Thanks for the video. I followed your design with a few exceptions. I used 2 paper towel cores. I split one core and then cut off about 10mm / 3/8" along the same split cut so that core could be squeezed together smaller to slide inside the outer core. Your bigger diameter thin wall PVC might have given me greater pF as my end result. I slid my smaller core inside the outer core and taped it so it wouldn't expand Then I took out the inner core and wrapped it all the way around and the full length of the core with one piece of foil and then taped the foil. Then I wrapped the outer core with foil all the way around and full length and taped it. I taped my wires to the foil much the same as you did. My end result was 200pF. There's two things I'll do different if I make another one. That is to wrap more foil around the inner core so it will fit a little tighter and increase the capacitance because of closer proximity of the two sheets of foil. The other thing is leave 50mm to 80mm / 2 inches to 3 inches space at the end I'll hold to push / pull. That's because hand capacitance aggravates the tuning. I've watched a lot of your videos. Thank you.
This reminds me about Mr Villard's loop. The advantage of that was that the capacitor is integral part of the loop antenna and did not need wire connectors, since it was inductively coupled with the receiver. I wonder if anyone tried transmitting with Mr. Villard's antijamming loop.
I used a cardboard paper towel tube with one 6" square of foil, and a sheet of copy paper with one 6" square of foil around it with enough paper exposed at one end of the cylinder to hold it for sliding across cardboard tube. With just the paper as the dielectric I usually get over 1200 pf. The printer/copier paper worked for 7 watts CW on a mag loop. Next time I will try a tube with a smaller "trimmer" cylinder for fine tuning. I found that rotating while sliding makes for smoother tuning of smaller increments, preventing the friction skips and jumps.
Is this the same idea used in so many homemade 11 meter cb amp videos I see being used as a tuning capacitor for input or output tuning???? See them in BBI Amps videos all the time. This looks like those copperish looking ones he uses. What amount of rf power can these hold up to if used on rf amp output side??
Now that's granular control of a small value of C. Wonder what the breakdown voltage might be? If really high, would this not make a super easy to adjust mag loop cap? God I'd love to visit your magical land someday. Thank you for the wonderfully interesting and really creative ham videos! 73 OM
What's an experimenter without teeth to cut with or toes to clamp his work in place! Aside from the total "plate" surface area, the two most important variables for a capacitor are the spacing between the plates--in this case the thickness of the outer tube (plus whatever clearance there is between the inner and outer tubes)--and the dielectric constant ( _k_ ) of the material(s) separating the plates--here, PVC and a little air. The closer the plates the higher the capacitance. The greater the dielectric constant the higher the capacitance. Air has a _k_ of slightly more than 1.0. PVC is about 4 (and other common plastics close to that). Glass can be as high as 18. Ethylene glycol (antifreeze) is 37. Distilled water has a _k_ > 80!
@@vk3ye That's a shame. Many talked about tuning capacitor. But I saw a potential for your variable capacitor as modified electrophorus. Example th-cam.com/video/axgG_aSLKPM/w-d-xo.html. So, say you charge the two outside plates to a high voltage, one + the other - with a center fed Cockcroft-Walton voltage multiplier. Then if your moving plate were connected to ground through a load, you could turn mechanical energy into electricity alternatly pushing electrons from your moving plate ground, and later pulling electrons from ground to your moving plate, throug a load to do work. Since the capacitance and consequently the charge is rather small, that means frequency is rather important for reasonable power generation. A rotory variable capacitor might less vulnerable to vibrations at higher frequency. I hope this comment inspires high voltage power generation experiments.😁
I saw an article sometime in the last couple of years, possibly in the WIA's _Amateur Radio_ magazine, which described a loop featuring a trombone tuning unit fabricated from concentric copper tubes and teflon spacers.
You can use tubing and slip clear plastic flexible tube over the top. If you get the right diameters the tube will be a tight fit into the middle and it will fit nicely into the outer tube. If you use copper you can solder it too
Thanks for the video. I followed your design with a few exceptions.
I used 2 paper towel cores. I split one core and then cut off about 10mm / 3/8" along the same split cut so that core could be squeezed together smaller to slide inside the outer core. Your bigger diameter thin wall PVC might have given me greater pF as my end result.
I slid my smaller core inside the outer core and taped it so it wouldn't expand Then I took out the inner core and wrapped it all the way around and the full length of the core with one piece of foil and then taped the foil.
Then I wrapped the outer core with foil all the way around and full length and taped it. I taped my wires to the foil much the same as you did. My end result was 200pF.
There's two things I'll do different if I make another one. That is to wrap more foil around the inner core so it will fit a little tighter and increase the capacitance because of closer proximity of the two sheets of foil.
The other thing is leave 50mm to 80mm / 2 inches to 3 inches space at the end I'll hold to push / pull. That's because hand capacitance aggravates the tuning.
I've watched a lot of your videos. Thank you.
I've actually done something similar when I was a kid but I used a paper towel tube and a sheet of copy paper as a dielectric instead of pipes.
This reminds me about Mr Villard's loop. The advantage of that was that the capacitor is integral part of the loop antenna and did not need wire connectors, since it was inductively coupled with the receiver. I wonder if anyone tried transmitting with Mr. Villard's antijamming loop.
Can someone help me to know why my magnetic loop is increasing the static of the MW frequencies rather than reducing?
I used a cardboard paper towel tube with one 6" square of foil, and a sheet of copy paper with one 6" square of foil around it with enough paper exposed at one end of the cylinder to hold it for sliding across cardboard tube. With just the paper as the dielectric I usually get over 1200 pf. The printer/copier paper worked for 7 watts CW on a mag loop. Next time I will try a tube with a smaller "trimmer" cylinder for fine tuning. I found that rotating while sliding makes for smoother tuning of smaller increments, preventing the friction skips and jumps.
What was its diameter, and was that 120pf or 1200pf?
Is this the same idea used in so many homemade 11 meter cb amp videos I see being used as a tuning capacitor for input or output tuning????
See them in BBI Amps videos all the time. This looks like those copperish looking ones he uses. What amount of rf power can these hold up to if used on rf amp output side??
Chilled video Peter! DIY neighbours and those birdies! Your knees must hurt tho! Thanks
This vid could have done with some tight editing.
Now that's granular control of a small value of C. Wonder what the breakdown voltage might be? If really high, would this not make a super easy to adjust mag loop cap? God I'd love to visit your magical land someday. Thank you for the wonderfully interesting and really creative ham videos! 73 OM
Can we use this capasitor in radio tunig
No reason why not.
What's an experimenter without teeth to cut with or toes to clamp his work in place!
Aside from the total "plate" surface area, the two most important variables for a capacitor are the spacing between the plates--in this case the thickness of the outer tube (plus whatever clearance there is between the inner and outer tubes)--and the dielectric constant ( _k_ ) of the material(s) separating the plates--here, PVC and a little air. The closer the plates the higher the capacitance. The greater the dielectric constant the higher the capacitance.
Air has a _k_ of slightly more than 1.0. PVC is about 4 (and other common plastics close to that). Glass can be as high as 18. Ethylene glycol (antifreeze) is 37. Distilled water has a _k_ > 80!
Good Job, Im About To Make One Myself From Two Pvc Tubes, But Much Smaller Then You Made :)
LOL, the connecting wires for this ginormous capacitor will have too much stray inductance for HF purposes.
you know peter you could have used good Aluminum foil tape instead of that thin Aluminum kitchen foil.
Double sided tape may make a tighter flatter fix
What are you going to do with it?
Nothing! I pulled it apart!
@@vk3ye That's a shame. Many talked about tuning capacitor. But I saw a potential for your variable capacitor as modified electrophorus. Example th-cam.com/video/axgG_aSLKPM/w-d-xo.html.
So, say you charge the two outside plates to a high voltage, one + the other - with a center fed Cockcroft-Walton voltage multiplier. Then if your moving plate were connected to ground through a load, you could turn mechanical energy into electricity alternatly pushing electrons from your moving plate ground, and later pulling electrons from ground to your moving plate, throug a load to do work. Since the capacitance and consequently the charge is rather small, that means frequency is rather important for reasonable power generation. A rotory variable capacitor might less vulnerable to vibrations at higher frequency.
I hope this comment inspires high voltage power generation experiments.😁
Interesting sounds in the background. Nice video.I have all your books
Thanks David. Maybe I should stop talking more often!
Probably using aluminium or copper tubing would produce better results and make entire thing more sturdy.
I saw an article sometime in the last couple of years, possibly in the WIA's _Amateur Radio_ magazine, which described a loop featuring a trombone tuning unit fabricated from concentric copper tubes and teflon spacers.
You can use tubing and slip clear plastic flexible tube over the top.
If you get the right diameters the tube will be a tight fit into the middle and it will fit nicely into the outer tube. If you use copper you can solder it too
That one strange sounding bird!
Deve prima costruire un tavolo dove lavorare