My hobby goal is to understand the basics of RF design and construction, not plug together modules like I was playing with blocks. This is the channel where I can learn RF electronics. I like the way you try to build with whatever you have in the junk box to see how to make less than optimal parts and circuits work together. That provides us with insight into how electronics works in a way that simply buying optimal parts and sticking them into optimal circuits simply doesn't.

@acestudioscouk-Ace-G0ACE

4 ай бұрын

Totally agree!

First Contact on DSB this morning. 10M wide open. Worked Alex UA3QKA on the DSB Transmitter lash up on bench. That's over 7100 km. I think I have a transmitter!

Bill Meara has 'the knack'.

For years I've messed with BD139 and IRF510's, then at a Hamfest I found a lucky bag containing ten genuine 2sc1969. Real rf transistors, what bliss, besides the fact that they work as the data sheet states, they don't blow at the slightest impedance mismatch. 73 Steve M0KOV

@MIKROWAVE1

4 ай бұрын

Those old CB transistors are proper and rugged!

@Chris_Grossman

4 ай бұрын

According to the Mitsubishi spec sheet they have built in emitter ballast resistors, most likely one on each emitter stripe, to guard against thermal runaway and emitter current hogging.

@MIKROWAVE1

4 ай бұрын

@@AlexejSvirid I just bought a tube. Let's see.

@Dazzwidd

4 ай бұрын

they are good, so are the 2SC1306 and 2SC1307. Those ones will work well beyond 50mhz.

@Dazzwidd

4 ай бұрын

@@MIKROWAVE1 I bet they're faked

Soldering the bias reference diode to the output transistor heat sink is a good idea. I will probably use that in a future project. Thank you.

Genius move, nothing worse than trying to use the same mixer/modulator on Rx&tx, chasing instabilities is a pain at 3.5/7mhz never mind 28mz, they are much better balanced when separate, plus well screened(I have an obsessive screening problem!!!) Great job, brilliant video anyone who is doing everything they can to encourage homebrew deserves a medal!! don't you just love the smell of solder!!!-73s all -scott M0KJZ

I picked up on the narrow and wide aspect of the amplifier. New to me and makes a lot of sense, as does building rather than plugging modules together. It would be interesting to consider a cost comparison when the project is completed. Thanks and best 73.

I think you should put the tuning control on the side of your dominant hand. You don't want to reach across the display (if you have one) to tune. Great project, and advice for organizing a new project.

@MIKROWAVE1

4 ай бұрын

Excellent advice!

👍 Excellent as always Mike, thank you. Golden nuggets of information.

@Dazzwidd

4 ай бұрын

These series of video documents of his home research and development experiments are extremely educational. Better than books I believe, especially for the unfamiliar person with an interest but who is forming a foundation of rudimentary principles.

Great Information !

Great Information !!

My Wee Willy DSB on 75M uses a separate receive and transmit board with shared vfo and works quite well plus easier to make changes to one or the other ;-) 73, wa4jat

@MIKROWAVE1

4 ай бұрын

It is so easy for these projects to (as they say in OZ) - turn into a WOG. When Ugly really gets ugly! Reach into your junkbox and squeeze and pull out a ball of stuff. Best to hide this in an opaque box!

@marknesselhaus4376

4 ай бұрын

@@MIKROWAVE1 I would not go so far as describing it as a WOG but it does show the simplicity of it all and still work well. I am closely watching your progress on this 10M rig. The Wee Willy might be fine for 75M and 40M as I have made many solid contacts in the past with it but as for 10M, it would need a redesign of the PA and the receiver front end in your direction ;-) Long live junk boxes 🙂

👍Thank you sir.

@MIKROWAVE1

4 ай бұрын

Thank you for watching.

Getting behind on your videos again. But another good video.

@MIKROWAVE1

3 ай бұрын

Binge Binge!

Using a Children Band (CB) radio transmitter stages as a model for 10 meters! Well why reinvent the wheel when some else has done it right.

You're taking a lot of ideas from Citizens band and that makes sense because RF engineers had to work on them for a living and the manufacturers wanted to keep the parts count down

Mike, at 25:35 you mention something that sounds like 'squegging'. I've never heard the word before. I have about 60 years of electronics under my belt, but little RF design, (which is why I'm here, because it's fun.) Can you explain that term for us? Same with 'TPTG'. Does that mean 'tuned plate, tuned grid'? Thanks.

@MIKROWAVE1

4 ай бұрын

Squegging is an archaic word that describes a high frequency oscillation that is building and falling at an audio or ultrasonic rate. Sometimes it is called superregeneration or even motorboating today. Yes TPTG or in this case TCTB Tuned Collector Tuned Base feedback oscillator.

Very interesting but a little beyond my ken, ie: impedance matching sections and broadband vs. narrowband characteristics. But I like your simple as possible (but no simpler!) and economical as practical design philosophy. Obviously, you came from the private sector.

@MIKROWAVE1

4 ай бұрын

I tried to keep my work life separated from my radio hobby by 30 years! By the way, I worked for many sectors for countem-17 companies, before retiring last June. Yay! By the way I thought that the modules I designed for military aircraft were the pinnacle of quality requirement devices, till I worked in the automotive sector and found out they wanted more reliability - and at zero cost.

Very good video as always. You always refer to parts recycling and procurement from cheap sources which I agree. But when comes to high frequency cores it sounds like there is no alternate solution except to go to classy supliers with their ridiculous prices. There should be a simple but more systematic way to check core material than put it in the circuit and see if it heats up?

@MIKROWAVE1

4 ай бұрын

By using the published data from the manufacturers Iike Amidon, Micrometers and Fair rite etc...and doing some Gauss equations, you can estimate this stuff. But transformers with cores of any type have never been as simple to predict as other components. I made a dandy 28 MHz transformer out of a random choke core out of an old ATX computer supply and every toroidal used as a resonant in this design can be done with a few turns of wire on a Bic Pen just like they fid in the CBs ; they never used toroids. cost essentially zero dollars. Toroidsl are cheap, so that is why we like them in ham projects.

@Chris_Grossman

4 ай бұрын

@@MIKROWAVE1Toroids also have low magnetic leakage and coupling!

@MIKROWAVE1

4 ай бұрын

Yes true! And this can help with isolation and unwanted feedback. But shielded can slug tuned inductors can turn out to be cheaper in production than toroids and trimmers for many applications.

I thought you might have been going to pinch the solid state TR switching from the CB radio too for a new line of education 😅

@MIKROWAVE1

4 ай бұрын

Excellent! Yes they have used the passive and active diode switching idea, forever. Its only the really old sets that actually used a relay.

@Dazzwidd

4 ай бұрын

@@MIKROWAVE1 They indeed have. It works well and is seen in vhf and uhf commercial rigs commonly too, although there the diodes are more specialised than they are at HF... I believe they are PIN diodes in the PA output interface at those frequencies. At HF and low powers the diodes can be much more garden variety. Anyway, this technique is not as commonly understood and mostly people just use relays because conceptually it's much simpler, although the use of diodes is actually fairly simple

@Dazzwidd

4 ай бұрын

I should say it's simple to use purely for TR switching. I remember you saying about complexities perhaps creeping in if you use diode based solid state switching everywhere... well yes, there's more circuit blocks being controlled, but if you deal with the TR switching first, you might get a sniff of where to go to simply implement it elsewhere. The beauty of home experimental R&D is it can lead you down divers paths of expanding enlightenment and understanding which then positively "infect" future projects 😅

😂😂😂😂

What is the bandwidth in terms of percent? 2% is about 500kc or the novice band. TOKO transformers made retuning easier than iron donuts, but those are like 2SC1973/1969 on eDumpster - high in price and faked. The last two series have been interesting. The 1920s night would be cool but slot deaf in one ear and mostly deef in the other makes cw hard to copy. Had a navy guy work with me on lunch years ago at a job to get my speed up to pass the cw test. We had conversations wordlessly. CW. Dad joke and I am rambling like its 160. 😂

@MIKROWAVE1

4 ай бұрын

My Elmer was 75m SSB Emergency Net man and he struggled to even give us the 5wpm Novice Test! My buddy and I were fascinated by CW. I rigged up ARC5 transmitters for both of us and we never looked back.

73's🎙KD9OAM🎧