This is a great BFO project! Thank you for using the Franklin oscillator circuit. If the crystal set 'purists' get butt-hurt about adding a battery operated BFO, that's their problem. In this hobby, we build with what we have on hand and shouldn't worry about the aesthetics of it all, especially when we are experimenting. If we finalize something then can make it 'pretty'. I truly appreciate what you do, and I always learn a lot. It's the effort and the results that count! Keep up the great work. Mike, KC0IVF
I would like someone to make a video exalting their crystal bfo without batteries as i would like to leave iit embedded in a wall or 'cave' interior to play forever and not worry about bztteries or solar power.
Thank you heaps for uploading this very helpful video. I learned about you on the Amateur Radio VK3YE channel. You and Peter are valuable sources of information and inspiration for enthusiastic folks like me with little experience. I'm about to experiment with a Franklin oscillator as I embark on a quest to make my own portable 20m CW equipment. 73 from New Zealand. ZL3ABX.
Inspirational Mike, thanks. In the Vienna (Va) Wireless Society we have at least one member who has built a Franklin oscillator and another who has been working on one. Inspired by your video, yesterday I became Franklin builder #3. It is a very interesting circuit. I got mine oscillating right away and am now testing for longer-term drift at around 18 MHz. I wonder why this circuit has for so long been ignored by American radio amateurs. There is no mention of it in Solid State Design, nor in Experimental Methods. Pat Hawker G3VA in Technical Topics of February 1990 gives a great rundown on Charles F. Franklin and his oscillator, but notes that, "Despite its many advantages, the Franklin oscillator remains virtually unknown to the bulk of American amateurs." Why has the Franklin oscillator been so ignored? 73 Bill N2CQR
A few months back I discovered the Franklin VFO circuit and am just now almost ready to build it. You covered a lot of useful information about how it can be used. There's not a ton of information out there about the circuit. Thank you.
@@MIKROWAVE1 Actually why the Franlkin circuit turned up for me was my incessant search for a "more stable" VFO. A few decades back I made a D. C. rx with a Colpitts oscillator. I never got the rx audio loud enough to suit me. So, I deleted the diode ring detector and keyed the VFO (140 mW output P to P) and made some QSOs, but I had to control my CW keying speed to keep it on frequency. lol Back then I was aware of S.M. disc caps and NP0 disc caps, but back then for me those were rare. I did find some NP0 and those were an improvement. I only recently learned about C0G caps, N150 etc. Evidently the Franlkin has some inherent attributes making it more stable than the Colpitts. Your construction tips (G1, G2) go a log way to help get the circuit working correctly. Thanks. I'm only guessing, but I suspect the reason the Franlkin wasn't more prevalent in commercial rigs is the parts count.
👍Excellent, thank you Mike. Will have to give this Franklin circuit a try. The stabilility was astounding at 21Mhz for an LC VFO on exposed breadboard.
Great Video Mike! I was flabbergasted when you put the frequency counter on the Franklin-oscillator! I have built Hartleys, Colpitts, Clapp and others and never got that kind of stability at those frequencies. Am absolutely dumbfounded at why these are not covered by the American authors--just don't get it. Anyway, I was resorting to using xtal-heterodyne oscillators to extend into the upper bands. Anyway will have to play with these sometime as they just seem too good to be true. 73...
Awesome video! I wonder if the right combination of Market Basket to Energizer batteries helps with stability? I also love that Watkins Johnson receiver you're using. Really cool! Thanks again for sharing this with us. 73's!
Very nice project and forgotten about the Franklin oscillator but gonna do some experiments with it. I'm going to use an active detector so that it has a better detection. Been fooling around with a reflex detector stage that works pretty good but it is not easy to make it regenerate so that's where this oscillator comes in handy.
Hi. I looked your video. It was a perfect study. Me also have interest in Franklin oscillator, because I never tested it before. I replicated you variant of chematic in smd components. Size 1x0.5 inch. After I begin to study spectrum by Rigol 815 spectrum analizer and sine on distortion. 9 mhz (Coil and cap.) 12 and 24 mhz cristal. I worked all day on this. What I can say about. Bipolar transistor emiter follower not so good as I thought. 2 th 3th 4th harmonics and cetr at -25-30 dbm. Without Follower 2th harmonics -25 dbm, 3th -35 dbm 4th -40 dbm. Fall away -5-10 dbm per octave. I expected better. Besides shape of sine at coil was perfect. Vary capasitors, resistors and more :) More it`s transistors. Result - 39k collector base for T1,T2, 500 ohms in collector T1, 1k for T2. Gimmick G2 tiny as possible, G1 better if 4pf. Emiter resistor in follower apr. 1k-1,5k and current T3 5-6 mA. But it does not solve the issue with harmonics. Better VFO posible as multivibrator (transistors and tubes) how strange that would be. Thanks for your chanel. Your subscriber. WBR de Vladislav R7LL 73 TU
Checkout MIKROWAVE1 Shortwave Crystal Set - BFO! Part 2 I have build this on a old school quad breadboard banana plug in end in the lab very stability play with this on the BCB 500khz to 1800khz any LC or crystal will will work.
You guys have to stop giving me ideas as I’m so new to ham lol I’m building a crystal set out of a project book might have to add this up the arse of the crystal and make a double layer enclosure.
Essas montagens para mim e fantásticas é uma pena que eu entendo quase nada mas cada momento que eu mexo no meu pequeno rádio de Galeno é uma viagem muito boa kkk. Parabéns aí você explica muito bem e para quem tá começando é muito importante eu ainda não vi vídeos seus sobre antenas mas é isso um forte 73 por k voz do deserto px1y3270🇧🇷 Rio de janeiro
I just "discovered" this oscillator, mainly as an LC test instrument along woth the lamda diode. After digging into the pre-internet info, it was no surprise that it worked. The phase shift is done by non-frequency dependent componets. Changing the voltage as a fine tune was a novel idea! As well as the gimmick caps. Always an insteresting video, what is next?
Since seeing this video and the corresponding one made by VK3YE, I've built three different variations of the Franklin oscillator guided by screenshots of the circuit diagrams shown on the videos. And I don't know if any of them work, but I suspect they may not. I thought I'd be able to test them by listening for the whistle on my factory-made receiver, yet I haven't heard a single thing as I've turned the tuners on both devices. I'm fairly new to this kind of activity, but I have built a couple of half-decent 80m receivers and transmitters in the past ..... largely using the equivalent of the 'paint by numbers' technique. So I have a question please.... how can we test an oscillator without lab equipment? Surely it would have enough power to be detected by the home station receiver just a few inches away.... or is my assumption (or method) wrong perhaps? If things always worked the first time, life might be dull and I wouldn't learn as much. I appreciate all the effort guys like you and Peter put in to sharing your knowledge. Best wishes from New Zealand.
No you are correct. It should have been heard in your receiver. Murphy's Law alone says that you will have failure until you find the one simple thing that is not hooked up correctly. Or of course the old - now I didn't consider that issue.. I was thinkin it had something to do with being in New Zealand, but it worked in OZ, so that hemi phase theory is out.
@@MIKROWAVE1 Thanks for the reply. I've since made another one or two versions of the Franklin. None appeared to work. However one day I had the breadboarded Franklin sitting next to my shack receiver after fruitlessly trying to hear a beat tone. I moved my hand near the danged thing and I heard the beat rise and fall ! I think the difficulty in hearing the tone was caused by my tuning capacitor being so big and the filter on my receiver being relatively narrow. The big variable capacitor covered a huge range of frequency, and I wasn't turning it slowly enough to hear the rise and fall of the beat on the receiver. So perhaps every version of the oscillator was working and I didn't know it. One positive thing to come out of this challenge was that I made a simple RF probe for my multimeter. It tells me whether or not there is some RF voltage present. So if I'd had immediate success I wouldn't have learned as much. Apart from the stray capacitance effect on my unshielded circuit... and some microphonics arising from bumping my breadboard construction, the Franklin seems to be very consistent and stable. I'm glad that I know about it and I appreciate your part in this. So yeah, oscillators can be made to work in the southern hemisphere. The big handicap we southern hams have is having to hang on with one hand while working with the other so we don't drop off the planet. Makes soldering difficult sometimes. I keep burning my lips.
@@MIKROWAVE1 I have work with Colpitts Oscillators (the NPN type) , Pierce Oscilators (the FET type) And with PTO Colpitts type. I am look forward to test a Frankin oscillators looks very stability at high hf bands maybe at 10 meters? I like you series on crystal radio shortwave experimenting with this an Ham radio op can be education in the radio arts.
I think the capacitors on the schematic are not labeled in a consistent way. I think sometimes we are supposed to assume pF and other times we are to assume uF. This is terrible for newbies. I t
Hi, sir. I have two questions that I'm curious about and I can't find the answers. I was able to create a diode with zinc negative resistance. It seems to work very sensitive. Is there a healthy way to permanently fix the contacts? Another question is, can I do BFO with zinc negative resistance, will that work?
I am sure that the old timers had a way with some kind of goop, spring, or containment that would "help prevent" the magic spot from oxidizing or the whisker from changing position or pressure. The Glass Germanium Diode proves that it is at least, possible. Yes on the BFO - absolutely possible with a negative resistance device, valve or semiconductor.
Hello dear OM, I am the proud owner of a BC-457-A which has not undergone any modification, vernier indicates an operating fréquence of 5,3 to 7 MHz. I Also have a BC348 receiver wich World well. M'y goal is to be able to transmit on 80 or 40 mètres bandes in CW with the BC457A. I have made a power supply that provides : + 180 volts rectified regulated. +500 volts rectified filtered +29 volts rectified filtered. Tour vidéo about this subject considérés VFO ans 1625 screen gris et thé same regulated 220 volts supply. Please, tell me, if from your point if wiev m'y voltages power supply are usables without damage for the " vénérable Command Set". I wish for moment to use or only in CW, but I don't know if the direct groundid 1625 cathodes is a suitable solution and how to do without hasard problems. Receiver please, dear OM, all congratulations for your vidéos as well as the assurance of my best 73's. F5LAS
This is a great BFO project! Thank you for using the Franklin oscillator circuit. If the crystal set 'purists' get butt-hurt about adding a battery operated BFO, that's their problem. In this hobby, we build with what we have on hand and shouldn't worry about the aesthetics of it all, especially when we are experimenting. If we finalize something then can make it 'pretty'. I truly appreciate what you do, and I always learn a lot. It's the effort and the results that count! Keep up the great work.
Mike, KC0IVF
I would like someone to make a video exalting their crystal bfo without batteries as i would like to leave iit embedded in a wall or 'cave' interior to play forever and not worry about bztteries or solar power.
A very enjoyable two part series. I learnt a lot. Thanks.
That is amazing, thank you for sharing this project.
Hi Mike. Thanks to share this project. I'll try this oscillator. 73'S!
Awesome, I really enjoyed your good videos and detailed information, thanks a lot for everything.
Thank you heaps for uploading this very helpful video. I learned about you on the Amateur Radio VK3YE channel. You and Peter are valuable sources of information and inspiration for enthusiastic folks like me with little experience. I'm about to experiment with a Franklin oscillator as I embark on a quest to make my own portable 20m CW equipment. 73 from New Zealand. ZL3ABX.
Bravo !
A trick is to glue a pair of t50-6 to increase permeability
Another great video. Had to wait until I could pay better attention to watch it. Beauty is in the devices function.
I'm always fascinated by anything to do with crystal sets.
Enjoyed the videos, for sure.
Thanks Mike for this good looking circuit. I may try it.
It works!!!!!! Franklin Oscillator is Ugly Built stability was astounding this part of AM transmitter thanks.
Inspirational Mike, thanks. In the Vienna (Va) Wireless Society we have at least one member who has built a Franklin oscillator and another who has been working on one. Inspired by your video, yesterday I became Franklin builder #3. It is a very interesting circuit. I got mine oscillating right away and am now testing for longer-term drift at around 18 MHz. I wonder why this circuit has for so long been ignored by American radio amateurs. There is no mention of it in Solid State Design, nor in Experimental Methods. Pat Hawker G3VA in Technical Topics of February 1990 gives a great rundown on Charles F. Franklin and his oscillator, but notes that, "Despite its many advantages, the Franklin oscillator remains virtually unknown to the bulk of American amateurs." Why has the Franklin oscillator been so ignored? 73 Bill N2CQR
Not anymore!
Holy Hornswagles!
A few months back I discovered the Franklin VFO circuit and am just now almost ready to build it. You covered a lot of useful information about how it can be used. There's not a ton of information out there about the circuit. Thank you.
Sometimes an experiment leads to a lost circuit!
@@MIKROWAVE1 Actually why the Franlkin circuit turned up for me was my incessant search for a "more stable" VFO. A few decades back I made a D. C. rx with a Colpitts oscillator. I never got the rx audio loud enough to suit me. So, I deleted the diode ring detector and keyed the VFO (140 mW output P to P) and made some QSOs, but I had to control my CW keying speed to keep it on frequency. lol
Back then I was aware of S.M. disc caps and NP0 disc caps, but back then for me those were rare. I did find some NP0 and those were an improvement. I only recently learned about C0G caps, N150 etc.
Evidently the Franlkin has some inherent attributes making it more stable than the Colpitts.
Your construction tips (G1, G2) go a log way to help get the circuit working correctly. Thanks.
I'm only guessing, but I suspect the reason the Franlkin wasn't more prevalent in commercial rigs is the parts count.
Very clear signal!There are no fuzzing, no electrical noise from AC/DC power supplies.
👍Excellent, thank you Mike. Will have to give this Franklin circuit a try. The stabilility was astounding at 21Mhz for an LC VFO on exposed breadboard.
A very enjoyable series,great stuff!
Great Video Mike!
I was flabbergasted when you put the frequency counter on the Franklin-oscillator!
I have built Hartleys, Colpitts, Clapp and others and never got that kind of stability at those frequencies. Am absolutely dumbfounded at why these are not covered by the American authors--just don't get it. Anyway, I was resorting to using xtal-heterodyne oscillators to extend into the upper bands.
Anyway will have to play with these sometime as they just seem too good to be true. 73...
Considering al of the feedback and sympathetic videos on the Franklin, I think it is back in play! Thanks for a nice comments.
the stability is very impressive!
fantastic
Awesome video! I wonder if the right combination of Market Basket to Energizer batteries helps with stability? I also love that Watkins Johnson receiver you're using. Really cool! Thanks again for sharing this with us. 73's!
Oh yes. It's the mixed electrochemical pile from Marketbasket mixed with Energizer. Next we bring in Safeway brand. This could be a whole new series.
Very nice project and forgotten about the Franklin oscillator but gonna do some experiments with it.
I'm going to use an active detector so that it has a better detection.
Been fooling around with a reflex detector stage that works pretty good but it is not easy to make it regenerate so that's where this oscillator comes in handy.
Hi. I looked your video. It was a perfect study. Me also have interest in Franklin oscillator, because I never tested it before. I replicated you variant of chematic in smd components. Size 1x0.5 inch. After I begin to study spectrum by Rigol 815 spectrum analizer and sine on distortion. 9 mhz (Coil and cap.) 12 and 24 mhz cristal. I worked all day on this. What I can say about. Bipolar transistor emiter follower not so good as I thought. 2 th 3th 4th harmonics and cetr at -25-30 dbm. Without Follower 2th harmonics -25 dbm, 3th -35 dbm 4th -40 dbm. Fall away -5-10 dbm per octave. I expected better. Besides shape of sine at coil was perfect. Vary capasitors, resistors and more :) More it`s transistors. Result - 39k collector base for T1,T2, 500 ohms in collector T1, 1k for T2. Gimmick G2 tiny as possible, G1 better if 4pf. Emiter resistor in follower apr. 1k-1,5k and current T3 5-6 mA. But it does not solve the issue with harmonics. Better VFO posible as multivibrator (transistors and tubes) how strange that would be. Thanks for your chanel. Your subscriber. WBR de Vladislav R7LL 73 TU
These are helpful ideas thank you Vladislav. I hope to have your level of understanding one day. 73. ZL3ABX
Hatte ich auch mit einem AM 2 Spulen Detektor und Prüfsender probiert.geht prima.
Vielen Dank, dass Sie sich meinen Kanal angesehen und einige der Projekte erstellt haben!
Checkout MIKROWAVE1 Shortwave Crystal Set - BFO! Part 2
I have build this on a old school quad breadboard banana plug in end in the lab very stability play with this on the BCB 500khz to 1800khz any LC or crystal will will work.
Thanks for promoting this idea!
You guys have to stop giving me ideas as I’m so new to ham lol I’m building a crystal set out of a project book might have to add this up the arse of the crystal and make a double layer enclosure.
Careful - this stuff is addictive.
15:32 ... your counter is in x1000 mode, correct? (OK, you said "we can't go down to the Hertz but it is sub 10 Hertz"... so yes)
Well done!
Your engineering of the Franklin Oscillator is fantastic even though it looks a bit crude.
Hi, another fantastic video series!!!
What would a tube version look like?
Thanks, Lance ZL3LAD
Essas montagens para mim e fantásticas é uma pena que eu entendo quase nada mas cada momento que eu mexo no meu pequeno rádio de Galeno é uma viagem muito boa kkk. Parabéns aí você explica muito bem e para quem tá começando é muito importante eu ainda não vi vídeos seus sobre antenas mas é isso um forte 73 por k voz do deserto px1y3270🇧🇷 Rio de janeiro
Das habe ich am Detektor mit einem Prüffsender selbst probiert😂😂😂❤
Fantastic! I wonder if it would work with a varactor diode?
No better easter youtube video!
The circuit is reproducing like a Bunny.
I just "discovered" this oscillator, mainly as an LC test instrument along woth the lamda diode. After digging into the pre-internet info, it was no surprise that it worked. The phase shift is done by non-frequency dependent componets. Changing the voltage as a fine tune was a novel idea! As well as the gimmick caps. Always an insteresting video, what is next?
Retirement actually.
Thumbs up for your retirement. Now you can radio experiment full time and share with us. Thanks!
Since seeing this video and the corresponding one made by VK3YE, I've built three different variations of the Franklin oscillator guided by screenshots of the circuit diagrams shown on the videos. And I don't know if any of them work, but I suspect they may not. I thought I'd be able to test them by listening for the whistle on my factory-made receiver, yet I haven't heard a single thing as I've turned the tuners on both devices. I'm fairly new to this kind of activity, but I have built a couple of half-decent 80m receivers and transmitters in the past ..... largely using the equivalent of the 'paint by numbers' technique.
So I have a question please.... how can we test an oscillator without lab equipment? Surely it would have enough power to be detected by the home station receiver just a few inches away.... or is my assumption (or method) wrong perhaps?
If things always worked the first time, life might be dull and I wouldn't learn as much. I appreciate all the effort guys like you and Peter put in to sharing your knowledge. Best wishes from New Zealand.
No you are correct. It should have been heard in your receiver. Murphy's Law alone says that you will have failure until you find the one simple thing that is not hooked up correctly. Or of course the old - now I didn't consider that issue.. I was thinkin it had something to do with being in New Zealand, but it worked in OZ, so that hemi phase theory is out.
@@MIKROWAVE1 Thanks for the reply. I've since made another one or two versions of the Franklin. None appeared to work. However one day I had the breadboarded Franklin sitting next to my shack receiver after fruitlessly trying to hear a beat tone. I moved my hand near the danged thing and I heard the beat rise and fall ! I think the difficulty in hearing the tone was caused by my tuning capacitor being so big and the filter on my receiver being relatively narrow. The big variable capacitor covered a huge range of frequency, and I wasn't turning it slowly enough to hear the rise and fall of the beat on the receiver. So perhaps every version of the oscillator was working and I didn't know it.
One positive thing to come out of this challenge was that I made a simple RF probe for my multimeter. It tells me whether or not there is some RF voltage present. So if I'd had immediate success I wouldn't have learned as much. Apart from the stray capacitance effect on my unshielded circuit... and some microphonics arising from bumping my breadboard construction, the Franklin seems to be very consistent and stable. I'm glad that I know about it and I appreciate your part in this.
So yeah, oscillators can be made to work in the southern hemisphere. The big handicap we southern hams have is having to hang on with one hand while working with the other so we don't drop off the planet. Makes soldering difficult sometimes. I keep burning my lips.
What about creating a BFO for 1296Mhz to facilitate a UHF Crystal set at 1296Mhz as there are radio hams up there also.
Ah yes Giiggy Hertz.
Frankin Osctllator is my next oscillator to test maybe with PTO.?
Now you're talking.
@@MIKROWAVE1 I have work with Colpitts Oscillators (the NPN type) , Pierce Oscilators (the FET type) And with PTO Colpitts type. I am look forward to test a Frankin oscillators looks very stability at high hf bands maybe at 10 meters? I like you series on crystal radio shortwave experimenting with this an Ham radio op can be education in the radio arts.
I think the capacitors on the schematic are not labeled in a consistent way.
I think sometimes we are supposed to assume pF and other times we are to assume uF.
This is terrible for newbies.
I t
Hi, sir. I have two questions that I'm curious about and I can't find the answers.
I was able to create a diode with zinc negative resistance. It seems to work very sensitive. Is there a healthy way to permanently fix the contacts?
Another question is, can I do BFO with zinc negative resistance, will that work?
I am sure that the old timers had a way with some kind of goop, spring, or containment that would "help prevent" the magic spot from oxidizing or the whisker from changing position or pressure. The Glass Germanium Diode proves that it is at least, possible. Yes on the BFO - absolutely possible with a negative resistance device, valve or semiconductor.
@@MIKROWAVE1 Thank you so much for your help, sir.
Are you using silver coated wire on your xtal set? G7VFY
Oooo great idea but no just tinned #12.
Hello dear OM, I am the proud owner of a BC-457-A which has not undergone any modification, vernier indicates an operating fréquence of 5,3 to 7 MHz.
I Also have a BC348 receiver wich World well.
M'y goal is to be able to transmit on 80 or 40 mètres bandes in CW with the BC457A.
I have made a power supply that provides :
+ 180 volts rectified regulated.
+500 volts rectified filtered
+29 volts rectified filtered.
Tour vidéo about this subject considérés VFO ans 1625 screen gris et thé same regulated 220 volts supply.
Please, tell me, if from your point if wiev m'y voltages power supply are usables without damage for the " vénérable Command Set".
I wish for moment to use or only in CW, but I don't know if the direct groundid 1625 cathodes is a suitable solution and how to do without hasard problems.
Receiver please, dear OM, all congratulations for your vidéos as well as the assurance of my best 73's.
F5LAS
Thanks for your video. I only got good result with jfet. Saludos
You could not be more wrong.
This is not ugly. This is how is should be done.
You should get rid of all that multi $100 and $1000 crap in the back.
Hee!
Great Mike,just found you on my phone really neat stuff,guess I will get the crystal set out (hi) 73 k9ut
Thanks for watching!