that could be heard on a receiver at the front of the hall. Included was a common QRP crystal. I think the record was somewhere between 10&15 minutes. A couple of times we ran this competition some even managed a transceiver.

Great video! I would like to suggest that mounting a plug for the crystal instead of the crystal itself to the board will allow you to change crystals and work different frequencies. That's how we did it back in the day. ;)

Yep back in the day we would saddle are dinosaurs and go foraging for vacuum tubes to build transmitters ; )

Hello Kevin, What is actually generating the TONE? Is the tone being generated from the circuit? Is that what the first 2n2222a doing then generating it to RF on FEQuency via the second 2n2222a and crystal? Thanks a bunch in advance. I know Kevin has a lot of videos so if anyone else can answer this for me that would be GREAT!

Just a tech, but I understand 80 percent of this, have a great time studying and learning the rest. My wife watched a bit, thinks you're a NASA tech building something for a moon rocket. She still doesn't believe that some of us actually do work on and work satellites.

Nice job. Thanks for making the video and I especially like that you actually made a contact with it. Keep up the good work, and CU ON CW!

Heh! Good job, Kevin. Surprised to see a wooden key. I'm doing one of those myself for laughs. I'm in the middle of a 807 tube tx for 40 with a 6AG7 oscillator. No smoke yet, so wish me luck. Thanks for the vid. We need more stuff like this for kids and frustrated new hams....

To: KB9RLW / Kevin Loughin, You can know that one of the rarest bits of information about Ham Radio that I One of the things I struggled to find, is just something simple and basic for a beginner and Technician. That is for someone to tell me a good band and frequency to use for transmitting and receiving with slow CW. Well, you just gave it to me. Although people working to teach others are helpful in their own way, sometimes they offer more than a few general suggestions all at once, rather than just TELLING the new ham something specific. Usually, when beginners ask, they get all kinds of evasive answers or odd answers, or just too many answers all at once, as a kind of rhetorical response. As a beginner, all I really wanted was for someone to suggest to me, a project, or a frequency / band to operate on as a primary focus to initiate my learning. Here is what I just got from you. CRYSTALS for the CW bands on 40 meters... good for SLOW CW are crystals in the 7.05 to 7.055 range or 7.1 to 7.122 Mhz...etc. You one smart fella. Whether intentional or not, you seem to adopt the KISS PRINCIPLE into your messages. (You know....Keep It Simple Stupid....) Bless your little pea-pickin' heart. I really like what you do! KNFNNT

From Detroit, I made a 600+ mile QSO on 40m, with 200mw output. I got a RST 339, but it was quite cool making a contact with two 2N3904s and about ten other components, including the filter. Anyone trying QRPp or QRPe should know that SWR and coax loss are major factors. I used good quality RG6 and a dipole tuned for the CW end of 40m. I made contacts to Connecticut and Wisconsin, too. The Kansas QSO was about 2 hrs after sunset and the other two were midday.

Thank you for this video. I think its a very worthty explanation video. I examples how in history radio's were build. For my lectures as a teacher in physiisI do have a few questions: 1) does the frequenty of the crystal set the transmissionfrequenty? 2) if I would replace the amplifing transistor with a transistor with a highr power, would the power of this transmitter be bigger? 3) In the stores I can bey electral components like resistors, condensators and Inductors; are those premade Inductors also usable, or do I have to make the inductors myself? Again, thank you for making this video.

Kevin I find that hot gluing an old gift card fits just right in the bottom of the tin. For the holes I use a 1/8th drill bit then a reamer. Great channel, I always watch your videos. 73 wd4dda

Great video Kevin, it makes me want to brush up on my CW and give it a try, (again!).

perfect starter project. Thanks! Earned another sub :)

Nice build video Kevin. I picked up more information about circuitry during explanation of the schematic. Certain people in a persons make an impression on one''s learning process. That circuit has been explained to me many times before and it didn't click in my brain why. Your explanation helped. Still learning at 70.

Re drilling thin metal, use a step drill .Works a treat. Excellent video.

There is a few things I noted. The output amplifier is very heavily coupled to the oscillator. I would reduce its value to 220pf and see if the output changes much. If it doesn't, then its better as you have reduced loading on the oscillator. Also the output PA circuit would be better matched to the output LPF by using a coupling transformer. A small 4:1 transformer wound on your toroid would improve things. The collector of that PA would have a very high impedance compared to the 50 ohm load. In fact if your PA was only producing 500mW (and it's not) you'd be looking at a collector impedance of around 140 ohms impedance if your power supply is 12V. At 200mW it would be 360 ohms. If you were getting 350mW, it would be 200 ohms and a 4:1 balun would give you the best power transfer.

Yes Colpitts oscillator....I always remember because it starts with a C! For tapped capacitor.

you must know / tell which toroid you used! otherwise it is no use, we can't do anything with it. Was it not a T50-2? friendly greetings from The Netherlands! Rob.

Kevin, really nice and educational video. It revisits the idea of how we used to make xmtrs and rcvrs many years ago. Thanks for reminding us it still possible to do cheaply and effectively even in days of smd electronics.

Altoids tin for a pixie tranciver, Altoids tin for Antenna. Altoids tin for fire starter, Altoids for beef jerky/peppermint. one more for instant tea/ coffee, and log book. It makes for a swell week end. tks for show and tell 73 de kv4li

Ahhhhh, Hello Kevin, today I sit once again rewatching this awesome video. However, I must add,,,, I popped into the Living room and switched on the wide screen Tv and sent this video to our Apple TV box. Coffee stationed to my right and toast stationed to my left. This is my preferred method now to enjoy watching your videos. I really like the schematic here. Very clear, certainly large enough to see the components and well lit. Way to go on the teaching as well. 73's Kf2ms

Hey Kevin.. This was just recommended for me to watch on YT home page! They've not forgotten you!

Question/Challenge: Can You Combine All Of The Other Elements Of The Radio Setup Into The Altoids Tin? Not The Telegraph Key, But Everything Else. Bonus Points If You Can Make It Portable!

Put some wood stain on that nice key kg6mn

How far of a distance can you talk from with the ham radio?, can it be like in stranger things where it travels from Hawkins Indiana to Salt Lake City Utah

Nice job on the mini 2 stage transmitter. Nice timely QSO. Can't beat that. And, apparently only one Altoids tin to complete the job !! Now you just need a crystal socket on the board and you are set. You could even use it, if you had a frequency counter, to check crystals for operation and frequency (at least crystals in the 40 meter band). lol 5 *

Hi Kevin! I Have one problem. What is Your power? On Your scope is sinus 4volts p-p. By standard formula 4V p-p on 50 ohm load is 80 mW PEP, or 40 mW effective power. Where I make mistake. 73! Ed

This is very informative thanks a bunch. If I wanted to make one for 10 meter band, apart from the crystal, do the values of capacitors in the first stage oscillator change and if so would it be to resonate at around 28MHZ?

very impressive, OM.... tnx for the demo.... ur gud fist...... 73s..... from Bill, KE1LC

When Kevin showed the harmonic reduction due to the LPF, did I miss the value of the load resistor terminating the filter output? This value can make a BIG difference to filter performance, and therefore the harmonic level too! Also, if it's R ohm it's easy use a scope to calculate the RF power out from (Vrms^2)/R.

Nice video. Nice transmitter, and of course, it works. Trying to figure some stuff out to operate where my employer is housing me. Something like that might just do the job. Tnx for posting. 73, KK7XE

L1, is it 6,7, or 10 turns? You said 6 or 7. Your schematic shows 10 turns. I'm gathering my parts to make a go at it. Thanks. de ke4rk

“T-hotally spaced out Doode!” 👍👍

I would love for the FCC to bring back CW novice without voice with 3 to 4 license tiers. Yes, a kind of key club for keyers. Today's hams are only 11 meter refuges.

I have an original Rockmite to finish, just need to install the “upgraded final” and mount it in a pin Altoids tin that has been earmarked for this since 2003 (or maybe 2005). Great project, great video, thanks for posting. 73s N1XF

Seems to me, the QRP Frequency on 40 was 7.040, then outta nowhere, some digital Lid, decided thats where they should bring there garbage ! " FNG 's " !

I have a question: If AM frequencies are lower (lower hertz) than shortwave frequencies, then why don't AM transmissions travel farther?

Very nice! I just cloned your circuit and it is very slick... tks! 73 de K7ZB K Those are T50-2 toroid cores...

Awesome

I just built a QRP Pixie. Wondering how much wire to coil around a broomstick for a decent antenna.

This won't work to reach iss right?

it's a class A amp, so efficiency will be less than 30 percent, but bc it's two stages, it will be even less like or less 0.01, so 10mW at max

at one minute you said plethora the same way I do. ple Thor ah. also the transmitter looks amazingly like a pixie two. great job in making the enclosure and all that other stuff. it's the last steps that make it into a complete project. great job!

This was great! Have you ever built or have a video about a transmitter that utilized tubes? In very interested in building my own classic transmitter.

I'm having a heck of a time even with RBN "hearing me at 8/10th of a watt through a compromise antenna

to me THIS is ham radio. diy minimalistic rig , then see how far it goes and how to optimize or add to it. thanks for the demo! 73!

Gonna do this Manhattan style

Thanks very much for showing how you use the breadboard to put together this circuit. I have numerous altoid projects and enjoy my pixie. N9egt

Picofarad : Peek- O - Farad, aka, " Puff " ! 👍🙄 Just Say'n !

You lost me at 0:00:01. I was lured by the Altoids Tin. Now my brain hurts lol

Could you explain how you hooked up your receiver to the transmitter? Very interested in that

I built this. It does well for one watt from 2 transistors. N9egt

Great video Kevin! For those unable to send in morse code, wondering what would be needed to connect this up to a Raspberry Pi and run morse code software

What an outstanding video! Very nicely done, I really enjoyed this. I'm a noob to circuitry so it was still a little quick for me at my level, but still very very good. Thank you.

Very cool.

I like to see someone build a trench radio transmitter and receiver

Tapped vaps, volpits. Tspped coil, Hartlry. Nice vid. 73 WA2KBX

My local bargain shop sells biscuits in nice tins for $5. Biscuits a bonus, tins great for these projects Thanks for presenting, 73's, Barry, VK2FP/AG7VC🙂

What does "DE" mean? I see that a lot and just thought my software was picking up noise like when it just says T T T T.

Excellent job Kevin. I have a question or two. How did you insulate the underside of the circuit board from the Altoids tin? Also, it looks like the filter inductor was a T-50-3 type of toroid. What type of toroid was used for the RF choke L-1?I love making small circuits and stuffing them in Altoid tins. Thank you for making this very interesting video.73 de K7RMJ Frank

I wonder if this could be used for QRPp in the phone section of the bands. Making a low power TX radio for next to nothing on one part of the band with a variable VFO over a few Khz. With something that size it would be good for backpackers and SOTA.

I enjoyed this video. I would like to build this for 20 meters cw. What would your recommendations be concerning the torid band pass filters? What other recomendations would you have ? Ron K5QJP

Would it work for CB if i changed the crystal and the low pass filter? (ofcourse with modulation)

A QRP tx is so easy to make and they work. And with a simple rx, wire aerial and tuner you have a complete portable QRP station and the battery will last a long time. G4GHB

Can you build a tiny receiver to go with it? I know small ham receivers are a little bit fiddley but could you do it?

Am needing a transceiver mainly.

1.5 w on the one that I built.

thank you I need circuit diagram for transmitter video signal for 1 KM . BEST REGARDS

Very clean CW, sir.

Hi it is great to see hams doing design & construction projects. It seems like there only cb rs are the only ones joining the ranks any more, those that have no electronics knowledge nor do they want any. Again, great video!

What a great tutorial!!!!72 DE K0JQZ

FB project and greetings from Bloomington, IN De ki4uta

What are the core materials?

I wonder if this wouldn’t work with the inductor coils just wound around a stamp of McDonald’s plastic straw and paraffined, no ferrite? Thanks for nice vid!

That was cool! Thank You 😊

Mr Kevin sir, it's a good practice to use two reverse and forward connected diode pair to avoid transistor saturation and over voltage burning in case extra voltage dropped in.

Mr Kevin, sir, have you ever built a kit like KnightKit T60 and companion receiver R55?

Hi fellows ! Did anyone know from where to buy one already operational ? Please let me know and give me the price . Thank you and keep in toutch !

Any chance this design can be upgraded to include a VXO? Can you swap in a VXO for the xtal without having to swap out any other parts?

How bout some more simple radio projects, more transmitters, TRX and regens

Excellent!

So we can get communication when everything goes down. In case of a global blackout.

Excellent

Dug through your channel but couldn't find any videos on building a similar QRP CW receiver. Any tips or resources you can direct me to for that? What kind of antenna are you using. New to this but very interested in low power CW communication on simple homebrew equipment. This is a great transmitter though; exactly what I'm looking for!

Personally I've found perf board causes strange induction issues

Can some one please give the type of ferrite cores used.

Nice job ........... great explanations ....... love those radio hams ............

Kevin, where are you getting the toroids?

Did anyone else have a little nerdgasm when the contact was made? This vid was so much fun - tnx :)

Wouldn't it be a Pierce Oscillator since it uses a crystal? I always memorized it by the first letter: Pierce - Piezoelectric Colpitts - Capacitor Hartley - Henry/Inductor

excelent job ..!

What is the core types and the actual uH value of the toroids please? Nice build!

Nice rig, gud DX OM 73 de KT1R (still loads of snow up here in Maine, ugh!) (as of March 27)

Hi Kevin, I understand how the circuit functions as a transmitter, but the one thing i dont get is how you hooked it up for recieving. From what i can tell, the switch just swaps the antenna between the transmitter being on it and the reciever hooked to the rca jack?

Great video. I need to find a kit or parts and built my first tranceiver. What model scope are you using in the video? Russ - AD0QH.

Good vidéo Tx QRP 72's Fab F5RLW

i am new to electronics and ham radio but which component would you use to change the bandwidth of a receiver? i thought i would ask you because you seem to know what you are doing

Great video! de N3PEE

Hi Kevin - Great video. I'm ordering parts to build the QRP TX. I enjoy your loop antenna videos too. In my HOA situation, I may need to build some. Are both toroids 17mm? I found some on Amazon that are that size. Does the mix matter or at these frequencies, is virtually any common mix likely to be OK? Looking forward to building this rig. 73, John, KJ7RDV