TVI & RFI Suppression

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.

Tip for finding the source of RFI and cables carrying stray RF

Use the MFJ-805 or MFJ-854 (preferred) to find the wires and cables carrying unwanted stray RF in and out of your shack and equipment. Then use either the MFJ-701 “break apart” toroid cores or use our new and highly effective RFI cores (preferred). These cores have “snap-together” baskets which securely hold the core halves together. Combine these with our famous Line Isolators, and you have the latest weapons for the fight against RFI.

These are the "big guns" in the attack on RFI. They can help on both transmit and receive.

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The RFI Quick Fix™

The "First Step" and often the only step in many "RFI Quick Fix" solutions

The RADIO WORKS' Line Isolator™

Here are the details.
The RADIO WORKS' Web Store available from this link.

Snap-on Ferrite Cores are a Must Have in the Ham Shack.

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 Cores

Featuring #31 Ferrite Mix - the best for this purpose

Up to this point, nearly all RFI beads were made with #73 material. As you can see from the chart above, it was useful from 1 through about 25 MHz. To cover the frequencies up to 300 MHz you would have to switch to #43 material. Now, at the RADIO WORKS, our new RFI “core,” which replaces about 6 beads, covers the spectrum from below 1 MHz all the way up to 300 MHz. Just as important, the impedance of the new bead is higher than previous types.

We 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

Available at the RADIO WORKS'™ Web Store

.25" i.d. "snap-on" core $ 2.50 each
.5" i.d. "snap-on" core $ 5 each

Another useful Snap-on Ferrite tool - the Toroid.


MFJ -701

RFI-free Choke Kit
Package of four core sets

With an effective range of .5 MHz to 200 MHz, these two-piece, snap together toroids have a wonderful reputation at solving difficult RFI problems. Wrap power cords, coax, input/output line onto these cores and get ready for amazing results.


Available at the RADIO WORKS'™ Web Store

Snap-on toroids, pack of 4 $26.95

Caution: In mobile installations, it may not be safe to use your radio equipment when your vehicle is in motion. RFI can affect your vehicle's onboard computer. Check with the vehicle's manufacturer.

Most Important - Most Overlooked
Grounding is Critical

6" Ground Rod Strap

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.

Available at the RADIO WORKS'™ Web Store

½ BRAID Tinned-copper braid, per foot $ 0.95
1" BRAID Tinned-copper braid, per foot $ 1.69
6" copper rod strap to attach ground braid to ground rod $ 1.49

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You'll need a jumper cable to connect Line Isolators to your equipment. We stock 18" RG-8X jumpers especially for this purpose.

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