Uploaded July 2020 | Updated September 2026, 2 weeks ago
Checking toroids purchased at a Hamfest with a Gid Dip meter or solid state dip meter . I wanted a method of testing toroid cores to determine if they were good for RF use in a QRP transmitter . So playing with the Heathkit tunnel dipper I found an easy method to determine if a toroid core was a Common Mode noise filter core that you put on a computer cable or a power cable in a rig to cut down EFI noise or is it a toroid suitable for RF .
I have gotten some BIG toroids and wanted to make a balun for HF only to find it did not work WHY ? you say . Well because it was not an RF toroid core
it was a Noise filter core called a common mode noise filter core these are not suitable for RF . So shown in the video is a simple way I figured out to check toroid cores to see if they are ok for RF use . I then tried using the Kenwood DM-81 dip meter and found it worked much better than the Heathkit tunnel dipper the tunnel dipper gave a small hard to find dip using this method . I imagine that the heathkit tube type dipper would work well as would a Millen grid dipper . 73 Bob
Checking toroids purchased at a Hamfest with a Gid Dip meter or solid state dip meter . I wanted a method of testing toroid cores to determine if they were good for RF use in a QRP transmitter . So playing with the Heathkit tunnel dipper I found an easy method to determine if a toroid core was a Common Mode noise filter core that you put on a computer cable or a power cable in a rig to cut down EFI noise or is it a toroid suitable for RF .
I have gotten some BIG toroids and wanted to make a balun for HF only to find it did not work WHY ? you say . Well because it was not an RF toroid core
it was a Noise filter core called a common mode noise filter core these are not suitable for RF . So shown in the video is a simple way I figured out to check toroid cores to see if they are ok for RF use . I then tried using the Kenwood DM-81 dip meter and found it worked much better than the Heathkit tunnel dipper the tunnel dipper gave a small hard to find dip using this method . I imagine that the heathkit tube type dipper would work well as would a Millen grid dipper . 73 Bob
