RF Toroid Calculator by VK3CPU
Snap On RF Choke/Isolator - 3/4"/18.7mm cable, 5/10/15 Bead Option, 1-300 MHzProduct DetailsBrand: Palomar EngineersMPN: SNO-3/4-5Effective Frequency Range (MHz): 3-100PEP Power Rating (watts): same as coax cable ratingEstimated Insertion Loss (db): .025Input Connector Type: noneOutput Connector Connector Type: noneGround Connector (Y/N): noneEnclosure Size (LxWxH inches): noneUse for 3/4″ Cable LDF-4, Heliax(R), LMR-600, etc.
Use five split beads for 80-10 meters (3-30 MHz) or ten split beads for 160-10 (1.8-30 MHz) meters or use 15 split beads for even higher choking for 1-10 MHz.
Typical Impedance per split bead: 10 MHz: 50 ohms, 25 MHz: 95 ohms, 100 MHz: 195 ohms, 250 MHz: 322 ohms
A minimum impedance of 500 ohms is needed for 50 ohm cable or 10 times the cable impedance for other cables.
The beads clamp to the cable and may be operated as is for indoor or outdoor use. For longer life outdoors to protect the plastic covers from weathering – use electrical tape for best results or heat shrink to ensure longer life. All kits come with instruction manual which covers assembly and application tips.
As you can see from the impedance vs frequency graph, you can very effectively increase the choking impedance by increasing the number of beads on the cable.
Excellent choke size for multi-turn RG-8X or similar size cables
Snap On and Slip on Feed line chokes available in sizes to fix cables with outside diameters of 1/4", 3/8", 1/2", 3/4", 1" - check website for other size options.
Tutorials
Use for 3/4″ Cable LDF-4, Heliax(R), LMR-600, etc.
Use five split beads for 80-10 meters (3-30 MHz) or ten split beads for 160-10 (1.8-30 MHz) meters or use 15 split beads for even higher choking for 1-10 MHz.
Typical Impedance per split bead: 10 MHz: 50 ohms, 25 MHz: 95 ohms, 100 MHz: 195 ohms, 250 MHz: 322 ohms
A minimum impedance of 500 ohms is needed for 50 ohm cable or 10 times the cable impedance for other cables.
The beads clamp to the cable and may be operated as is for indoor or outdoor use. For longer life outdoors to protect the plastic covers from weathering – use electrical tape for best results or heat shrink to ensure longer life. All kits come with instruction manual which covers assembly and application tips.
Excellent choke size for multi-turn RG-8X or similar size cables
Snap On and Slip on Feed line chokes available in sizes to fix cables with outside diameters of 1/4", 3/8", 1/2", 3/4", 1" - check website for other size options.