How The ELMER Brand Kills CMC

To understand how our chokes "kill" unwanted RF, you have to understand Reactive Impedance. A common mode choke is essentially a frequency-dependent "stop sign" for the outside of your coax.

1. High-Impedance Blocking (The Ferrite Core)

Common Mode Current (CMC) travels on the skin of your coax shield. By wrapping that shield in our Fair-Rite Type 31 and 43 Ferrite cores, we create a high-impedance "choke point."

• The Physics: When RF tries to pass through the magnetic field created by our ferrites, it encounters massive resistance (measured in Ohms).

• The Result: The ferrites effectively "decouple" the antenna from the feedline. The "good" signal stays inside the coax (Differential Mode) completely untouched, while the "bad" RF on the outside is converted into a tiny, harmless amount of heat.

2. Why Mix 31 and Mix 43 Matter

Most off-the-shelf chokes use generic ferrites. The ELMER Brand uses specific formulations based on your operating frequency:

• Fair-Rite Type 31: This is the "Gold Standard" for HF (1–30 MHz). It provides the highest impedance across the widest range, ensuring that even on the lower bands (80m/160m) where CMC is most aggressive, your station stays quiet.

• Fair-Rite Type 43: Optimized for the higher end of HF into VHF/UHF. If you are a 6m, 2m, or 70cm operator, Type 43 provides the surgical precision needed to stop "RF in the shack" without affecting your SWR.

3. Maintaining Velocity Factor with Messi & Paoloni

Stopping the "bad" RF is only half the battle. You also have to protect the "good" signal. Standard coax can be "lossy," meaning you lose power before it even hits your antenna.

• M&P POTA 7 & Airborne 5: These cables feature a proprietary triple-layer shield and a high-percentage braid.

• The ELMER Edge: Because the internal shielding of our M&P coax is so superior, it naturally resists "leakage" better than standard RG-58 or RG-8X. When combined with our ferrites, you get a dual-layer defense: superior internal shielding plus massive external suppression.

4. Precision Saturation (The 5 vs. 7 Ferrite Strategy)

In RF engineering, "more" isn't always better—correct is better. We’ve tested our chokes to find the "Sweet Spot" of saturation.

• Using 7 Ferrites in our POTA models provides the necessary inductive reactance to handle higher power levels and longer feedlines without the ferrites "saturating" (becoming ineffective).

• This ensures that even under heavy digital modes (FT8) or high-duty cycle CW, your choke remains a brick wall against Common Mode Current.