Question about CT for SSTC
ZakWolf, Sat Oct 24 2015, 09:22PMIm building Steves mini
and I want to switch from atenna to CT feed back. I have been reading up on it but I just want to clarify.
CT gets the ground of the seconday ran through the center ?
CT amount of turns, I have seen a lot of 1:1000. Can I rewind a bobin on an E core and have the seconday gnd go through one of the spaces in the core? I dont see winding 1000 turns on a toroid.
I read that If there is high enough coupling between the pri and sec. it may be possible to use the primary grn lead for the CT . In this case the secondarys magnetic feild is absorbed by the primary and the CT will pick this up? Thats what I read but it doesnt sound right.
Since the SSTC primary ends up matching the sec. freq. via antenna feed back I dont think using the primary for the CT with this method will work.
Worse comes to worse I will just use the antenna method that the circuit calls for.
Re: Question about CT for SSTC
GrantX, Sun Oct 25 2015, 05:18AM
The 1:1000 CT's are most likely for DRSSTC circuits. They are placed over the primary coil where the peak current can easily exceed 1,000A. The primary circuit is tuned to match the secondary.
For a regular SSTC it will need to be placed over the secondary ground lead. You won't need anything close to 1,000 turns, 30 - 100 seems to be the common range. I'm about to wind a CT for my coil, I'm just using a wire from a cat5 cable and a relatively large ferrite toroid.
An E core and bobbin isn't recommended, but it might work. You would need to thread the ground lead through both holes, otherwise you will only have 0.5 turns.
GrantX, Sun Oct 25 2015, 05:18AM
The 1:1000 CT's are most likely for DRSSTC circuits. They are placed over the primary coil where the peak current can easily exceed 1,000A. The primary circuit is tuned to match the secondary.
For a regular SSTC it will need to be placed over the secondary ground lead. You won't need anything close to 1,000 turns, 30 - 100 seems to be the common range. I'm about to wind a CT for my coil, I'm just using a wire from a cat5 cable and a relatively large ferrite toroid.
An E core and bobbin isn't recommended, but it might work. You would need to thread the ground lead through both holes, otherwise you will only have 0.5 turns.
Re: Question about CT for SSTC
ZakWolf, Sun Oct 25 2015, 07:29PM
Awesome thanks!! As far as grounding what do i need to ground the coil too? Does what I ground it to effect the CT core ?
ZakWolf, Sun Oct 25 2015, 07:29PM
GrantX wrote ...
The 1:1000 CT's are most likely for DRSSTC circuits. They are placed over the primary coil where the peak current can easily exceed 1,000A. The primary circuit is tuned to match the secondary.
For a regular SSTC it will need to be placed over the secondary ground lead. You won't need anything close to 1,000 turns, 30 - 100 seems to be the common range. I'm about to wind a CT for my coil, I'm just using a wire from a cat5 cable and a relatively large ferrite toroid.
An E core and bobbin isn't recommended, but it might work. You would need to thread the ground lead through both holes, otherwise you will only have 0.5 turns.
The 1:1000 CT's are most likely for DRSSTC circuits. They are placed over the primary coil where the peak current can easily exceed 1,000A. The primary circuit is tuned to match the secondary.
For a regular SSTC it will need to be placed over the secondary ground lead. You won't need anything close to 1,000 turns, 30 - 100 seems to be the common range. I'm about to wind a CT for my coil, I'm just using a wire from a cat5 cable and a relatively large ferrite toroid.
An E core and bobbin isn't recommended, but it might work. You would need to thread the ground lead through both holes, otherwise you will only have 0.5 turns.
Awesome thanks!! As far as grounding what do i need to ground the coil too? Does what I ground it to effect the CT core ?
Re: Question about CT for SSTC
Graham Armitage, Sun Oct 25 2015, 10:38PM
I built this same SSTC and also switched from antenna to CT. Wound about 30 turns of cat-5 single strand wire on the torroid with the base of the secondary running through it to the ground. For the ground I connected everything to the mains ground. Here is my setup
Graham Armitage, Sun Oct 25 2015, 10:38PM
I built this same SSTC and also switched from antenna to CT. Wound about 30 turns of cat-5 single strand wire on the torroid with the base of the secondary running through it to the ground. For the ground I connected everything to the mains ground. Here is my setup
Re: Question about CT for SSTC
ZakWolf, Mon Oct 26 2015, 03:26AM
Mains ground really ? I was thinking more of either an earth ground or a pseudo ground ( large metal surface). Just in Case I want to move it about and taking it places that might not have a true ground. I do not want and RF going back into the mains and disrupting or harming sensitive equipment.
Can I use a filter on the mains input ? then I can use it for a ground.
What kind of filter would I need for a coil like this, they are frequency specific right ?
Probably gonna start a project thread to show the building process of it later. Thanks !!
ZakWolf, Mon Oct 26 2015, 03:26AM
Graham Armitage wrote ...
I built this same SSTC and also switched from antenna to CT. Wound about 30 turns of cat-5 single strand wire on the torroid with the base of the secondary running through it to the ground. For the ground I connected everything to the mains ground. Here is my setup
Thats good. I have a CT with 42 turns of small solid wire. I built this same SSTC and also switched from antenna to CT. Wound about 30 turns of cat-5 single strand wire on the torroid with the base of the secondary running through it to the ground. For the ground I connected everything to the mains ground. Here is my setup
Mains ground really ? I was thinking more of either an earth ground or a pseudo ground ( large metal surface). Just in Case I want to move it about and taking it places that might not have a true ground. I do not want and RF going back into the mains and disrupting or harming sensitive equipment.
Can I use a filter on the mains input ? then I can use it for a ground.
What kind of filter would I need for a coil like this, they are frequency specific right ?
Probably gonna start a project thread to show the building process of it later. Thanks !!
Re: Question about CT for SSTC
Graham Armitage, Mon Oct 26 2015, 04:32PM
Yup - a line filter (matching the power input) is what is I use. Keeps the RF out of the house mains. I also want to be able to make it mobile and digging a hole in a school classroom for dedicated ground is not realistic. Never had any problem with RF filter and mains grounding. EM interference from the coil discharge is a much bigger problem.
I will add the connecting to mains ground and a dedicated RF ground could be problematic with ground loop issues. I try and avoid that.
Graham Armitage, Mon Oct 26 2015, 04:32PM
Yup - a line filter (matching the power input) is what is I use. Keeps the RF out of the house mains. I also want to be able to make it mobile and digging a hole in a school classroom for dedicated ground is not realistic. Never had any problem with RF filter and mains grounding. EM interference from the coil discharge is a much bigger problem.
I will add the connecting to mains ground and a dedicated RF ground could be problematic with ground loop issues. I try and avoid that.
Re: Question about CT for SSTC
ZakWolf, Tue Oct 27 2015, 12:53AM
Gotcha, you said matching the power input. Like in wattage ? I thought the the filter only blocked a narrow band of frequencies and need to be somewhat specific to the target RF.
I think this coil draws about 3-5 amps
ZakWolf, Tue Oct 27 2015, 12:53AM
Graham Armitage wrote ...
Yup - a line filter (matching the power input) is what is I use. Keeps the RF out of the house mains. I also want to be able to make it mobile and digging a hole in a school classroom for dedicated ground is not realistic. Never had any problem with RF filter and mains grounding. EM interference from the coil discharge is a much bigger problem.
I will add the connecting to mains ground and a dedicated RF ground could be problematic with ground loop issues. I try and avoid that.
Yup - a line filter (matching the power input) is what is I use. Keeps the RF out of the house mains. I also want to be able to make it mobile and digging a hole in a school classroom for dedicated ground is not realistic. Never had any problem with RF filter and mains grounding. EM interference from the coil discharge is a much bigger problem.
I will add the connecting to mains ground and a dedicated RF ground could be problematic with ground loop issues. I try and avoid that.
Gotcha, you said matching the power input. Like in wattage ? I thought the the filter only blocked a narrow band of frequencies and need to be somewhat specific to the target RF.
I think this coil draws about 3-5 amps
Re: Question about CT for SSTC
Benjamin, Tue Oct 27 2015, 03:06AM
I built a small coil using Steve's sstc5 schematic but with a 1:80 secondary base current transformer and no line filter, just using the mains ground. It worked great and I never blew anything up.
Benjamin, Tue Oct 27 2015, 03:06AM
I built a small coil using Steve's sstc5 schematic but with a 1:80 secondary base current transformer and no line filter, just using the mains ground. It worked great and I never blew anything up.
Re: Question about CT for SSTC
ZakWolf, Tue Oct 27 2015, 04:22AM
Interesting I have heard lots of mixed things about SSTC. I have had working versions of this coil before and it seems to be a very forgiving and predicable coil. I think ill just run it with the mains ground and earth ground when I can.
ZakWolf, Tue Oct 27 2015, 04:22AM
Benjamin wrote ...
I built a small coil using Steve's sstc5 schematic but with a 1:80 secondary base current transformer and no line filter, just using the mains ground. It worked great and I never blew anything up.
I built a small coil using Steve's sstc5 schematic but with a 1:80 secondary base current transformer and no line filter, just using the mains ground. It worked great and I never blew anything up.
Interesting I have heard lots of mixed things about SSTC. I have had working versions of this coil before and it seems to be a very forgiving and predicable coil. I think ill just run it with the mains ground and earth ground when I can.
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