Greyline RF Choke, 500 Watt PEP, Mini Line Isolator, -35dB Common Mode Rejection 1-61 MHz
Greyline RF Choke, 500 Watt PEP, Mini Line Isolator, -35dB Common Mode Rejection 1-61 MHz

Greyline RF Choke, 500 Watt PEP, Mini Line Isolator, -35dB Common Mode Rejection 1-61 MHz

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500W Rated to be installed at the Antenna System and/or after the Amplifier in the radio station.
Country/Region of Manufacture: United States
Effective Frequency Range (MHz): 1-60
PEP Power Rating (watts): 500
Choking Impedance Range (ohms): 500-5000 (1-60 Mhz)
Common Mode Attenuation (db): 20-35db
Estimated Insertion Loss (db): .25 db
Input Connector Type: SO-239 female
Output Connector Connector Type: SO-239 female
Enclosure Size (LxWxH inches): 3" long, 2 in wide, 1.25" high

MINI CHOKE Features:

- Uses proprietary Multi-Mix, Multi-Core, Multi-Turn ferrite technology for maximum choking (up to -35 dB common-mode noise rejection) and maximum bandwidth

- 500 Watts PEP,  50-ohm SO-239 connectors In/Out, 1-61 MHz

- Works for all coax fed antennas from 1.8-61 MHz (160-6 meters) - excellent for multi-band beams, verticals, dipoles, magnetic loops, and highly unbalanced off-center fed antennas.

- 2-5 times more common-mode noise rejection, wider bandwidth, and higher power than competing isolators

MINI-CHOKER feed line chokes are used to suppress common mode current carried on the outside of the coax braid which is often responsible for receiver noise and RFI in the receiver/transmitter. These chokes are very useful for suppressing RFI common mode current at the antenna feed point, at 1/2 wavelength intervals along the coax feed line, and also at the entrance to the radio station.

This choke is available with a SO-239 input/output and ground/static bleeder stud (optional) for attachment to a ground rod. Use an isolator every 1/2 wavelength for the antenna operating frequency (include velocity factor in the calculation). Use the ground lug option for long coax antenna feed lines (over 1/2 wavelength at the operating frequency of any antenna system in the near field of the coax).

For Higher Power needs use our MAXI CHOKE 3KW version.


The RF Choke is a must-have with any antenna system and a must for Greyline Performance antenna systems too. 

By default, the Greyline Feed line Kit has slip-on or snap-on beaded Choking rated up to 3500W. Check to see if the antenna package you are choosing has the feedline kit included.

That said, some operators want more choking and assurance they are squeezing every dB of signal out of the antenna system into the radio receiver and out to the antenna for overall efficiency.

In summary, RF choking may be required at the antenna side of your feed line to keep common mode current off the coax, and at the radio side of your feed line to reduce noise (QRN) that may be picked up along the coax run back to the radio station. Every dB counts, right?

The mini 500W choke and maxi 3500W RF chokers can be added to your order for world-class common mode current choking. These are also known as line isolators and 1:1 current baluns.

Many add extra choking at the radio side to remove CMC at the radio end of the coax and also to help reduce any QRN picked up along the coaxial path to your shack. Let's get every dB we can and use it for good. 

Ham radio is fun again!


Customer Reviews

Based on 3 reviews
Gary Kalata / KC4ES
A Worthy Investment

I purchased two chokes, the coax to ladder line choke from the tuner output to the antenna ladder line and the coax to coax choke that I have installed at the radio. These work very nicely to tame noise. It's a worthwhile investment. The mini choke works better than the MFJ one that I originally was using.

Dennis Ward
Performs as expected

A good station accessory to have. The CM choke performs as expected.

William Whittaker

Worked. less noise is always better.