Cardboard Tube Secondary?
thedatastream, Fri Mar 02 2007, 12:49PMI've got a 340mm (13") tall x 188mm (7.4") diameter cardboard tube with a wall thickness of 5mm (0.2") that I would like to use as the secondary for a DRSSTC.
Are there any issues with using cardboard as the secondary? Any special treatment that I should consider?
Thanks
James
Re: Cardboard Tube Secondary?
Marko, Fri Mar 02 2007, 01:05PM
Sure, just sand off the gloss from the surface (if it has any) to make sure possibly conductive ink is removed.
I wound some of my smaller coils on cardboard due to heating issues.
It may not be as sturdy as plastic pipe but many people seem to use it and will surely offer advice.
Marko, Fri Mar 02 2007, 01:05PM
Sure, just sand off the gloss from the surface (if it has any) to make sure possibly conductive ink is removed.
I wound some of my smaller coils on cardboard due to heating issues.
It may not be as sturdy as plastic pipe but many people seem to use it and will surely offer advice.
Re: Cardboard Tube Secondary?
Dr. Drone, Fri Mar 02 2007, 04:19PM
Dr. Drone, Fri Mar 02 2007, 04:19PM
Re: Cardboard Tube Secondary?
thedatastream, Fri Mar 02 2007, 09:16PM
Fascinating, I didn't know what a sonotube was until now
These tubeas used to hold 7" surface mount component reels and have some shipping labels and KEMET printed in blue ink on the outside. I've got two of them, so I can afford to try thing out on one
Thanks for the tips so far
James
thedatastream, Fri Mar 02 2007, 09:16PM
Fascinating, I didn't know what a sonotube was until now
These tubeas used to hold 7" surface mount component reels and have some shipping labels and KEMET printed in blue ink on the outside. I've got two of them, so I can afford to try thing out on one
Thanks for the tips so far
James
Re: Cardboard Tube Secondary?
thedatastream, Sun Mar 04 2007, 10:31AM
I was chatting to Richie Burnett at the Notts Gaussfest yeasterday and he had brought a 1kW CW SSTC running on a cardboard tube secondary with 2100 turns. We observed after running it that there was quite a lot of moisture that came out of the coiform.
I was thinking about drying the secondary out in my kitchen oven (electric fan) at home at about 50C for an hour or two to drive the moisture out. I'd then varnish the coil inside and out straight away to seal it against future moisture ingress.
This coilform will be used for a 1KW+ DRSSTC design. This obviously won't run CW but the overall power levels will be similar. Will this affect it?
Comments?
James
thedatastream, Sun Mar 04 2007, 10:31AM
I was chatting to Richie Burnett at the Notts Gaussfest yeasterday and he had brought a 1kW CW SSTC running on a cardboard tube secondary with 2100 turns. We observed after running it that there was quite a lot of moisture that came out of the coiform.
I was thinking about drying the secondary out in my kitchen oven (electric fan) at home at about 50C for an hour or two to drive the moisture out. I'd then varnish the coil inside and out straight away to seal it against future moisture ingress.
This coilform will be used for a 1KW+ DRSSTC design. This obviously won't run CW but the overall power levels will be similar. Will this affect it?
Comments?
James
Re: Cardboard Tube Secondary?
Steve Ward, Sun Mar 04 2007, 06:45PM
My big DRSSTC (5-8kVA) uses a cardboard form. I spark tested it a little first to make sure it wasnt *too* conductive. It was just some sono-tube (concrete forming tube) with the outer labeling peeled off (since it was black). I coated the form and sanded it smooth, wound it, then coating it about another 10 times. Havent had any problems with the form breaking down, even when getting near 3X the winding length in sparks. It flashed across the entire coil at one point (rather than through the cardboard), which i think is a testement to its performance as an insulator. Of course, not all cardboard is created equally.. as they say, your mileage may vary. Id suggest spark testing a bit of it to see if its particularly conductive.
Steve Ward, Sun Mar 04 2007, 06:45PM
My big DRSSTC (5-8kVA) uses a cardboard form. I spark tested it a little first to make sure it wasnt *too* conductive. It was just some sono-tube (concrete forming tube) with the outer labeling peeled off (since it was black). I coated the form and sanded it smooth, wound it, then coating it about another 10 times. Havent had any problems with the form breaking down, even when getting near 3X the winding length in sparks. It flashed across the entire coil at one point (rather than through the cardboard), which i think is a testement to its performance as an insulator. Of course, not all cardboard is created equally.. as they say, your mileage may vary. Id suggest spark testing a bit of it to see if its particularly conductive.
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