This is brilliant, thanks for the great explanation of what the components are doing. I will be on mouser tonight ordering parts. Thank you for taking the time to do this. Regards Chris
Ah, the joy of oscillation! Yet I am troubled by the anxiety of Unwanted Harmonics. Not specifically from what I see here, it's just a sort of scar tissue I have from past experience. What kind of energy does this build put out up around 14, 21, 28 MHz?
One sddition to the files at Hackaday: It would be great if the documents could also be uploaded as an PDF. The are more secure (virus etc.) and can be read by us Linux guys with less effort. :)
Please clarify; Q1 (2n3904) is being used as an emitter follower which I understand to have a voltage gain of less than one. This seems to violate the Barkhausen criteria so I don’t understand how this circuit oscillates. Help!
The combination of the negative feedback from emitter to base and the capacitive voltage divider provides sufficient gain to satisfy the Barkhausen criteria. This is a common Colpitts circuit. Farhan's use of the capacitive divider as both the capcitive part of the tank circuit and as the feedback circuit for the oscillator is less common but also well documented and not that unusual.
It's brass. This will decrease the inductance, as apposed to ferrite increasing the inductance. So it will tune from the lower side of the band, to the higher, as it's screwed in. I did read where someone said they used an iron bolt. This I believe will work the other way. Like ferrite. I imagine you would then need to take that into account with the coil. Turns and spacing. You would then be going from the higher end of the band to lower.
Is any one producing the coil former on Etsy? I can't justify buying a 3D printer to the XYL. We live out too far in the sticks to have any maker shops. I might be able to cobble a former using 1/2" CPVC pipe, end caps, a block of wood and epoxy.
Ralph, I experimented with the bottom half of a ball point pen (Pilot brand) as the coil former and it works. I have a printed former now, but could have made the pen work. You should be able to make up some 1/8 ply formers for the ends and to support the 1.4 20 nuts and glue it all together. Also there is the glue stick method discussed various places.
Really fantastic work Dean. This is a great contribution to home brew.
Excellent! 73 de ai4ot
This is brilliant, thanks for the great explanation of what the components are doing. I will be on mouser tonight ordering parts. Thank you for taking the time to do this. Regards Chris
This is awesome! Thanks for this video and successive ones. I’m excited to follow along and build my own!
Very good video Dean. So well explained. Thanks.
Going to jump in and do this! Been away from the solder for too long. 73 de W2DAB
Hooray! Welcome to the project Dave! 73 Bill
Thanks Dean, great video, I’m going to give this a try
Very instructive!!!
Ah, the joy of oscillation! Yet I am troubled by the anxiety of Unwanted Harmonics. Not specifically from what I see here, it's just a sort of scar tissue I have from past experience. What kind of energy does this build put out up around 14, 21, 28 MHz?
Perfect, thank you.
I will order some parts and follow ther series. vy 73
One sddition to the files at Hackaday:
It would be great if the documents could also be uploaded as an PDF.
The are more secure (virus etc.) and can be read by us Linux guys with less effort. :)
Awesome!
Please clarify; Q1 (2n3904) is being used as an emitter follower which I understand to have a voltage gain of less than one. This seems to violate the Barkhausen criteria so I don’t understand how this circuit oscillates. Help!
The combination of the negative feedback from emitter to base and the capacitive voltage divider provides sufficient gain to satisfy the Barkhausen criteria. This is a common Colpitts circuit. Farhan's use of the capacitive divider as both the capcitive part of the tank circuit and as the feedback circuit for the oscillator is less common but also well documented and not that unusual.
what material is the screw /bolt?
It's brass. This will decrease the inductance, as apposed to ferrite increasing the inductance. So it will tune from the lower side of the band, to the higher, as it's screwed in. I did read where someone said they used an iron bolt. This I believe will work the other way. Like ferrite. I imagine you would then need to take that into account with the coil. Turns and spacing. You would then be going from the higher end of the band to lower.
Is any one producing the coil former on Etsy? I can't justify buying a 3D printer to the XYL. We live out too far in the sticks to have any maker shops. I might be able to cobble a former using 1/2" CPVC pipe, end caps, a block of wood and epoxy.
Ralph, I experimented with the bottom half of a ball point pen (Pilot brand) as the coil former and it works. I have a printed former now, but could have made the pen work. You should be able to make up some 1/8 ply formers for the ends and to support the 1.4 20 nuts and glue it all together. Also there is the glue stick method discussed various places.
Ralph: KQ4AOP and N9TD have both offered to print and send coil forms to those (like me!) who don't have 3D printers.
@@nohill4climber Thanks for the reply. Pens and plywood I have.
@@soldersmoke Thanks I'll be in touch if my DIY option fails.
Excellant instructions, clear concise and very understandable. Dana VE6KBI