1/2" Snap-on cores are now available. These provide a better fit on all RG-213 size cables than do the .41" i.d. cores. The .41" i.d. cores do fit RG-213 size cables, but they are a tight fit. I have decided that it isn't worth the one dollar difference in price to take a chance on hurting the cable. The 1/2" i.d. cores are a loose fit and cannot harm cable in any way. Use the 1/2" cores for RG-213, 9913, 9096, and similar cables with the outside jacket diameter of RG-213. These are also very useful for smaller cables where you can wrap two or more turns through the core. Each turn has the effect of adding an additional core. |
Line
Isolators The first line of RFI Quick Fix defense. |
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Use a RF current meter such as the MFJ MFJ-805 or MFJ-854 (preferred) to find the wires and cables carrying unwanted stray RF in and out of your shack and equipment. These meters have probes which open and close around a wire or cable, so they are fast and easy to use. When you find a wire or cable that produces a reading on the RF current meter, then it would be appropriate to use "snap-on" Ferrite cores on that wire or cable. You may need to use more than one. After applying the snap-on Ferrite core(s), measure the RF current and note the improvement. Combine these with our famous Line Isolators, and you have the latest weapons for the fight against RFI. |
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These are the "big guns" in the attack on RFI. They can help on both transmit and receive. ![]() ![]() |
The RFI Quick FixThe "First Step" and often the only
step in many "RFI Quick Fix" solutions
The RADIO WORKS' Line Isolator
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Snap-on Ferrite Cores are a Must Have in the Ham Shack. |
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![]() ![]() ![]() Four snap-on cores are shown on each cable. In some cases, more may be needed. Each core provides around 150 ohms of inductive reactance at most HF frequencies. |
Snap-on Ferrite CoresFeaturing #31 Ferrite Mix - the best for this purposeWe stock Ferrite Cores in the two most popular sizes with inside diameters with .25 or .5". Both cores use the new #31 ferrite material. If you use some other ferrite mix, you won't get the best results. Also, you have to use a lot of Ferrite beads to equal these snap-on cores which are about 1.25" long. .25 Ferrite Snap-on Core - fits RG-8X, RG-59, and any 1/4 cables including smaller power and rotator cables. .5 Ferrite Snap-on Core - provide a safe, loose fit on RG-213 size coax. This includes 9096 SuperFlex, RG-213, RG-8, 9913, etc. Use for any wire or cable up to .5" or for multiple turns of smaller wires
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Most Overlooked Grounding is Critical |
Grounding is the critical step in RFI and RF feedback elimination. Without proper grounding, solutions are difficult. It's important to know the difference between RF and electrical or d.c. grounding. For important details be sure to read the information in Jim's Notebook. Grounding is the critical step in RFI and RF feedback elimination. Without proper grounding, solutions are difficult. It's important to know the difference between RF and electrical or d.c. grounding. For important details be sure to read the information in Jim's Notebook.
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